Individual difference in criterion shifting
Supplemental Information for the manuscript:
Individual differences in shifting decision criterion:
A recognition memory study
Elissa M. Aminoff, David Clewett, Scott Freeman, Amy Frithsen, Christine Tipper,
Arianne Johnson, Scott T. Grafton, & Michael B. Miller
Department of Psychology, University of California, Santa Barbara
Institute for Collaborative Biotechnologies, University of California, Santa Barbara
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Individual difference in criterion shifting
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Supplemental Methods:
Participants
133 people were designated to participate in this study. 38 of the participants were not
used in the final analysis due to the following reasons: 8 did not pass MRI safety screening
measures; 4 were claustrophobic; 5 had a technical error in data collection; 20 participants
missed more than 40 trials (over 10% of the trials) in either the Words or the Faces test; 1 did
not follow task instructions.
Procedural Variations
The procedure and parameters detailed in the main text was used for a majority of our
participants (participants 31-133), however the first 30 participants had a slight variation of the
sequence of events and parameters of presentation. Participants 1-17 studied both the faces
and the words before going into the MRI. In this case the words were presented for 1 second
and the faces for 2 seconds, without an inter-stimulus interval. Participants 18-27 had the same
procedure as the first version except an inter-stimulus interval of 500ms was included.
Participants 28-30 studied both the faces and words in the MRI, however before both testing
sessions. As mentioned in the main text, method variations were always regressed out of the
analysis and did not have a direct effect on criterion shifting.
Reliance on cue information (RCI)
Two raters scored the free response questions with high consistency (Words r: .839;
Faces r: .838). The free response ratings between the two raters were then averaged together.
The final RCI score was an average of the averaged free response ratings and the ratings given
by the participant in the questionnaire (consistency Words r: .646; Faces r: .605).
Individual difference in criterion shifting
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Supplemental Results:
Optimal Criterion
In the Words test, only two participants reached and exceeded optimal criterion in the
High Probability condition, and five participants reached and exceeded optimal criterion in the
Low Probability condition. In the Faces task, three participants reached and exceeded optimal
criterion in the High Probability condition, and two participants reached and exceeded optimal
criterion in the Low Probability condition. No participants reached an optimal criterion shift in
both tasks.
Criterion Shift Range
Criterion shifting ranged from a minimal shift of -.4 for the Words, and -.29 for the Faces
to a maximum of 2.81 for the Words, and 2.19 for the Faces. The median criterion shift score
was .55 for the Words and .57 for the Faces. There was no relation between the participant’s
average criterion across conditions (i.e., their starting response bias) and criterion shifting
(Words: r = .006, n.s.; Faces: r = -.161, n.s.).
Criterion shifting across the duration of the experiment
In the results of this study we analyze criterion shift as a single value across the
duration of the whole experiment. However, it is possible that individuals shift criterion more (or
less) as the duration of the test increases. In assessing the reliance of cue information, each
participant was also explicitly asked whether they relied more or less on the cue as the test
progressed. A majority of the participants (45%) said they relied more on the cue as the test
went on, mostly due to fatigue and the increase of stimuli interference as the test went on. The
remaining participants were relatively split between saying they were consistent throughout the
test, and those that said they were less influenced (30%). We suggest these results support the
Individual difference in criterion shifting
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proposal that as task difficulty increases and memory declines, indicated by fatigue and stimuli
interference, a greater reliance on the cue information is found.
To further examine how criterion shifted across the duration of the experiment, we also
analyzed the performance data in sections to compare the first half compared to the second half
of the test. Although numerical higher in the second half, there was no significant differences
between criterion shifting in the first half compared to the second half of the test (Words: 1 st =
.596, 2nd = .661, p = .17; Faces: 1st = .567, 2nd = .652, p = .06). Since each participant
performed two sequential memory tests, we also compared the first half of the first test to the
second half of the second test. This comparison did not yield significant results either (1st =
.571, 2nd = .678, p = .12).
Additional reaction time analyses
Reaction times for the Faces recognition test were longer compared with the Words
recognition test (t(94) = 7.9, p < 10-11). There were no differences between different probability
conditions. Reaction time was a variable entered in the categorical regressions, but was not
found to have a significant relation to criterion shifting.
Reaction time was also compared in the trials in which the probability switched from
the previous trial compared with trials in which the probability stayed the same. Participants took
significantly longer to respond during the switch trials compared with the same trials (Words:
t(94) = 11.10, p < 10-18; Faces t(94) = 9.50, p < 10-14). We compared this difference in reaction
time of the switch versus same trials with the amount the participant shifted criterion, or relied
on the cue information. Overall, there was no significant relation between difference in RT and
criterion shifting or reliance on cue information. However, within the High Shifters there was a
significant relation between the amount of criterion shift and difference in reaction time of the
switch versus same trials (R2 = .213).
Individual difference in criterion shifting
Detailed Results from the Categorical Regressions
Category
Demographic
State of Mind
Cognitive Style
Mental Health
Personality
Behavioral
Variable
military rank
age
gender
education
handedness
scan time
arrival time
sleep
MSW
MSF
meals
caffeine
exercise
alcohol
smoking
anxiety
physical comfort
OSIQ-S
OSIQ-O
VVQ-W
VVQ-P
SBCSQ-vis
SBCSQ-verb
Need for Cognition
Paper Folding
Card Rotation
Vocabulary
Working Memory
BDI
PTSD
Concussion (lifetime)
Concussion (5yr)
PANAS shyness
PANAS fatigue
PANAS serenity
PANAS surprise
PANAS positive
PANAS negative
BIS
BAS reward
BAS drive
BAS fun seeking
EPQ-R psychoticism
EPQ-R lying
Big 5 Conscientiousness
Big 5 Agreeableness
Big 5 Openess
Extraversion
Neuroticism
RT High Prob.
RT Low Prob.
Words
0.347
0.028
0.082
0.080
0.034
0.205
-0.445
0.126
0.238
-0.250
-0.115
0.212
0.043
-0.003
-0.148
0.065
0.181
0.043
-0.057
0.077
-0.017
-0.091
-0.092
-0.081
0.360
-0.041
-0.003
-0.027
-0.136
0.300
-0.161
0.235
-0.111
0.137
-0.069
-0.075
0.185
-0.234
-0.027
-0.052
0.063
0.162
0.078
0.028
0.063
-0.132
-0.080
-0.064
-0.008
0.135
-0.208
Faces
0.247
0.251
-0.011
-0.024
0.047
0.088
-0.111
-0.130
-0.085
-0.061
-0.124
0.296
-0.029
-0.266
-0.056
-0.119
0.071
0.068
-0.130
0.278
0.055
-0.215
-0.067
-0.047
0.112
-0.121
-0.108
0.017
0.180
-0.213
0.100
-0.036
0.134
0.017
-0.083
0.089
0.045
-0.321
0.154
-0.176
0.032
0.461
-0.039
-0.055
0.105
-0.175
0.059
-0.057
0.027
-0.172
0.149
Table S1: Standardized Betas yielded from the categorical regressions analyses (bold
indicates p < .05).
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Individual difference in criterion shifting
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Correlations between variables
Table S2: Correlations across the different variables entered in the equation. Bolded
values indicate p < .05, uncorrected.
Other variables significantly related to criterion shifting, but mostly through shared
variance: Sleep had a negative effect on criterion shift (Words Beta: -.235, p < .022), but this
effect was largely mediated by correlated variables: procedure variations and rank. Verbal
tendencies also consistently positively effected criterion shifting (nearly significant for Faces,
Beta: .174, p < .052), although this measure was highly mediated by other characteristics,
namely rank.
Individual difference in criterion shifting
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Military Rank and Criterion Shifting
Because the regressions included non-military participants entered as 0 for military rank,
we also ran a regression with only the military participants and included other military variables
besides rank (e.g., time in army, length of deployment, months since last deployment, and
combat experience). This regression was run with the procedural, memory, and RCI variables
entered first, as in the categorical regressions run in step one. The purpose of this regression
was to investigate whether the relation between rank and criterion shift held up with only military
participants, and to try to reveal what aspects of military experience was the driving factor in the
original relation found between rank and criterion shifting. In these regressions, rank still had a
similar effect on criterion shifting, and the strongest effect compared to all other military
variables, however it was only significant in the Words dataset (Beta: .349, p < .013) (see Table
S3). None of the other military variables were significantly related to criterion shifting. This
suggests that there is something inherent about the leadership role and advancement in rank
that relates to criterion shifting for Words that is independent from other military experience. For
the Faces dataset, rank still had a strong effect (Beta: .228), but was mediated by other factors
such as time in army.
Table S3: Standardized Beta values yielded from the military regression. N = 68. Bold
indicates p < .05.