Examination Number: 7879463
Age-Related Changes in False Recognition
An ERP Study
Master of Science in Psychological Research Methods
The University of Edinburgh
2010 – 2011
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Examination Number: 7879463
Disclosure
“I have read and understood The University of Edinburgh guidelines on Plagiarism and declare that
this written dissertation is all my own work except where I indicate otherwise by proper use of
quotes and references.”
Acknowledgements
I would like to thank the PPLS EEG Pilot Scheme and the MSc Psychological Research Methods course
whom both funded this study and without which this research would not be possible. I would also
like to thank my family and my supervisor who both gave me excellent guidance at every stage of my
thesis.
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Examination Number: 7879463
Abstract
Episodic memory function is well known to decline with age and there is evidence to suggest seniors
prone to forget events compared to younger adults (Aizpurua & Koutstaal, 2010). What’s more,
seniors are inclined to falsely ‘remember’ events which did not happen. For example, seniors are
more affected by misleading post-event information (e.g. lures), remembering that information as
having occurred alongside the original event (Roediger & Geraci, 2007; Chan & McDermott, 2007;
Koutstaal, 2006; Aizpurua & Koutstaal, 2010).
This thesis compares two hypotheses of false memory, the Cognitive Control Hypothesis and the
Memory Specificity Hypothesis using an event-related potential (ERP) index of true recollection, an
early left parietal old/new effect (~400 to 800ms) and adapting a paradigm used by Koutstaal (2006)
which successfully demonstrated high false recognition in participants using picture stimuli.
Participants undertook two explicit forced choice tasks: unintentionally studying picture stimuli by
answering a size-judgment task and later a recognition test where they could answer either “old”
(for repeated stimuli), “similar” (lures) or “new” (novel).
Results supports previous behavioural findings by demonstrating seniors are significantly worse at
discriminating between repeated and novel stimuli than younger adults, despite similar end
performances with respect to repeated and novel stimuli. In addition, evidence shown here supports
the suggestion that seniors are inclined to falsely “remember” events which did not happen, by
misleading post-event information, compared to younger adults. An exploratory analysis of left
parietal old/new effects from collected ERP data revealed unexpected conclusions. False alarms to
lure stimuli (by answering “old”) showed significantly greater magnitudes compared to all other
critical conditions in both age groups. This is not supported by previous research. However, younger
participants showed greater correct responses to old items with greater magnitudes than correctly
rejected new items which is supported by previous research.
While neither hypothesis could be accepted based on the information gathered, the study design
worked well and could easily be repeated. Future research replicating this study and combining it
with other behavioural, ERP and fMRI results with undoubtedly yield a better understanding of the
underlying processes involved cognitive ageing.
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Contents
Introduction
Page 1 – 13
Memory in Normal Ageing
Page 1 – 4
Brain Regions of Interest
Page 4 – 7
Cognitive Control Hypothesis
Page 7
Memory Specificity Hypothesis
Page 7 – 8
Expected ERP Indices
Page 8 – 10
Thesis Aims, Questions and Expectations
Page 10 – 12
Method
Page 13 – 18
Participants
Page 13 -14
Neuropsychological Tests
Page 14
Design
Page 14
Materials
Page 14 – 15
Procedure
Page 15 – 18
ERP Recording and Pre-processing
Page 18
Results
Page 19 – 28
Neuropsychological Test Performance
Page 19
Behavioural Analysis Strategy
Page 20
Behavioural Task Performance
Page 20
Accuracy analysis
Page 20
Response times analysis
Page 22
Discrimination and response bias analysis
Page 23
ERP Analysis Strategy
Page 24 -25
ERP Data
Page 25 – 28
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Discussion
Page 29
Neuropsychological Test Findings
Page 29
Behavioural Findings
Page 30
ERP Findings
Page 31
General Discussion
Page 32
Conclusion
Page 36
References
Page 37 – 50
Appendix A (Consent forms)
Page 51 – 54
Appendix B (EEG procedure)
Page 55
Appendix C (Information sheets for experiment tasks)
Page 56 - 59
Appendix D (Hand-charts for EEG experiment)
Page 60-63
Appendix E (Pilot results)
Page 64 - 68
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Examination Number: 7879463
Introduction
Episodic memory is an essential part of cognition and necessary for many abilities including decision
making, categorisation, speech and planning. Improved episodic performance enhances these
abilities and offers an evolutionary advantage as the ability to learn and remember allows the
consequence of actions to be predicted from previous experience, with better adaptation to
changing situations (Aizpurua & Koutstaal, 2010; Shing et al., 2010; Gronlund, Carlson & Tower,
2007; Dickerson & Eichenbaum, 2009). However, episodic memory function is well known to decline
with age (Aizpurua & Koutstaal, 2010). Compared to other skills, failings in memory are the
commonest complaints of seniors (Newson & Kemps, 2006; Yassa et al., 2010; Chan & McDermott,
2007). While there is evidence demonstrating seniors are prone to forget specific events. There is
also evidence that seniors are inclined to falsely ‘remember’ events which did not happen. For
instance, seniors are more affected by misleading post-event information, remembering that
information as having occurred alongside the original event (Roediger & Geraci, 2007; Chan &
McDermott, 2007; Koutstaal, 2006; Aizpurua & Koutstaal, 2010).
This thesis will investigate the impact of normal ageing on memory retrieval using a recognition
paradigm under electroencephalogram (EEG) conditions developed from Koutstaal’s (2006) study
which demonstrated enhanced false memory in seniors. This thesis will explore the background to
recognition memory, the theory behind the Cognitive Control and Memory Specificity Hypotheses
and the event-related potential (ERP) indicator I will be used to compare the two hypotheses.
Memory in Normal Ageing
In memory research, an important concept is ‘Multiple Memory Systems’. This theory assumes that
memory is not one single entity but divided into separate categories and sub-categories which
seemingly similar, differ in the type of information they process (Sherry & Schacter, 1987;
Moscovitch & Winocur, 1995; Squire, 2004). This study focuses on episodic memory, “[A system]
recently evolved, late-developing and early-deteriorating past-orientated” giving an individual
“[conscious awareness] of an earlier experience in a certain situation at a certain time”, allowing
mental time-travel to previous events to re-live experiences (Tulving, 1972; 1993; 2002 p.5). This
unique aspect of ‘mental time-travel’ separates it from other memory systems (Wheeler, Struss &
Tulving, 1997). Research shows that episodic, prospective and working memory noticeably decline
with increased age compared to other putative memory systems such as semantic memory, an
individual’s memory for facts and knowledge (Duverne, Habibi & Rugg, 2008; Grady & Craik, 2000).
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For example remembering that the capital of Scotland is Edinburgh, is preserved through life if it is
frequently used while memory for specific information, for example remembering the situation
surrounding being taught that fact, declines more rapidly (Luo & Craik, 2008).
Episodic memory can be split into four broad theoretical areas: an initial transformation of sensory
information into a representation (event) required for storage (i.e. encoding); the strengthening of
that event over a period of time (i.e. consolidation); the storage of the event and the recall of that
event (i.e. retrieval) (Tulving, 1972; Mayes & Roberts, 2001). The aspect of retrieval and recognition
memory, the ability to decide if a presented item has been previously experienced and the impact of
normal ageing upon them is the focus for this thesis. Seniors are less able to correctly classify
incoming information as either known or novel and are prone to forget specific events (Roediger &
Geraci, 2007). In addition there is also evidence that seniors are prone to ‘remember’ events which
did not happen. For instance, misleading post-event information will affect seniors more than
younger adults, with seniors attributing this post-event information as having occurred alongside the
original event (Aizpurua, Garcia-Bajos & Migueles, 2009; Mitchell, Johnson & Mather, 2003;
Multhaup, De Leonardis & Johnson, 1999; Chan & McDermott, 2007).
This increase in false memory in seniors was demonstrated in paradigms such as the false-fame
paradigm (Multhaup, 1995; Davidson & Glisky, 2002). In this instance participants would study lists
consisting of names of people participants were told were non-famous. At test, participants were
asked to identify the famous names in a new list. This list would contain famous names, non-famous
names and names from the previous list. Seniors demonstrated increased false-fame errors
compared to younger adults (Multhaup, 1995). Seniors’ susceptibility to false recognition has been
shown in drawings (Koutstaal, 2006), complex scenes (Gutchess et al., 2005), word-pair tasks (Grady
& Craik, 2000; Castel & Craik, 2003; Hay & Jacoby, 1999), sentences (Bayen, 1999) and in one of the
most widely used paradigms, the Deese/Roediger-McDermott (DRM) task (Roediger & McDermott,
1995). The DRM task includes word lists (e.g. boat, whale, blue, waves) where a majority of the
words are linked by a semantically related “lure” word (in this case ‘ocean’). Participants learn the
lists presented (study phase) and are later asked to recall the word lists (test phase). Seniors will
falsely remember the non-presented lure word more frequently than younger adults with a high
confidence that it appeared in the original list (Norman & Schacter, 1997; Wiese & Daum, 2006; Luo
& Craik, 2008; Chan & McDermott, 2007).
In order to assess why seniors’ were more susceptible to lure items Koutstaal & Schacter (1997) used
a picture recognition paradigm. Here, participants studied multiple different pictures from various
categories (e.g. boats, shoes, cats) along with unrelated pictures not belonging to any category (e.g.
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a snow sled, a hand bell). At test, participants made “old” versus “new” judgments on whether
pictures were shown before or novel from a list of previously studied items, related lure pictures and
unrelated pictures. Seniors showed more false recognition to the lure pictures than younger adults.
Seniors also showed similar correct “old” responses to young for pictures from large categories and
impaired correct “new” responses for unrelated lure pictures. This type of performance suggests
that within recognition memory seniors have a preserved access to information about general
similarities but impaired access to distinctive information (Koutstaal & Schacter, 1997; Schacter et
al., 1998).
Research into recognition memory tends to take a dual-process account where recognition memory
performance is determined by two separate processes: recollection, which is context-dependent so
that specific details about a previous encounter are retrieved and familiarity occurring when the
encounter is recognised but without context (e.g. you meet a person and recognise their face but
cannot remember the name or when/where you saw that person) (Mecklinger & Jäger, 2009;
Eichenbaum, Yonelinas & Ranganath, 2007; Shing et al., 2010). Both familiarity and recollection are
thought to aid the correct judgement on whether a newly presented item/event is truly novel or not
(Wiese & Daum, 2006; Davidson & Glisky, 2002; Cheng & Rugg, 2004; Shing et al., 2010). While the
exact mechanisms underlying seniors’ performance in recognition tests such as the DRM are still to
be explained, differences can be explained by two general theories. The first is an impaired ability in
a mechanism during encoding that binds together different aspects of memory into a coherent
representation and at retrieval separates aspects of memory into a distinct event (i.e. an
“associative” deficit). Here, seniors would show less detailed recollection in a recognition task. The
second possible impairment is a “strategic/monitoring” deficit causing seniors to over generalize in
their search criteria at encoding and fail to correctly verify/evaluate the relevant information at
retrieval (Shing et al., 2010; Davidson & Glisky, 2002; Schacter et al., 1998). In this case seniors
would fully recollect information but the information would be less specific (due to impaired
strategic encoding) or would be incorrectly utilized (due to impaired strategic retrieval).
Gallo, Bell, Beier & Schacter (2006) propose that seniors deficits in strategic recollection are due to
two types of monitoring processes. There is evidence that both are used for the successful rejection
of lure items and that both processes are diminished in seniors (Chan & McDermott, 2007; Gallo et
al., 2006; Gallo, 2004). The first is a diagnostic monitoring process, the distinctiveness heuristic and
the second is a disqualifying process called recall-to-reject. Recall-to-reject can be defined as an
editing process which aids in avoiding “lure” material by recalling the lures’ instantiating study item
(i.e. “I didn’t see this item because I remember a similar one previously shown”) while the
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distinctiveness heuristic is defined as aiding avoiding lures because of a failure to recall expected
information (i.e. “I didn’t see this item because I’d remember if I had”) (Odegard & Lampinen, 2005;
Gallo et al., 2006; Dodson & Schacter, 2002). Associative deficits can be accounted for by a failure of
pattern separation, defined as a mechanism for separating partially overlapping patterns of
activation to successfully retrieve one specific episodic event separate from other patterns/events
(Gilbert, Kesner & Lee, 2001; Toner, Pirogovsky, Kirwan & Gilbert, 2009). When this pattern
separation fails, high levels of overlap occur between items creating a sustained or increased
memory for what items have in common (i.e. gist) but impairing the successful recall of specific,
distinctive items. Consequently participants will be more likely to falsely recollect items (Schacter et
al., 1998).
Brain Regions of Interest
Functional magnetic resonance imaging (fMRI) studies present growing evidence that both the
frontal lobes (FLs) and the medial temporal lobes (MTLs) contribute to age-related changes in
recognition memory (Davidson & Glisky, 2002; Moscovitch & Winocur, 1995). Research on brain
regions involved with memory began with patient H.M. who suffered severe epileptic fits and
underwent surgery to remove his hippocampus and alleviate seizures. Although seizure activity
decreased, the surgery left him unable to commit new information to memory. His symptoms
included difficulties in recognising faces and a severe functional impairment as he could no longer
remember when or what his last meal was, his age or even his carers (Corkin, 2002). These drastic
changes following surgery for patient H.M. and other amnesic patients such as Clive Wearing and
Jon focused research on the hippocampus and parahippocampal area (i.e. the medial temporal
lobes, MTLs) (Squire, Wixted & Clark, 2007; Baddeley, 2001; Moscovitch & Winocur, 1995). Evidence
of the significance of the MTLs with respect to episodic memory has accumulated, however, the
importance of the MTL with respect to normal age-related deficits in recognition is still debated.
Research from post-mortem examinations and in vivo structural neuroimaging (e.g. MRI and
positron emission tomography; PET) suggests age-related morphological changes (i.e. anatomical
and physiological degradation such as cortical thinning and gyral atrophy) are prominent in the
prefrontal cortex (PFC) (Blatter et al., 1995; Raz et al., 1997; 2005; Sowell et al., 2003; Persson et al.,
2006). There is also evidence of age-related morphological changes in the MTL (particularly the
hippocampus), however, this is not consistent. The PFC consistently undergoes the steepest decline
(Dennis & Cabeza, 2008, p.3). Current evidence suggests that these morphological changes,
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particularly in the PFC, compel our brains to reorganise their functions (Persson et al., 2006).
Seniors’ decreased performance in DRM and other recognition tasks suggests that FL age-related
changes are linked with failing memory in the elderly (Moscovitch & Winocur, 1995).
Evidence suggests that with standard neuropsychological testing of frontal lobe function seniors
consistently perform worse than younger adults (Koutstaal, 2006; West, 1996). ). In addition, in
situations where seniors do not consistently perform less well in FL tests, those that show low
frontal lobe performance have increased levels of false recognition (Butler, McDaniel, Dornburg,
Prince & Roedigger, 2004). Although PFC damage has not been shown to directly incur severe
amnesic symptoms, deficiencies occur within executive functioning (i.e. a set of cognitive abilities
that control and regulate other abilities and behaviours) (West, 1996; 2000, West & Schwarb, 2006).
This is thought to impact upon retrieval strategies and may account for differences between younger
populations and seniors during recognition tasks (Naveh-Benjamin, Brac & Oded, 2007; Chan &
McDermott, 2007; West & Schwarb, 2006; Wiese & Daum, 2006). Other studies have found links
between FL function and susceptibility to use general memory, “gist” (Koutstaal, 2006; Aizpurua et
al., 2009). Multhaup (1995) demonstrated in the false-fame paradigm that by encouraging seniors’
participants to use more stringent decision criteria, where participants categorized names (whether
famous vs. non-famous) in terms of their source, seniors’ false recognition performance matched
younger adults performance. Strategic manipulations in Multhaup’s (1995) study and others
demonstrate that improving FL/executive function can decrease false recognition (Davidson &
Glisky, 2002).
However, there is also evidence pointing away from FL deficits. For example, Chan & McDermott
(2007) tested recollection using a DRM paradigm. In this case neuropsychological tests indicating
frontal lobe functioning and age-related factors were shown to be independent contributors to
recollection performance. They concluded that another factor, separate from frontal lobe function,
must contribute to seniors’ heightened susceptibility to false memories. Aizpurua & Koutstaal’s
(2010), also using standard neuropsychological tests of FL function, demonstrated that seniors’ FL
function was not significantly correlated with successful recollection. Furthermore, other studies
have shown that despite encouragement to make stringent decision strategies in both recall-toreject and distinctiveness heuristic monitoring processes this does not fully reduce false recognition
levels in seniors to that of younger adults (Koustaal & Cavendish, 2006; Koustaal, Schacter, Galluccio
& Stofer; 1999; Gallo et al., 2006).
Associative deficits, specifically pattern separation, linked to MTL structures may be contributing to
seniors’ decreased performance in recognition tasks. PET and fMRI studies have demonstrated that
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successful recollection of materials is correlated with increased hippocampus activity in the blood
oxygen level-dependent (BOLD) signal as well as cerebral blood flow (CBF) (Suzuki, Johnson & Rugg,
2011a; 2011b; Rugg, Fletcher, Frith, Frackowiak & Dolan, 1997; Cabeza & Nyberg, 1997; 2000; Kapur,
Friston, Frith & Frackowiak, 1995). Furthermore, there is evidence suggesting the dentate gyrus (DG)
sub-region in the hippocampus and its CA1/3 mossy fibre projections supports pattern separation
(Gilbert et al., 2001; Kesner, 2007; Myers & Scharfman, 2009; Rolls, 1996; Bakker, Kirwan, Miller &
Stark, 2008). In senior adults decreased performance in recognition can be linked to decreases in the
hippocampus and specifically the dentate gyrus. (Toner et al., 2009; Wilson, Ikonen, Gallagher,
Eichenbaum & Tanila, 2005). When pattern separation fails, high levels of overlap occur between
items creating a sustained or increased memory for what items have in common (i.e. gist) but
impairs the successful recall of specific, distinctive items. Consequently participants will be more
likely to falsely recollect items (Schacter et al., 1998). Popular theories of consolidation such as the
‘Standard Model’ (Squire & Zola-Morgan, 1991) and the ‘Multiple Trace Theory’ (Nadel &
Moscovitch, 1997) can account for the pattern separation hypothesis. They suggest that the
fundamental features of each memory representation are consolidated in the hippocampus which
initially binds different aspects of memory, throughout the brain; such that no single location
contains a complete record of the specific episodic event (Squire, 1992; 1995; Dudai, 2004; Nadel &
Moscovitch, 1997). When part of an event is retrieved, a process of spreading activation occurs
through the subset of that event’s features until the rest of the constituent features are recalled
(Schacter et al., 1998; Dudai, 2004). Within the pattern separation hypothesis, if a recognition test
item has been incorrectly ‘connected’ to other memory aspects or when retrieved spreading
activation has not fully occurred, then correct pattern separation will be unsuccessful.
In summary, there is evidence for both MTL and FL involvement in recognition memory, false
memory and age-related changes in these areas. Due to its monitoring processes, the FL can be
considered to impact on the reliance of familiarity processes while the MTL can be considered to
impact both familiarity itself and recollection processes (Shing et al., 2010). This is supported by the
roles FLs and MTLs have been accorded in the literature. Medial temporal lobe function can be
described as associative with the hippocampus a core component, allowing for pattern completion
to generate successful recollection while frontal lobe function monitors the input and output from
the MTLs by using a distinctiveness heuristic and recall-to-reject in order to conclude which stimuli
presented are novel and which are known (Moscovitch & Winocur, 1995; Davidson & Glisky, 2002).
While pattern separation, recall-to-reject and the distinctiveness heuristic are not the only processes
involved in recognition memory, they are fundamental to this thesis which focuses on ageing
changes and specifically in false memory: all have been independently shown to be impaired in
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seniors when falsely recognising information in DRM and other tasks (Chan & McDermott, 2007;
Moscovitch & Winocur, 1995; Koutstaal, 2006; Toner et al., 2009; Wilson et al., 2005). In addition,
due to the relatively automatic role of the hippocampus (and general MTL) within retrieval, binding
constituent features together into a coherent memory trace, pattern separation is considered to be
relatively quick. On the other hand, the strategic role of the FL appear to be effortful; possibly selfactivated spontaneously or by instruction and consequently slower (for review see Shing et al., 2010;
Rugg & Curran, 2007).
Evidence for the hypotheses of pattern separation, recall-to-reject and the distinctiveness heuristic
can be grouped into two broad theories of decreased recognition performance in senior adults
where false recognition increases: the Cognitive Control Hypothesis (West, 1996; 2000; Gallo et al.,
2006; Koutstaal, 2006) and the Memory Specificity Hypothesis (Shing, Werkle-Bergner, Li &
Lindenberger, 2008; Luo & Craik, 2008).
Cognitive Control Hypothesis
The Cognitive Control Hypothesis (CCH) is based on research on FL function and proposes that FL
age-related decline is the main component to a decline in successful recognition. In false recognition
paradigms seniors demonstrate strategic deficits (e.g. in distinctiveness heuristic processes and
recall-to-reject processes) and consequently show an over-reliance on familiarity, performing less
well than their younger counterparts. Seniors performance on frontal lobe neuropsychological tests
should also predict their performance in false memory paradigms: with seniors who perform worse
in the neuropsychological test being more likely to be misled by lure items (Dodson & Schacter,
2002; West, 1996; West, 2000; Gallo et al., 2006).
Memory Specificity Hypothesis
The Memory Specificity Hypothesis (MSH) is based on both the MTL and FL function. It assumes that
seniors will perform lower than younger adults with both strategic deficits (due to FL age-related
changes) where recall-to-reject and distinctiveness heuristic monitoring are impaired long with a
pattern separation deficit (due to MTL changes; Toner et al., 2009; Wilson et al., 2005). For example,
while the CCH proposes seniors’ will make false recognition errors based on less specific information
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from an overwhelming feeling of familiarity or the inappropriate use of gist, the MSH instead
proposes that seniors will also experience convincing false recollections (Kroll, Knight, Metcalfe,
Wolf & Tulving, 1996; Dodson, Bawa & Slotnick, 2007). Seniors will be more likely than young adults
to fully recall false memories by combining features of different episodes (items) causing seniors to
falsely recall with high confidence. Previous research supports this concept of confident false
recollection in seniors (Dodson, Bawa & Krueger, 2007; Lyle & Johnson, 2006; Chua, Schacter &
Sperling, 2009).
Expected ERP Indices
Despite the amount of behavioural evidence, results from behavioural studies are limited in making
firm conclusions on the processes underlying recognition memory, whether they be FL-based or
MTL-based (Wolk et al., 2009). For example, previous research has shown seniors performing
similarly to younger subjects on recognition memory tasks (Yonelinas, 2002). However, alternative
cognitive and neural processes may underlie this equivalent performance. By using techniques such
as event-related potentials (ERPs), which has excellent temporal resolution, age-related differences
in behavioural tasks can be related to neural and cognitive processes (Wolk et al., 2009).
Previous studies have frequently identified three event-related potentials (ERP) which in relation to
recognition memory: an early (~300-500ms) right frontal effect and mid-frontal effect (FN400) along
with a later (~400-800ms) left parietal effect (Curran, 2004; Curran & Cleary, 2003; Wilckens, Tremel,
Wolk & Wheeler, 2011; Ally, Simons et al., 2008; Vilberg & Rugg, 2008; 2009; Rugg, Otten & Henson,
2002; for review see Mitchell & Johnson, 2009). All waveforms effects show recollected items (‘old’)
demonstrating a more positive deflection than correctly rejected novel items (‘new’), termed
old/new effects and are found in a variety of recognition tests that use both word and picture
stimuli, including word-plurality, temporal source recognition, word-modality and word-pairs
(Yonelinas, 2002; Guerin & Miller, 2009; Donaldson & Rugg, 1998; Wilding, 2000; Trott, Friedman,
Ritter, Fabiani & Snodgrass, 1999).
The FN400 old/new effect, is similar to established N400 waveforms but has different scalp
topography and the right frontal effect are both generally accepted to reflect familiarity processes in
recognition memory (Kutas & Federmeier, 2011; Mayes & Roberts, 2001; Paller, Voss & Boehm,
2007; Wilding & Rugg, 1997; Rugg et al., 2002; Hayama, Johnson & Rugg, 2008). This conclusion is
supported by the post-retrieval monitoring nature of strategic (i.e. executive) frontal lobe
dependent processes that are therefore seen after automatic recollection effects (Shing et al., 2010;
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Mitchell & Johnson, 2009; Rugg & Curran, 2007). Conversely, the left parietal “old/new” effect has
been repeatedly associated with successful recollection of materials (Wilding, 2000; Rugg & Curran,
2007; Ally, Simons et al., 2008). While parietal involvement in recollection may be at first thought
unusual, parietal regions have long been linked with the MTLs (Wilding & Rugg, 1996; 1997; Rugg,
Schloerscheidt & Mark, 1998; for review see Mitchell & Johnson, 2009; Wagner, Shannon, Kahn &
Buckner, 2005).
In Wilding & Rugg (1996; 1997) and Wilding’s (2000) study’s participants listened to words spoken
aloud either in a male or female voice. When participants were tested, presented lists of words in
which they made “old” (repeated) or “new” (novel) judgements and when answering “old” making a
source (context) judgement on the gender of the speaker, correct source judgments were linked to
left parietal old/new effects. Here, correct source judgements would elicit increased left parietal
activity in comparison to incorrect source judgements or new judgements. Since correct source
judgments are dependent on correct recollection it follows that the left parietal old/new effect can
be linked with recollection (Cheng & Rugg, 2004). Other evidence investigating depths of processing,
where the meaning of an item has been deepened (i.e. adding ‘meaning’ to an item compared to a
simply sensory analysis such as colour, shape), has been linked to left parietal old/new effects.
Items, which have added meaning in recollection, show left parietal effects (Gonsalves & Paller,
2000; Rugg, Allen & Birch, 2000). Further evidence from “remember” vs. “know” procedures
strengthen this theory. In this case “old” judgements will require participants to make a
“remembered/know” decision, when answering “old” they would also state whether the memory
was due to a feeling of familiarity (“know”) or they remembered the context surrounding the item
(“remembered”). When participants choose “remembered” for an “old” response it would most
likely be a recollection response. Correct “remembered” responses consistently reveal left parietal
effects (Wolk et al., 2006; Vilberg & Rugg, 2007; 2008; 2009; Rugg et al., 1998; Cheng & Rugg, 2004).
Conversely right frontal and FN400 old/new effects have been linked to familiarity responses
(Wilckens et al., 2011; Curran & Cleary, 2003; Curran, 2004; for review see Rugg & Curran, 2007;
Wolk et al., 2006).
Age-related differences between the three ERP effects have only come to light recently and are not
consistent. Some studies have shown little to no age-differences between any effects (Li, Morcom &
Rugg, 2004; Mark & Rugg, 1998; Gutchess, Leuji & Federmeier, 2007). However, studies that do
show age-related differences have shown both abnormal or reduced old/new effects both at frontal
and parietal locations (Yonalinas, 2002). A study by Trott, Friedman, Ritter & Fabiani (1997) and
Trott, Friedman, Ritter, Fabiani & Snodgrass (1999) found reduced and abnormal frontal activation in
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seniors compared to younger adults linked to unsuccessful retrieval which provides support that
frontal lobe dysfunction, specifically strategic deficits, are linked with poorer recognition
performance in seniors (for review see Friedman, 2000). Studies also tend to show little age-related
differences in left parietal old/new effect (Morcom & Rugg, 2004; Duverne, Motamedinia & Rugg,
2009; Trott et al., 1997; 1999; Friedman, 2000).
While all three old/new effects could be analysed in this study, due to time constraints only the left
parietal area will be analysed. It’s recollective inclination throughout the literature will form the
basis of this thesis’ hypotheses.
Thesis Aims, Questions and Expectations
The primary objective of this thesis will be to assess whether the Cognitive Control Hypothesis or the
Memory Specificity Hypothesis, more accurately reflects the age-related changes that cause
decreased successful recollection in seniors along with increased false recognition of lure items. In
order to assess this four ERP conditions will be analysed: correctly identified repeated items (Hits,
H), correctly rejected lure items (CL), correctly rejected novel items (CN) and false alarms to lure
items (FA).
This study aims to further investigate age-related decline in recognition by adapting Koutstaal’s
(2006) false recognition experiment, which demonstrated high false recognition performances in
young and senior adults using picture stimuli. In addition, Ally, Waring et al. (2008) and Morcom &
Rugg (2004) found old/new ERP effects were strongest in picture conditions, reflected by an
increased behavioural performance for pictures than words. If true, an ERP study based on picture
stimuli would be more likely to elicit old/new effects and thus contrast the CCH and MSH
hypotheses.
Koutstaal’s (2006) study used picture stimuli in a randomly cued recognition test with item-specific
and category-based judgements (see figure 1). Participants would implicitly encode pictures by using
a size-judgement task by indicating after each picture whether the real-world counterpart of the
object would fit into a small box (example box provided at the start), after which participants would
make “old” versus “new” recognition judgments on repeated, novel and similar (i.e. lure) pictures.
Moreover, participants were instructed to make their “old/new” decisions for each picture based on
whether the picture was seen before (item-specific) or another picture from the same category was
seen before. Koutstaal (2006) found that, like previous experiments, seniors could move between
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Examination Number: 7879463
item and category levels, flexibly making use of gist memory. However, seniors’ performance
decreased when presented with lure items (i.e. the sitting duck in Figure 1) compared to younger
adults.
In this study participants will undergo a self-paced, forced-choice picture recognition task using
pictures from Koutstaal’s study along with new, original pictures.
Representation of Koutstall (2006) paradigm and example stimuli used.
Study Phase
Stimuli
Test Phase
Stimulus
Correct
Type
Response
Category
Repeated
Old
Item
Repeated
Old
Category
Similar
Old
Item
Similar
New
Category
Novel
New
Item
Novel
New
Instruction
Stimuli
Figure 1. Schematic representation of study and recognition tasks used by Koutstaal (2006).
Participants at study would implicitly memorise items by performing a size-judgment task. At test,
previous items would be grouped by either category or single-item: using this indication participants
would need to make a judgment on whether the item presented was “old”, “similar” or “new”. NB:
Pictures in Koutstaal’s (2006) study were presented in colour.
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Examination Number: 7879463
In both the CCH and the MSH younger adults will show similar left parietal old/new (recollection)
effects for both Hits and CL as they will be using strategic processing (i.e. ‘recall-to-reject’ and the
‘distinctiveness heuristic’) to correctly recall original stimuli (Duverne et al., 2009; Trott et al., 1997;
1999; Friedman, 2000; Yonalinas, 2002). They will also show similar left parietal effects for FA and CR
as both conditions use familiarity process: in the CR condition young adults will correctly use
familiarity to correctly reject novel items while in the FA condition they will over-rely on this nonspecific feeling of familiarity and incorrectly accept the lure item as “old” (Dodson & Schacter, 2002;
Odegard & Lampinen, 2005; Gallo et al., 2006). In this respect:
Hits = CL > FA = CR
However, in seniors if the CCH holds true they will encounter a failure in strategic processing. Seniors
will tend to not recollect lures due to impairments in recall-to-reject and/or the distinctiveness
heuristic and thus will not reject lures (Gallo et al., 2006; Dodson & Schacter, 2002). Instead seniors
will over-generalise original stimuli and incorrectly accept lures on a familiarity basis. With CR
seniors will also not recollect items, instead rejecting new items due to their unfamiliarity. When
seniors correctly identify lure stimuli as similar they will not recollect original item, instead rejecting
the lure due to its unfamiliarity (Koutstaal, 2006, Odegard & Lampinen, 2005). Consequently a left
parietal old/new (recollection) effect will not be seen FA, CR or CL. Such that:
Hits > CL = FA = CR
If the Memory Specificity Hypothesis is accurate then seniors will encounter a failure in pattern
separation where high levels of overlap will occur between items such that the correct recollection
of specific, distinctive items will be impaired (Toner et al., 2009; Gilbert et al., 2001). Seniors will
instead fully and confidently recollect items, however, they will not recollect them specifically
enough to differentiate lure items from repeated items (Chua et al., 2009; Lyle & Johnson, 2006;
Dodson et al., 2007). Such that:
Hits = CL = FA > CR
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Examination Number: 7879463
Method
Participants
Behavioural Pilot Study: Thirteen participants were from two age groups of 18-35 years (N=9) and
62-79 years (N=4). Participants were either university students or retired professionals. Other
inclusion criteria were: an ability to use a computer and read English, normal or corrected-to-normal
vision. The experimental procedure for the pilot study was approved by the Psychology Research
Ethics Committee of the University of Edinburgh (PREC). All participants were naïve to the design
and aims of the study. Pilot participants received £6 in payment.
ERP Study: Forty-six participants were assessed within the two age groups of 18-35 years (N=22) and
62-79 years (N=24). The younger group had an average age of 25 (standard deviation, SD = 3.66)
years and the older group of 71 years (SD = 5.98). A summary of participant characteristics is listed in
Table 1. Additional exclusion criteria were applied; right handedness was required and an of health
conditions believed to influence their neurological status or future ERP recording. Health problems
excluded, included: drug and alcohol abuse, vascular conditions, brain surgery, open heart and
bypass surgery, diabetes with complications, head injuries incurring more than an overnight hospital
admission or a psychiatric illness requiring repeated treatment.
Participants in the ERP study also completed a standardized battery of neuropsychological tests
which investigated cognitive functions associated with memory, ageing or both (shown in the
neuropsychological tests section). No participants were excluded due to low scores in the
neuropsychological tests.
However, 22 participants were excluded from the group ERP analysis (seniors N=9; young adults
N=15) . This was due to computer malfunction (N=3); bad quality EEG data (N=5) and inadequate
behavioural performance which resulted in too few trials in one of the critical experimental
conditions (repeated hits; correct novel rejections; correct lure rejection and lure false alarms:
N=14).
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Examination Number: 7879463
The experimental procedure for the ERP study was approved by the Psychology Research Ethics
Committee of the University of Edinburgh (PREC). ERP participants were paid £25 and were naïve to
the design and aims of the study.
Neuropsychological Tests
These tests were completed in a separate session within 1 week of the EEG experiment. The
neuropsychological tests included: the Mini Mental State Examination (MMSE; Folstein, Folstein &
McHugh, 1975), a brief assessment of general cognitive functioning used a general screening where
a minimum of 25/30 was required for the inclusion in the study (Mitchell, 2009); the Hospital
Anxiety and Depression Scale (HADS) (Zigmond & Snaith, 1983), a basic measure of anxiety and
depression; the Trail Making Task (TMT; Reitan, 1958; 1992), a measure of processing speed, mental
flexibility and executive function; the Wechsler Test of Adult Reading (WTAR; Wechsler, 2001), a
measure of verbal IQ; two sub-test of the Wechsler Adult Intelligence Scale (WAIS-IV; Wechsler,
2010) called Digit Span, a measure of attention, and Symbol Coding, a measure of visual perception,
speed and executive function.
Design
The experiment used a within-items and between-subjects design; participants undertaking two
explicit forced choice tasks based on picture items developed from Koustaal’s (2006) study.
Participants would unintentionally study picture stimuli by answering a size-judgment task. They
could answer “yes” or “no” but this factor was disregarded during analysis, as it was irrelevant to our
study aims. After studying the items (each shown once) participants would undergo a recognition
test and could answer either “old” (repeated), “similar” (lures) or “new” (novel) to picture stimuli.
Materials
Behavioural Pilot Study: Consent forms were used (Appendix A) along with a personal laptop; an
MSI X610 with a 15.6 inch screen size and 1366x768 resolution. Six programmes were designed using
Cogent2000 software (version 1.29: see reference Cogent 2000) running on MATLAB (version 7.10.0
R2010a: MATLAB) which both ran the experiment and recorded responses.
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Examination Number: 7879463
ERP Study: In addition to consent forms (Appendix A), basic information forms were used in the EEG
procedure (Appendix B). The basic information forms included the health screening questionnaire
and questions on: age, gender, education status, vision status and native language. Two information
forms were designed which laid out instructions to the size-judgement task (i.e. study phase) and the
memory recognition task (i.e. test phase) (Appendix C). A small shoebox (approx. 8 inches by 16
inches by 5 inches) was used to help participants visualise how large the space was for objects to
possibly fit into for the size-judgement task. A hand-chart (Appendix D) was also used to show
participants how to place their hands when undertaking the procedure. One programme was
developed using the software package Psychtoolbox (version 3.0.9: Psychtoolbox; Brainard, 1997;
Pelli, 1997) running of MATLAB (version 7.10.0 R2010a: MATLAB) which ran the experiment.
Procedure
The paradigm comprised of two explicit forced choice tasks based on picture stimuli; a study phase
size-judgment task and a test phase recognition task where pictures could either be repeated from
the study phase, novel or similar items (i.e. “lures”) (see figure 1). The pool of stimuli and expected
performance were evaluated in the behavioural pilot study which led to the following procedure
being developed (Appendix E).
In total 1,014 picture stimuli were used as trials in the EEG experiment; of which 611 were updated
or duplicated stimuli from Koutstaal’s (2006) study. These pictures were detailed line drawings or
coloured photographs based on common objects and animals. Trials were counterbalanced so that
each item (excluding practice stimuli) was presented in repeated, similar and novel conditions at
study and test. This resulted in six versions of the programme being developed. Each version
contained 324 trials at study and 484 at test. Within both tasks 4 trials were used as fillers. Two
fillers were shown at the start and two were shown at the break and if a participant paused the
programme.
At study 160 items were shown as to-be-repeated trials and 160 were trials shown only once in the
experiment. Within the test phase 160 trials were repeated items from the study phase; 160 trials
were novel items, and 160 trials were items matched as “similar” to trials at study which were not
repeated. Trials which were a matched “similar” pair would have the same title (e.g. light bulb) but
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Examination Number: 7879463
would be different brands, breed of animal, colours, orientations, one could be a line drawing and
the other a photograph, etc. An example of this design can be seen in Figure 2.
Design and Picture Stimuli
Phase of experiment
STUDY
TEST
Type of
Item
Stimulus
Type
Correct
Response to
Item
Old
Repeated
Old
New
Lure
Similar
New
Novel
New
Figure 2. A schematic representation of the study and recognition tasks: Participants were shown
items which they would make a size-judgement decision and implicitly study and in a later
recognition task (test) they would decide whether items had been repeated, were only similar to
original items or completely novel.
Twenty items presented as practice for the size-judgement task and 30 items presented for the
recognition memory task. Practice programmes were designed to be consistent with the two tasks.
At study, 10 items were to-be-repeated and 10 shown only once. At test practice, 10 items were
repeated trials from the practice study phase, 10 items were novel trials and 10 items were lure
trials.
Each trial (including fillers) was interspersed with a fixation point “+”. Trials were self-paced.
Participants could respond either with the picture on-screen or after it had been displayed where
the black “+” sign show. At study, pictures were displayed for a maximum of 2 seconds with
maximum response time where a black “+” sign was displayed for 7 seconds. At test, pictures were
displayed for 500ms with a maximum response time of 5 seconds. After a participant response the
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Examination Number: 7879463
sign started black, turned red and then disappeared to show the next picture. This response-stimulus
interval was 1 second with the black “+” was displayed for 100ms changing to the red for 500ms.
The background to all screens was white. Text was in Arial font, size 40. All pictures were shown in
white box 150mm by 135mm. Pictures also covered approximately the same area inside this box.
At the start of the experiment participants underwent EEG preparations after which they were
seated 90cm in front of the computer monitor. They were raised so that they would be eye-level
with the fixation point to ensure minimal eye movement. Participants were randomly allocated,
viewing one of the six versions of the study/test programmes. The experiment was counterbalanced
with a approximately equal distribution of participants doing each version.
Instructions at the start of the both tasks (Appendix C) informed participants how to complete those
tasks. The study phase was first. Here participants were given the “Picture Decision Task”
instructions and after reading them, the experimenter also explained the task. The objective was to
view the pictures on screen and after each decide whether its real-world counterpart would fit
inside the small box presented. Two keys were shown on the keypad “A” and “L”. Both keys were
covered by white stickers to differentiate them from the rest of the keypad. Using a hand-chart
(Appendix D) participants were shown which key marked “YES” and which key marked “NO”. This
was counterbalanced so that approximately half of participants pressed “A” for “YES”; “L” for “NO”
and vice versa. All participants were informed they could press the “P” button to pause the
programme if they needed a break. Participants were also advised to stay as relaxed as possible
while keeping head and eye movements to a minimum and focusing on the picture or “+” when
appropriate. Participants were given the opportunity to ask questions after which the box and
instruction sheets were removed and the practice study phase programme was started.
Once the practice trials were completed participants were again given an opportunity to ask
questions before the study phase was started. At the end of the study phase all participants had a 10
to 15 minute break.
Participants were next given the instruction sheet for the test phase (Appendix C). The objective was
to watch pictures on screen, for each picture they would decide whether it was repeated (“old”),
similar or novel (“new”). It was explained that a similar picture would be one in where a picture on
the first task had the same name (i.e. dog, pitcher, deck chair), however, it would be different (i.e.
coloured differently; be different breeds of animal; different orientations, etc). Participants were
shown the hand-chart demonstrating buttons to be used for “OLD”, “SIMILAR” and “NEW”
(Appendix D). As at study, response keys were marked with white stickers over the “C”, “B” and “M”
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Examination Number: 7879463
keys. Keys were counterbalanced so that approximately half of participants would press “C” for old;
“B” for similar and “M” for new while the other half would press “M” for old; “B” for similar and “C”
for new.
Once the recognition task was completed the EEG cap was removed and participants were paid,
debriefed and thanked. All participants completed the procedure.
ERP Recording and Pre-processing
Participants wore the 10-20 electrode cap configuration with 64 channels. Six other channels were
placed: one on the horizontal canthus of each eye, and one vertically above and below the right eye,
in order to track eye movements and blinks, along with two on the mastoids to be used as a linked
reference. The initial EEG recording was done at a ~1kHz sampling rate with a BioSemi amplifier. Low
pass filtering was conducted at ~100Hz using a ADC’s decimation filter with a 5th order sinc response
and -3dB point at the 1/5th of the sampling rate on raw participant files. After data collection, an
average of the two mastoid electrodes served as a reference and epoched data was further filtered
with high-pass filtering at 0.3Hz and low-pass filtering at 20Hz. Blink artefacts, vertical and horizontal
eye movements were analysed using independent component analysis (ICA) and were automatically
removed using ADJUST (Mognon, Jovicich, Bruzzone & Buiatti, 2010). ERPs intervals were initially
calculated at a -2000ms to 2500ms with a -2000ms baseline then narrowed to -500ms to 2500ms
with a -500 baseline for each subject in each stimuli category (repeated, lure and novel) and
response type (old, similar and new). EEG pre-processing, ERP construction and statistical analysis of
ERP magnitude and topography was conducted in EEGLAB (Delorme & Makeig, 2004; Delorme,
Sejnowski & Makeig, 2007).
Before participants started the study and test tasks they were asked to keep head and eye
movements to a minimum while focusing on the picture and “+” when they were on screen. An
opportunity to ask questions was then given after which the instruction sheets were removed and
the practice test phase programme was started. After the practice trials participants were given the
opportunity to ask the experimenter any questions they had about the task presented before the
test phase programme was started.
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Examination Number: 7879463
Results
Neuropsychological Test Performance
The results from the neuropsychological test battery are summarized in Table 1. This table includes
p-values from independent t-test using age-group as a between-group factor. Results indicate
significant differences in the Wechsler Test of Adult Reading with seniors’ performing at a higher
level; the Wechsler Adult Intelligence Scale Digit Span sub-test, forward and backwards, with
younger participants performing higher in both parts; the Trail Making Task part A and B with
younger participants faster, and the anxiety component of the Hospital Anxiety and Depression scale
where younger participants were identified as more anxious than senior participants.
Table 1. Participant characteristics and performance on the neuropsychological test battery
Younger (n = 17)
Senior (n = 16)
t-test
P
-28.08
< .001
9 Female, 7 Male
-
-
3, 5, 8*
-
-
M
SD
M
SD
Age
24.7
3.5
71.7
5.9
Gender Distribution
9 Female, 8 Male
2, 1, 14*
Education Distribution
MMSE
Digit Span
29.1
1.4
28.9
1.8
0.4
n.s.
Forwards
7.2
1.1
8.4
0.6
-2.4
< .001
Backwards
5.5
1.6
6.7
1.1
-2.4
< .05
44.8
4
48
2.2
-3.84
< .05
A
25.2
8.6
32.1
9.7
-2.17
< .05
B
49.7
23.3
80.2
41.1
-2.64
< .05
6.4
2.6
5.5
2.4
0.3
n.s.
Anxiety
6.2
3.6
3.9
1.9
-2.18
< .05
Depression
2.7
2.1
2.5
2.2
0.35
n.s.
WTAR
TMT
Digit Symbol
HADS
Mean (M) and standard deviation (SD) for younger and senior adults including significant results. T-test
performed at 25 degrees of freedom. Note: n.s. means ‘not significant’ (p > .05)
*Numbers correspond to Secondary schooling, 1st Degree, 2nd Degree
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Examination Number: 7879463
Behavioural Analysis Strategy
The dependent measures analysed were: proportion in answering old/similar/new to
repeated/lure/novel stimuli and time duration from mean response time (RT) per condition using
analysis of variance (ANOVA) with Greenhouse-Geisser as a test of sphericity. Following Toner et al.
(2009) differences between the two age groups were assessed on correctly answered trials (H, CL
and CR). After this group differences within error responses on lure trials was as FA (old responses
for lure trials) is also a critical condition in this thesis’ hypotheses. Measures of accuracy and
response bias were also analysed using several well known indexes (Pr, PrSim, Pattern separation, Br)
to further understand age-related differences in the ability to discriminate between repeated and
novel stimuli.
Experimental task performance

Accuracy analysis
The mean proportion of old, similar and new responses to repeated, lure and novel stimuli for both
age-groups are shown in Figure 3. A 2x3 ANOVA was conducted with age-group as a between-group
factor and trial type (old, similar and new) of correct responses as a between-subject factor. This
revealed a significant main effect of trial type (F(1.8, 55.9) = 36.77, p < .001), a main effect of group (F(1,
31)
= 9.01, p < .05), shown in Figure 4.
Mean proportion of responses for repeated, lure and novel stimuli
Repeated Stimuli
Lure Stimuli
Novel Stimuli
Figure 3. The mean proportion of old, similar and new responses (including standard errors; SE) to repeated,
lure and novel stimuli. Note: error bars are +/- 2 SE.
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Examination Number: 7879463
Accuracy according to proporitons of correct trial type by group
Figure 4. The mean proportion of trial type (correct old/similar/new responses) by group. Note: error bars are
+/- 2 SE.
An independent t-tests based on trial type (old, similar and new) of correct responses by age-group
showed significant differences in the similar response condition (t(31) = 3.33, p < .05) with younger
participants performing better (M = 0.48, SD = 0.14) than senior participants (M = 0.33, SD = 0.12)
and a trend effect in correct old responses (t(31) = 2.02, .05 < p < .1) where younger participants
looked to be more accurate (M = 0.71, SD = 0.13) than senior participants (M = 0.62, SD = 0.14).
Three follow-up mixed-model ANOVAs were calculated to compare age-group (young vs. senior) by
the 3 pairs of trial types (old vs. similar; similar vs. new; old vs. new correct responses). The first 2x2
mixed-model ANOVA factors age-group and trial type (old vs. similar) showed a significant main
effect of trial type (F(1, 31) = 84.41, p = .001) and a significant main effect of group (F(1, 31) = 11.23, p =
.001). Here, younger adults performed better (Mold = 0.71, SDold = 0.13; Msimilar = 0.48, SDsimilar = 0.14)
than senior participants (Mold = 0.61, SDold = 0.14; Msimilar = 0.33, SDsimilar = 0.12) and all participants
were more accurate for old items (M = 0.66, SD = 0.14) than for similar items (M = 0.41, SD = 0.15).
A 2x2 mixed-model ANOVA with age-group and trial type (simlar vs. new) showed a significant main
effect of group (F(1, 31) = 6.29, p = .05), a significant main effect of correct response type (F(1, 31) =
41.89, p = .001) and a significant interaction (F(1, 31) = 4.74, p = .05). Here, younger adults performed
better in the lure condition with a higher proportion of correct (similar) responses (Msimilar = 0.48,
SDsimilar = 0.14 vs. Msimilar = 0.33, SDsimilar = 0.12) while senior adults performed beter in the novel
condition with a higher proportion of correct (new) responses (Mnew = 0.65, SDnew = 0.13 vs. Mnew =
0.64, SDnew = 0.13). All participants performed higher with correct new responses (M = 0.65, SD =
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Examination Number: 7879463
0.14) than with correct similar responses (M = 0.41, SD = 0.15). A 2x2 ANOVA with age-group as a
between-subject factor and correct response type (old vs. new) showed no significant effects.
To compare differences in types of error for lure stimuli between age-groups a mixed-model 2x2
ANOVAs was calculated with factors age-group (young vs. senior) and error type (old vs. new
responses). Results showed only a significant main effect between group (F(1, 31) = 10.95, p = .05)
where youger participants showed fewer errors in both conditions (Mold error = 0.26, SDold error = 0.09;
Mnew error = 0.26, SDnew error = 0.13) than senior participants (Mold error = 0.33, SDold error = 0.13; Mnew error =
0.34, SDnew error = 0.13).

Response times analysis
The mean reaction times (RT) of old, similar and new responses to repeated, lure and novel stimuli
for both age-groups can be seen in Figure 5. RT were measured in a 2x3 ANOVA factors age-group
(young vs. senior) and trial type (old, similar and new) for correct responses. This revealed no
significant main effects. However, independent t-tests of trial type (old, similar and new) in correct
responses by age-group showed significant differences for old trials (t(31) = -2.87, p < .05) with
younger participants answering faster (M = 1102, SD = 156) than senior participants (M = 1296, SD =
229) and significant age differences for similar trials (t(31) = -3.69, p < .001) with younger participants
answering faster (M = 1364, SD = 238) than senior participants (M = 1696, SD = 277).
Mean Reaction Time of responses for repeated, lure and novel stimuli
Repeated Stimuli
Lure Stimuli
Novel Stimuli
Figure 5. The reaction times for old, similar and new responses (including standard errors; SE) to repeated,
lure and novel stimuli. Note: error bars are +/- 2 SE.
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Examination Number: 7879463
Three follow-up mixed-model ANOVAs were calculated to compare RT differences between agegroup (young vs. senior) by the 3 pairs of trial types (old vs. similar; similar vs. new; old vs. new
correct responses). A 2x2 ANOVA with factors of age-group and trial type (old vs. similar) showed a
significant main effect of age-group (F(1,31) =14.94, p = .001) and a significant main effect of trial type
(F(1,31) = 64.57, p = .001). Here, younger adults responded faster (Mold = 1102, SDold = 156; Msimilar =
1365, SDsimilar = 237) than senior participants (Mold = 1296, SDold = 229; Msimilar = 1695, SDsimilar = 277)
with all participants responding faster in the old response condition (M = 1196, SD = 215) than in the
similar response condition (M = 1525, SD = 304). A 2x2 ANOVA with factors age-group and trial type
(simlar vs. new) showed a significant main effect of group (F(1,31) = 6.67, p = .05), a significant main
effect of correct response type (F(1,31) = 32.39, p = .001) and a significant interaction between trial
type and group (F(1,31) = 11.76, p = .05). Here, younger adults responded faster (Msimilar = 1365, SDsimilar
= 237; Mnew = 1304, SDnew = 289) than senior participants (Msimilar = 1695, SDsimilar = 277; Mnew = 1453,
SDnew = 303) with all participants responding faster in the new response condition (M = 1377, SD =
300) than in the similar response condition (M = 1525, SD = 304). A 2x2 ANOVA with factors agegroup as and trial type (old vs. new) showed a significant main effect of trial type (F(1,31) = 19.36, p =
.001) where both groups were faster in the old response condition (M = 1196, SD = 215) compared
to the new response condition (M = 1377, SD = 300) and a significant group effect (F(1,31) = 4.97, p =
.05) where younger participants responded faster (Mold = 1102, SDold = 156; Mnew = 1304, SDnew =
289) than senior participants (Mold = 1296, SDold = 229; Mnew = 1453, SDnew = 303) when correctly
answering old and new.
To compare differences in types of error for lure stimuli between age-groups a mixed-model 2x2
ANOVAs was calculated with factors age-group (young vs. senior) and error type (old vs. new
responses). Results showed no significant effects.

Discrimination and response bias analysis
Accuracy discrimination between stimuli and response bias was calculated using proportion results
for each response condition, displayed in Table 2. To measure discrimination between repeated and
novel stimuli the discrimination index Pr (H - old response to novel items) and d’ (Snodgrass &
Corwin, 1988; Ally, Simons et al., 2008) was used. An independent t-test with age-group as a
between-group factor both Pr and d’ revealed significant differences in age-group with younger
adults showing enhanced discrimination compared to seniors. In addition a discrimination index
analogous to Pr for H versus FA was calculated (PrSim) along with an index for pattern separation (PS
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Examination Number: 7879463
where CL - similar response to novel items) was calculated using an independent t-test with agegroup as a between-group factor (Toner et al., 2009). Both PrSim and PS revealed significant agegroup differences with seniors showing poorer ability to discriminate between similar vs. old items
and similar vs. new items compared to younger adults. Response bias (Br) was also measured
(Snodgrass & Corwin, 1988) using an independent t-test using age-group as a between-group factor.
No significant differences was shown between the two age-groups.
Table 2. Discrimination and response bias
Younger (n = 15)
Senior (n = 12)
t-test
P
0.14
2.69
< .05
1.18
0.64
2.82
< .05
0.15
0.28
0.13
3.37
< .05
0.21
0.14
0.11
0.1
2.42
< .05
0.2
0.13
0.25
0.13
-1.05
n.a.
M
SD
M
SD
Pr
0.63
0.16
0.49
d’
2.08
1.12
PrSim
0.45
PS
Br
Mean (M) and standard deviation (SD) for younger and senior adults including significant result for Pr (H vs.
“old” response to novel items), PrSim (Hits vs. FA), PS (CL vs. “similar” response to novel items) and response
bias (Br). Within response bias positive values of C indicate a conservative bias while negative values indicate a
liberal bias. Note: n.a. means ‘not significant’. T-test performed at 25 degrees of freedom.
ERP Analysis Strategy
Due to the small group sizes, an exploratory analysis of magnitude over the left parietal scalp (shown
in Figure 6) was conducted. This analysis included data from eight electrodes: TP7, CP5, CP3, CP1, P1,
P3, P5 and P7. The time interval of 450 to 800ms was chosen based both on previous research
(Curran, 2004; Rugg & Curran, 2007) and on visual inspection of the grand mean average waveforms
for young adults and seniors (Figure 7 and 8). The four critical conditions which will be compared
are: correct hits (H), correct lure rejections (CL), correct new rejections (CR) and false alarms to lure
items where participants answer “old” (FA). First, a non-parametric permutation on the mean ERP
waveforms was conducted in the time interval -200 to 1500ms (alpha = 0.05,uncorrected for
multiple comparisons; Delorme & Makeig, 2004). Further post-hoc pair-wise comparisons (alpha =
0.05, uncorrected for multiple comparisons) using non-parametric permutations were computed to
analyse the differences between the critical conditions for each age-group in the 450 to 800ms time
interval: H vs. CR; H vs. CL; H vs. FA; CR vs. CL; CR vs. FA and CL vs. FA (Delorme & Makeig, 2004).
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Examination Number: 7879463
64 electrode cap with electrodes used for analysis of left parietal effects
Anterior
TP7 CP5
P7
P5
CP3 CP1
P3
P1
Posterior
Figure 6. Area of interest on the left parietal scalp consisting of TP7, CP5, CP3, CP1, P1, P3, P5, P7 electrodes.
ERP Data
Grand average ERP waveforms are shown for each group from the selected electrode sites in Figures
7 and 8. The mean number of trials in each condition yielding each subject’s waveforms is shown in
Table 3.
Table 3. Trial numbers for each condition used in ERP analysis
Younger (n = 15)
Senior (n = 9)
M
Range
M
Range
H
110
55 – 136
98
66 – 128
FA
38
19 – 69
48
21 – 90
CL
71
41 – 105
48
30 – 72
CR
97
46 – 141
96
57 – 144
Mean and ranges for trial numbers in correct old responses (H); lure false alarms where participants answered
“old” (FA); lure correct rejections where participants answered “similar” (CL); and new correct rejections
conditions.
The ERP analysis was guided by both previous research and visual inspection of the mean ERP
waveforms in the selected left parietal electrodes beginning with a non-parametric permutation on
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Examination Number: 7879463
the mean ERP waveforms in the time interval 450 to 800ms (alpha = 0.05), significant areas shown in
Figure 7 and 8. Results showed significant differences between the 4 critical conditions in the young
participant data (electrodes: TP7, CP3, CP1, P1, P3, P5) and in the senior participant data (electrodes:
TP7, CP3, CP1, P5 and P7) at multiple points. This can be seen in Figures 7 and 8.
Mean ERP waveforms from left parietal in younger adults
CP5
TP7
CR
H
FA
CL
CP3
P3
CP5
TP7
P7
CP3
P5
P3
CP1
P1
P5
P7
CP1
P1
P7
0
500
1000
Time from Stimulus Onset (ms)
0
500
1000
Time from Stimulus Onset (ms)
0
500
1000
Time from Stimulus Onset (ms)
Figure 7. Mean ERP waveforms (young adults) for the selected electrodes on left parietal scalp varying by
critical condition (CR = novel correct rejection; H = correct repeated hits; FA = lure false alarms and CL = correct
lure rejection). Note: boxes indicate regions of significant difference (time window 450 to 800ms only).
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Examination Number: 7879463
Mean ERP waveforms from left parietal in senior adults
CP5
TP7
CR
H
FA
P7
CL
CP3
P3
CP5
TP7
CP1
P1
P5
P7
P5
CP3
CP1
P3
P1
P7
0
500
1000
Time from Stimulus Onset (ms)
0
500
1000
Time from Stimulus Onset (ms)
0
500
1000
Time from Stimulus Onset (ms)
Figure 8. Mean ERP waveforms (senior adults) the selected electrodes in left parietal scalp varying by critical
condition (CR = novel correct rejection; H = correct repeated hits; FA = lure false alarms and CL = correct lure
rejection). Note: boxes indicate regions of significant difference (time window 450 to 800ms only).
To further analyse differences found in general non-parametric permutations, specific post-hoc pairwise comparisons were computed between the critical conditions (H, CL, CR and FA) in the 450 to
800ms time interval for both groups. While effects are weak due to the small number of
participants, differences have been noted between critical conditions.
In young adults a pair-wise comparison of H vs. CR showed the most significant difference in the
time window. Differences were demonstrated in electrodes TP7, CP3, CP1, P1, P3 and P5, specifically
in the 600 to 800ms region where H were seen as a more positive-going waveform compared to CR.
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Examination Number: 7879463
A comparison of H vs. FA showed significant differences in the TP7, CP1 and P1 electrode between
550 and 800ms, however, H in this case showed more negative-going waveforms than FA. A
comparison of H vs. CL showed little significant differences with TP7 (450-500ms) and P1 (750800ms). In these cases CL showed more positive-going waveforms. A comparison of CR vs. FA
showed significant differences in the P5, P3 and P1 electrode from 450 to 500 and 600 to 750ms. A
comparison of CR vs. CL revealed differences in CP5, CP3, P3 and P7 electrodes from 600 to 700ms
with CL showing more positive-going waveforms. A comparison of CL vs. FA showed little difference
between conditions, CP1 and P1 electrodes showed (450 to 470ms) CL as more positive-going
waveforms than FA. Taking into account the greatest differences between conditions, in young
adults:
FA > H = CL > CR
The same method of pair-wise comparisons was conducted for senior participant data. A pair-wise
comparison of H vs. CR showed in- significant difference between the two conditions. A comparison
of H vs. FA showed small areas of time of significant differences between the two conditions, in TP7,
CP3, P1, P3 and P7 where FA waveforms were shown to be more positive-going. A comparison of H
vs. CL showed very little differences between the two conditions. A comparison of CR vs. FA revealed
little significant differences. In TP7 some differences were found at 530-550 and 680 to 800ms
where FA were shown to be more positive-going waveforms. A comparison of CR vs. CL showed
significant differences in small areas across the TP7 electrode where CL was more positive-going
than CR. A final comparison of CL vs. FA revealed significant differences at CP3, P1, P3 and P5 where
FA was more positive-going than CL. Taking into account the greatest differences between
conditions, in seniors:
FA > H = CL = CR
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Examination Number: 7879463
Discussion
This study explored whether the Cognitive Control Hypothesis (CCH) or the Memory Specificity
Hypothesis (MSH) more accurately reflects age-related changes which have demonstrated decreased
successful recollection in senior adults compared to younger adults (Roediger & Geraci, 2007; Chan
& McDermott, 2007; Aizpurua & Koutstaal, 2010; Schacter et al., 1998). The findings from the
neuropsychological tests, behavioural and ERP analyses along with implications are discussed in the
following sections.
Neuropsychological test findings
The results from neuropsychological tests revealed both expected and unexpected performances in
the two groups. Significant age-related differences were found in the Wechsler Test of Adult Reading
(Wechsler, 2001) where seniors’ demonstrated better performances than younger adults. This is an
expected result as vocabulary and verbal IQ are not generally shown to decrease with age
(Salthouse, 2009; 2010). In addition, scores in the Trail Making Task revealed seniors to be
significantly slower than younger adults. This is also expected as decreased processing speed is one
of the most commonly viewed age-related effects (Tombaugh, 2004; Salthouse, 2010; Park et al.,
2002).
Unexpectedly, results from the Wechsler Adult Intelligence Scale (WAIS-IV; Wechsler, 2010) sub-test,
Digit Span, showed significant age-related differences in both forward and backwards assessments.
In both cases, seniors performed better than younger adults. Conversely, previous research has
found younger adults demonstrate greater Digit Span performance than seniors (Park et al., 2002).
This suggests that the two age-groups were un-matched when performing the recognition
experiment. When evaluating any potential ERP effects, age-group matching would support
conclusions (see “General Discussion” section). In addition, results from the Hospital Anxiety and
Depression Scale revealed younger adults as significantly more anxious than seniors. This also
reveals a mismatching between groups which may potentially effect ERP conclusions. The
differences between anxiety levels may be attributable to the timing of the ERP experiment. The
majority of younger participants were MSc students at the University of Edinburgh and at the time of
testing will all be in the midst of their final year thesis writing. Consequently, the timing of the
experiment may have influenced these scores.
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Examination Number: 7879463
Behavioural findings
This study supports previous behavioural findings in respect to recognition memory and ageing in
which seniors are significantly worse at discriminating between repeated and novel stimuli than
younger adults, despite similar end performances with respect to repeated and novel stimuli
(Yonelinas, 2002; Wolk et al., 2009). In addition, evidence shown here supports the suggestion that
seniors are inclined to falsely “remember” events which did not happen, by misleading post-event
information (i.e. lure items), compared to younger adults (Roediger & Geraci, 2007; Chan &
McDermott, 2007; Koutstaal, 2006; Aizpurua & Koutstaal, 2010). However, seniors were also just as
likely to falsely reject lure items as completely “new”.
When investigating age-differences in correct responses, results showed younger adults made
significantly less errors overall than senior participants. This demonstrated age-related differences in
the DRM method and supports previous research (Koutstaal, 2006; Norman & Schacter, 1997; Wiese
& Daum, 2006; Luo & Craik, 2008; Chan & McDermott, 2007). Significant differences in Pr and d’
scores (correct old responses vs. incorrectly answering “old” to a novel item) also showed that
seniors are unable to distinguish repeated and novel items as well as younger participants, despite
performance being affected only in response to lure items (Toner et al., 2009). This suggests that
age-related differences is not due to a general decline in recognition memory but rather a specific
impairment in monitoring strategies (i.e. recall-to-reject and the distinctiveness heuristic) and/or
pattern separation. Senior adults may be over-relying on a non-specific sense of familiarity,
inappropriately using gist information and/or be susceptible to a bias in pattern completion rather
than pattern separation. This would allow for senior participants to perform proficiently when
identifying repeated or novel items but would significantly impair performance in correctly
identifying lure items, such as found here.
An analysis of the types of error made by participants to lure items (incorrectly answering “old” or
“new”) revealed that senior participants made significantly more errors compared to younger adults
supporting previous research (Toner et al., 2009; Koutstaal, 2006). However, no significant effects
were found for error type. Neither group specifically answered “old” or “new” when making lure
errors, instead both occurred. Using the index PrSim, it was found that significant differences
occurred between groups in the ability to discriminate between repeated and lure items, with
seniors significantly worse than younger adults. This suggests that while seniors show deficit in the
ability to discriminate between items, they will both falsely recognise the recognise the item as “old”
along with falsely rejecting the item as completely “new”. To analyse if there was group differences
in pattern separation an index called PS was used, this compared the proportion of correct
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Examination Number: 7879463
responses to lures items (CL) to the false alarms where participants answered “old” to lure items
(FA). This revealed significant differences between groups in the ability to use pattern separation
with seniors displaying significantly decreased pattern separation inefficiency and supports previous
findings (Toner et al., 2009; Yassa et al., 2010; Wilson et al., 2005). However, both groups revealed
positive means such that both groups showed a bias towards pattern separation rather than pattern
completion. This does not support previous research. In addition, an index (Br) was used to assess
response bias between groups. This was not significant, meaning age-related differences found
between the two groups cannot be simply attributed to different response criteria.
When analysing reaction time (RT) data younger participants were shown to be faster in correctly
answering repeated and lure items than seniors. A general slowing of processing speed
demonstrated in the Trail Making Task may account for some difference, however, if so then agerelated RT differences should be present also in response to novel items. In addition, when noted
previous work has generally found significant differences in CR, not in H or CL (Li et al., 2004;
Morcom, Li & Rugg, 2007). However, since difference in accuracy scores is only seen in the lure
condition, while RT is seen in both lure and repeated conditions, it is likely that any ERP results are
not due to disparity in RT.
ERP findings
Due to the small number of participants whose ERP data could be evaluated an exploratory analysis
comparing magnitude differences between each of the critical conditions, within-groups pair-wise
comparisons were conducted. The strongest ERP effect was found in younger adults where H>CR
(correct repeated items > correct novel rejections). Since H are more likely to be due to true
recollection instead of a feeling of familiarity, H>CR demonstrates a connection between recollection
and the left parietal scalp as shown in previous research (Yonelinas, 2002; Guerin & Miller, 2009,
Wilding, 2000; Trott et al., 1999; Li et al., 2004). Within younger adults, the conclusion H = CL > CR is
unsurprising as both H and CL (correctly rejected lures) would show greater left parietal magnitudes
than CR as they would depend on recollective processes more than familiarity processes. However,
an unexpected conclusion is FA > H = CL > CR. Pair-wise comparisons also demonstrated this on
multiple electrodes across the left parietal region (TP7, CP1, P1, P3 and P5). This suggest that FA is
associated with recollection more than H/CL. An original assumption in order to fully contrast the
Cognitive Control Hypothesis and Memory specificity Hypothesis was that FA would show less left
parietal magnitude due to familiarity effects (Duverne et al., 2009; Trott et al., 1997; 1999;
Friedman, 2000; Yonalinas, 2002). It also doesn’t support previous findings in younger adults where
H > FA (Gutchess et al., 2007). It is possible that with increased ERP data FA magnitudes will not be
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Examination Number: 7879463
significantly different from H or CL or may be equivalent to CR as was originally predicted. However,
the results from the sample gathered shows significant increases. It is possible that FA elicit
recollection effects as younger adults demonstrate failures of pattern separation when falsely
recognising lure stimuli as “old”. However, PS (the pattern separation index) demonstrated positive
results in younger adults indicative of a bias towards pattern separation compared to pattern
completion. This suggests that pattern separation where full recollection is made (with an
incorrect/less detailed item) cannot be the full explanation of the significant magnitude difference
between FA and the other critical conditions.
Results from Senior ERP data also revealed unexpected conclusions: FA > H = CL = CR. While direct
group comparisons were not conducted there appeared to be a diminished effects as H, CL and CR
all equated one another. Whereas diminished ERPs have been found in senior adults compared to
younger adults, the majority of research show H, similar to younger adults, to be greater in
magnitude over the left parietal scalp than CR (Wolk et al., 2009). In addition, the same question of
FA demonstrating significantly greater magnitudes than all other conditions was apparent in senior
ERP data. Significant age-related differences were found in the PS index revealing that older adults
were less efficient at patter separation than younger adults. However, similar to younger adults, PS
demonstrated positive results which suggested a bias towards separation compared to pattern
completion. Consequently it is unlikely that a pattern separation deficit can account for the
significant differences between FA and the other critical conditions.
Comparisons of CR and CL in senior ERP data revealed no significant differences. If true, this would
suggest support for the CCH. Accompanying the CCH hypothesis, CR are unlikely to be due to
recollection, instead seniors will reject new items due to their unfamiliarity. Also, when seniors
correctly identify lure stimuli as similar they will not recollect original item, instead rejecting the lure
due to its unfamiliarity (Dodson & Schacter, 2002; West, 1996; West, 2000; Gallo et al., 2006).
However, in the CCH hypothesis FA will also not show recollection effects (i.e. H > FA). However, the
data suggest that FA > H. This would mean that lures are recollected and so incorrectly answered as
“old” while correct repeated items are correctly answered “old” but by using more familiarityrelated processes, similar to correctly rejecting novel items.
General Discussion
The primary purpose of the experiments was to evaluate which of the two hypotheses (MSH or CCH)
more suitably explained age-related differences found in recognition memory. With regard to this
aim neither hypothesis at this time can be adopted. There is evidence for inefficient pattern
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Examination Number: 7879463
separation in seniors adults compared to younger adults within the behavioural data. There is also
evidence of diminished ERP effects in seniors (i.e. where H = CL > CR in young, in seniors H = CL = CR)
such that seniors correctly reject lures by use of familiarity measures (similar to correctly rejecting
novel items) which is in accordance with the CCH, however, not all the assumptions in the CCH are
met (i.e. H > CR). In particular, neither hypothesis can accurately explain the conclusion that both
age groups show a significant increase magnitude for FA than all other critical conditions (H, CL and
CR).
Nevertheless, the ERP results posed here are exploratory in nature only. None of the effects shown,
including the largest effect of H > CR in younger adults, remains significant once correcting for
multiple comparisons. More data will be needed to ensure the conclusions here are genuine results.
This should be done both by increasing the number of participants and increasing the number of
trials per condition (i.e. >460). While piloting this experiment allowed for an estimation on the
number of trials needed, participants in the experiment generally performed better than pilot
participants. Consequently trials in the FA condition were particularly low in many participants.
In keeping with ethical principles all participants were offered relaxation periods within the
recognition test and between the study and test phase of the experiment . In addition, no
participants complained of fatigue. In future studies, it is expected that the expansion of study/test
items for each condition could easily be achieved. Once a larger sample of data is gathered,
statistical group comparisons with ERP effects can be computed along with topographic maps which
can investigate potential negative waves from other scalp regions which may be diminishing any ERP
effects found here.
It is also worth noting when comparing groups (i.e. seniors and younger adults) disparities in
performance may impact upon ERP analysis (Li et al., 2004; Morcom et al., 2007; Duverne et al.,
2008; Wolk et al., 2009; Friedman, 2003). In this study performance was equated for novel items but
not for lure items and a trend effect was evident for repeated items. In addition, significant
differences within the Trail Making Task where seniors performed better than younger adults
suggest unequal age-matching. As performance declines on a recognition test, there is likely a
greater number of H, CR and CL that are correlated with ‘lucky guesses’ (Wolk et al., 2009). This can
effectively dilutes response categories meaning that more responses are not due to recollection or
familiarity-related processes. This creates an apparent diminution of age-related retrieval effects (Li
et al., 2004; Morcom et al., 2007; Wolk et al., 2009; Friedman, 2003). This may be relevant for the
decreased left parietal effects shown in the senior group of this study (i.e. where H = CL = CR).
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Examination Number: 7879463
Additionally, there is an important difference in the method between this study and similar studies
which demonstrate left parietal old/new effects. This study investigates age-related differences
using an item recognition task while the majority of previous studies involve source memory (Trott
et al., 1997; 1999; Li et al., 2004; Morcom et al., 2007; Mark & Rugg, 1998). Due to the method of
source memory tasks, H will be more select as participants will have to answer correctly on the item
and its surrounding context. This means that compared to item recognition tasks such as this where
participants simply answer correctly on the item, source memory tasks H conditions will be
correlated more with true recollection, not guesses (Wolk et al., 2009). Furthermore, source
memory tasks are more likely to show significant left parietal old/new effects. Consequently the
diminished ERP effects found in the senior group in this study (i.e. where H = CL = CR) could be
partially due to a different methodology. Moreover, other item recognition studies have also show
diminished ERP effects in comparison to younger adults (Ally, Simons et al., 2008; Swick & Knight,
1997; Wolk et al., 2009; Walhovd et al., 2006). This suggests that in item recognition tasks, retrieval
may associated with less detailed recollection and familiarity-processes (Wolk et al., 2009).
Despite the limitations in the ERP data, the design of the experiment worked well. Behavioural data
clearly demonstrated that seniors are significantly worse at differentiating between repeated and
novel stimuli compared to younger adults. Seniors were also significantly worse at differentiating
repeated and lure stimuli and demonstrated significantly greater inefficiency when performing
pattern separation. Thereby replicating and extending previous work in this field (Roediger & Geraci,
2007; Chan & McDermott, 2007; Koutstaal, 2006; Aizpurua & Koutstaal, 2010; Toner et al., 2009;
Yassa et al., 2010; Wilson et al., 2005). The design of the experiment could also easily be repeated.
In future experiments it would be worth ensuring greater generalisbility by using a wider sample of
the population. All participants in this study were students and recently graduates from the
University of Edinburgh or otherwise from volunteer groups within the University. Further
replication of our work with a wider, larger sample of the population with the application of added
trial numbers would help enhance our results and findings. It would also be beneficial to investigate
possible frontal ERP effects such as the FN400 and right frontal effect. This could not be done within
this study due to time constraints, however, further analyses can be done using this study with data
collected from frontally located electrodes.
Finally, using the conclusions derived in this study allows for the development of better techniques
for investigating age-related decline in recognition and increases in false memory. False recognition
can have important implications in everyday life as in eyewitness identifications, where one persons
actions can be mistakenly attributed to an innocent party (Schacter, 1999). One famous account of
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Examination Number: 7879463
this involved a well-respected psychologist called Donald Thompson who was accused of rape on the
basis of a detailed eyewitness testimony from the victim. It later transpired that the victim had been
watching a programme where Thompson had been interviewed before the event occurred and had
mistakenly replaced the rapists image with the image of Thompson from the television. While
Thomson was fortunate to have airtight alibi, this will not always be the case (Thompson, 1988;
Schacter, 1999). If false recollection is caused by pattern separation, the MSH suggests that seniors
will recall the erroneous information with high confidence (Dodson et al., 2007; Lyle & Johnson,
2006; Chua et al., 2009). If true, false recollections will be even more problematic as high confidence
can influence others believing the erroneous information, as shown in mock-juries (Cutler, Penrod &
Dexter, 1990). In addition, high rates of “gist-based” processing suggested by the CCH may over the
course of time may cumulatively make it more difficult to access specific information and compound
problems in instances such as depression (Koutstaal & Cavendish, 2006; Williams & Dritschel, 1992;
Tun et al., 2003). Furthermore, research into the processes underlying false recognition will support
dementia research which current goal is to search for early markers for disease onset and to
dedifferentiate these markers with normal, healthy ageing (Toner et al., 2009; Yassa et al., 2010).
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Examination Number: 7879463
Conclusion
This study provides behavioural evidence that seniors discriminate poorly between repeated and
novel stimuli compared to younger adults including being more likely to mislabel post-event
information as “old”. An exploratory analysis of left parietal old/new effects from collected ERP data
revealed unexpected conclusions where false alarms to lure stimuli showed significantly greater
magnitudes compared to all other critical conditions in both age groups. This is not supported by
previous research. However, younger participants showed greater correct responses to old items
with greater magnitudes than correctly rejected new items which is supported by previous research.
All ERP analysis are tentative and will need more data in both groups to statistically analyse potential
left parietal effects with confidence along with calculating other necessary analyses such as
between-group ANOVA and topographical scalp maps. While neither hypothesis could be accepted
based on the information gathered, the study design worked well and could easily be repeated.
Future research replicating this study and combining it with other behavioural, ERP and fMRI results
with undoubtedly yield a better understanding of the underlying processes involved cognitive
ageing.
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Examination Number: 7879463
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Examination Number: 7879463
Gronlund, D., Carlson, C. & Tower, D. (2007). Episodic memory. In Durso, F. (Eds.), Handbook of
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46
Examination Number: 7879463
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47
Examination Number: 7879463
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55
Examination Number: 7879463
Appendix A – Consent forms for behavioural piloting and the ERP study
BEHAVIOURAL EXPERIMENT
Dear participant,
Please read the following information carefully.
Invitation To Take Part In A Research Study
You are being asked to take part in a research study in which we will examine differences between
younger and older adults in their ability to make decisions about and recognise pictures.
Time Commitments
This particular experiment will require up to 1 hour to complete (including reading of the
instructions).
Right To Withdraw
During the experiment you have the right to withdraw at any time; you are under no obligation to
continue if you do not wish to and it does not matter if you have already started the tasks. If you wish
to withdraw we will immediately stop the procedure and any data that you have produced up to that
moment will be destroyed.
Risks
There are no known risks for you in this study. This experiment conforms to the British
Psychological Society guidelines and ethical constraints for human experimental psychology.
Confidentially/Anonymity
The data we collect does not contain any personal information, and there is no way to link your name
to the data you provided.
Cost, Reimbursement And Compensation
You will be paid £6 for this experiment.
56
Examination Number: 7879463
For Further Information About This Research:
If there is anything not covered on this sheet which you would like to know, please do not hesitate to
contact us. We would be more than happy to discuss it further with you.
To participate or for more information, please
Lindsey Robb
Dr. Alexa Morcom
Psychology Department
University of Edinburgh
7 George Square
Edinburgh,
EH8 9JZ
email Lindsey Robb at s0678794@sms.ed.ac.uk or
phone on 07795576194.
Alternatively, if it is not possible to contact
Lindsey Robb, you can contact:
As an informed participant in this experiment, I understand that:
Dr. Alexa Morcom (Principal Investigator &
1.
2.
3.
supervisor)
My participation is voluntary and I may cease to take part in this experiment at any time,
without penalty.
Email: alexa.morcom@ed.ac.uk
I am aware of what my participation involves.
Tel:participation
0131 651 1907
There are no risks involved in the
of this study.
4.
This is a research project, not an assessment of me individually, and I will not be
identified in any results.
5.
All my questions about the study have been satisfactorily answered.
I have read and understood the above information and give consent to participate.
Participant’s Signature:___________________________
Date:__________
I have explained the above and answered any questions asked by the participant.
Researcher’s Signature:__________________________
Date:__________
Thank you for agreeing to participate in this study.
57
Examination Number: 7879463
EEG (Electroencephalogram) EXPERIMENT
Dear participant,
Please read the following information carefully.
Invitation To Take Part In A Research Study
You are being asked to take part in a research study in which we will examine differences between
younger and older adults in their ability to make decisions about and recognise pictures. EEG
(Electroencephalogram) reaction times and accuracy will be recorded during the experiment.
Time Commitments
This particular experiment will require around up to 2 hours to complete (including reading of the
instructions and cap preparation).
Right To Withdraw
During the experiment you have the right to withdraw at any time; you are under no obligation to
continue if you do not wish to and it does not matter if you have already started the tasks. If you wish
to withdraw we will immediately stop the procedure and any data that you have produced up to that
moment will be destroyed.
Risks
There are no known risks for you in this study. This experiment conforms to the British
Psychological Society guidelines and ethical constraints for human experimental psychology.
EEG Recording
The EEG recording involves you to wear an elastic electrode cap so we can record the
electrical activity of your brain. The gel applied to the electrodes means that you may want to
wash your hair afterwards: we have shower facilities for this. We will also ask you to sit as
still as possible and avoid eye movements during the EEG recording. These help us to record
good quality data.
Before we start EEG recording, you will have time to familiarise you with each procedure.
Confidentially/Anonymity
The data we collect does not contain any personal information, and there is no way to link your name
to the data you provided.
Cost, Reimbursement And Compensation
You will be paid £25 for this experiment.
58
Examination Number: 7879463
For Further Information About This Research:
If there is anything not covered on this sheet which you would like to know, please do not hesitate to
contact us. We would be more than happy to discuss it further with you.
To participate or for more information, please
Lindsey Robb
Dr. Alexa Morcom
Psychology Department
University of Edinburgh
7 George Square
Edinburgh,
EH8 9JZ
email Lindsey Robb at s0678794@sms.ed.ac.uk or
phone on 07795576194.
Alternatively, if it is not possible to contact
Lindsey Robb, you can contact:
As an informed participant in this experiment, I understand that:
Dr. Alexa Morcom (Principal Investigator &
1.
2.
3.
supervisor)
My participation is voluntary and I may cease to take part in this experiment at any time,
without penalty.
Email: alexa.morcom@ed.ac.uk
I am aware of what my participation involves.
Tel:participation
0131 651 1907
There are no risks involved in the
of this study.
4.
This is a research project, not an assessment of me individually, and I will not be
identified in any results.
5.
All my questions about the study have been satisfactorily answered.
I have read and understood the above information and give consent to participate.
Participant’s Signature:___________________________
Date:__________
I have explained the above and answered any questions asked by the participant.
Researcher’s Signature:__________________________
Date:__________
Thank you for agreeing to participate in this study.
59
Examination Number: 7879463
Appendix B – Basic Information form
EEG (Electroencephalogram) EXPERIMENT
Basic Information
Participant Number: ........................
Gender: Male ........................
Female ........................
Age: ........................
Handedness (for writing): ........................
Years of Education: ........................
Native Language: ........................
Normal Vision: Yes ........................
If not:
Correction:
No ........................
Glasses ........................ Contact lenses ........................
None
........................
Health questions
Please indicate by ticking the box if you have or have had any of the following:






Head injury requiring more than overnight hospital admission
Diabetes with complications
Brain surgery, or open heart and bypass surgery
Stroke, vascular or ischaemic incident, or major vascular surgery
A psychiatric illness requiring repeated treatment or hospital admission
(e.g. depression, schizophrenia)
Problems with drug or alcohol abuse
Are you currently

Experiencing any illness or undergoing any medical treatment that could potentially
interfere with your thinking or concentration?
If the answer to any of these is Yes, please include relevant details or tell the experimenter in
confidence:
........................ ........................ ........................ ........................ ........................ ........................
........................ ........................ ........................ ........................ ........................ ........................
........................ ........................ ........................ ........................ ........................ ........................
........................ ........................ ........................ ........................ ........................ ........................
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Examination Number: 7879463
Appendix C – Task information forms
Picture Decision Task
In this experiment, your first task will be to view pictures in the centre of the
screen. After viewing each picture, you will need to decide whether the realworld counterpart would fit inside a small box (this will be shown to you at the
start).
An example of the type of item you will be shown in the experiment is below:
[Note: This item will be in your practice session and will not be repeated in the
actual task.]
You will answer the question by pressing the right or the left button. The
experimenter will inform you about which button you will press will be the
“YES” and which button will be the “NO” answer.
Your main task is to answer as accurate as possible.
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There will be some practice trials in order to familiarise you with the
procedure. If you have any questions, please ask the experimenter now.
Both of the picture decision tasks will be recorded using EEG. To ensure good
quality data try to remain as relaxed as possible and reduce head
movements. It would also be beneficial to focus only on the centre of the
screen which is indicated by the black/red plus “+” sign or the pictures
shown.
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Examination Number: 7879463
Memory Task
In this second task, you will view a second set of pictures. After viewing each
picture you will need to decide whether the picture you saw was also in the
first task.
If the picture was exactly the same in the first task, you should answer “old”
indicating you have seen it before. This picture below was seen as an example
in the first information sheet. If it had been in the first task then you could
label it as “old”.
If the picture was similar to one shown in the first task (e.g. both were pictures
of puppies, however, they were different breeds), then you should answer
“similar” indicating they were different versions of the same item.
An example of this could be:
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[Note: If the first picture was of, for example, a lampshade and the other a
lightbulb this doesn’t mean they are in the same category. Only if they were
both lampshades or lightbulbs then they would be “similar”.]
If the picture is a new picture of which no “similar” items have been shown
before – then you should answer “new” indicating that you have not seen this
item or any similar items before.
For example:
Your main task is to answer as accurately as possible, but also try to respond as
quickly as you can whilst still being accurate. If you have any questions, please
ask the experimenter now.
As in the first task it is important to remain as relaxed as possible to obtain
the best EEG recording. Please focus as far as you can in the centre of the
screen as indicated by the plus “+” sign, as it’s important to move your eyes
around as little as possible, although you can blink normally.
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