Cognitive Systems
Tutorial 1 / October 22, 2012
Prof. Dr. Sven Bertel / JP Usability
Today’s topics
●  Organizational issues & literature
●  Introduction into cognition
●  Discussion of readings for today:
●  Topical paper: Introduction to computational
cognitive modeling [Sun, 2008]
●  Application paper: Effects of Compressed
Online Foveated Video on Viewing Behavior
and Subjective Quality [Nyström &
Holmqvist, 2010]
(Useful slides relating to background for second
paper are collected below.)
Organizational issues
Lectures & Tutorials: Times & Locations
●  14 lectures + 7 tutorials
●  Lectures mostly on Wednesdays,
3x on Tuesdays
●  Tutorials always on Tuesdays
●  Tuesdays: 1.30-3pm
Seminarraum 014, Bauhausstraße 11
●  Wednesdays: 9.15-10.45am,
Seminarraum 102, Marienstraße 7B
This is new. Concept.
●  Mix of organization by topic and
organization by application/domain
●  Putting techniques and methods to use later
will be within application contexts, problemcentered
●  Rather open format, more discussions, feedback; hands-on, group-based activities
●  Regular reading assignments, likely short
position papers
This is new. Concept.
●  Example: first reading assignment
●  Topical paper: Introduction to computational
cognitive modeling [Sun, 2008]
●  Application paper: Effects of Compressed Online
Foveated Video on Viewing Behavior and
Subjective Quality [Nyström & Holmqvist, 2010]
●  Papers, slides, assignments, other resources
to be made available online on course page at
www.uni-weimar.de/usability
●  login: q0gnit1oN
passw: rul3Z
This is new. Concept.
●  Regular assignments in tutorials
●  Finals (oral or/and written, tba).
●  You will need to pass the assignments to take
the final.
●  Exact conditions to be presented during first
tutorial.
●  Feedback most welcome. Suggestions,
comments, lamentations, praise. You name it.
(The more constructive, the better, of course.)
Grading scheme
Of overall grade:
●  60%: final exam
●  Likely oral
●  Potentially in groups
●  30%: tutorials
●  Hand-in homework (first one on ACT-R to be
announced at, or before, second tutorial)
○  Written part
○  Presentation in class or separately
●  In-class work
Grading scheme
●  10% related to reading assignments:
Selected papers
●  Start from selected paper(s) on methods,
techniques, projects, systems, …
from there: own research on related work
●  Concise presentation in class, as groups
●  Concise position papers
THE calendar
TUE
WED
10/17 L1
10/23 T1
10/24 L2
10/30 L3
10/31 ---
11/06 T2
11/07 L4
11/13 ---
11/14 L5
11/20 T3
11/21 L6
11/27 L7
11/28 ---
12/04 L8
12/05 ---
12/11 T4
12/12 L9
L – lecture, T – tutorial
THE calendar
TUE
WED
12/18 ---
12/19 L10
01/08 T5
01/09 L11
01/15 ---
01/16 L12
01/22 T6
01/23 L13
01/29 T7
01/30 L14
L – lecture, T – tutorial
Basics: useful textbooks
●  Perception
●  Jeremy Wolfe et al. (2012).
Sensation and Perception, 3rd ed. Sinauer
Associates, Sunderland, MA, USA
●  E. Bruce Goldstein (2010).
Sensation and Perception, 8th ed.
Wadsworth.
* At the university library.
Basics: useful textbooks
●  Cognition
●  John R. Anderson (2010).
Cognitive Psychology and Its
Implications, 7th Edition.
Worth Publishers, New York. *
(à contains various references
to ACT-R)
* At the university library.
Specific literature
To be announced as we move along.
Cognition
perception & attention
Learned Associations
Traffic signs: Learned meanings!
Just as: Learned cultural associations
●
●
●
●
red - danger, stop, delete
green - go, environmentally friendly
white - pure, clean, honest
black - serious, heavy, death
Associations may be different for different
cultures
Is this designed well?
●
●
●
●
●
●
●
Correct Size
Correct Shape
Correct Location?
Correct Weight
Correct Color
Correct Material
But…
à  Ability to (re-) interpret meaning and act
on interpretation!
Now:
●  What is cognition?
●  What are users good and bad at?
●  sensory organs
(afferent)
●  thinking organs
+ memory
●  effectors (efferent)
Some of the following slides (Intro to CogSci) are partly based on material of previous
semesters of http://cosy.informatik.uni-bremen.de/category/teaching/cognitive-systems
Cognitive System
Cognition:
What goes on in the mind?
Experiential cognition
(comes with practice,
repeating e.g. driving a
car) vs. reflective
cognition (thinking and
reflecting, e.g. deciding
on what car to buy)
Cognition (Definition I)
Cognition: the mental processes used in
perception, memory, communication, thinking,
reasoning, remembering, judgment and
understanding.
adapted from Merriam-Webster dicitonary & Psychology: A ConnecText, byTerry Pettijohn
Cognition (Definition II)
“Cognition” refers to the principles underlying
intelligence and intelligent systems with
particular reference to intelligent behavior as
computation.
HA Simon & CA Kaplan, Foundations of Cognitive Science, in MI
Posner, ed, Foundations of Cognitive Science, MIT Press 1991.
(Sun, 2008; p.3)
Cognitive System:
Computation Metaphor
Input
Memory
Reasoning
Unit
Processor
Output
Beyond the Cognitive System
Environment
●  Source of input
Cognitive
system
●  E.g. ambient temperature, speech
generated by another cognitive system, book, …
●  Manipulation of environment
●  E.g. store food for the winter, make notes, …
●  Communication with other cognitive systems
●  E.g. speak, put up traffic signs, …
●  External memories
●  E.g. notes, book, (spatial) structure of the
environment, …
Likely, no one remembers the detailed layout of Times Square
(à complexity, visual clutter, …)
One can still recognize it, navigate on it etc.
(à use of information encoded in external structure / representations).
29
Cognition & Usability
Why do we need to look at cognition?
●  Better understanding & modeling of human
performance at tasks
●  Limits (What can + can’t a user do?)
Limits
For example, there exist various limits to human
memory.
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Cognition & Usability
Why do we need to look at cognition?
●  Better understanding & modeling of human
performance at tasks
●  Limits (What can + can’t a user do?)
●  Specific properties (e.g. of a certain user / user group)
Does Seeing One’s Hand Help?
Example discussed during
the first lecture:
Different users may have
different cognitive
properties
Back of hand
Palm
Camera shows
Keehner, M. (2008). Conflicting Cues from Vision and Touch can Impair Spatial
Task Performance: Speculations on the Role of Spatial Ability in Reconciling
Frames of Reference. In Spatial Cognition VI. LNCS 5248, Springer.
Image: http://www.colorectalhalgroup.com.au/images/handport_drawing.gif
Hand Assisted Minimally Invasive Surgery
Cognition & Usability
Why do we need to look at cognition?
●  Better understanding & modeling of human
performance at tasks
●  Limits (What can + can’t a user do?)
●  Specific properties (e.g. of a certain user / user group)
●  Needs (How to support cognition for better performance?)
Does Seeing One’s Hand Help?
Example discussed during
the first lecture
Different users may have
different cognitive properties
which may lead to different
needs (e.g. in H-C interaction)
Back of hand
Palm
Camera shows
Keehner, M. (2008). Conflicting Cues from Vision and Touch can Impair Spatial
Task Performance: Speculations on the Role of Spatial Ability in Reconciling
Frames of Reference. In Spatial Cognition VI. LNCS 5248, Springer.
Image: http://www.colorectalhalgroup.com.au/images/handport_drawing.gif
Hand Assisted Minimally Invasive Surgery
Cognition & Usability
Why do we need to look at cognition?
●  Better understanding & modeling of human
performance at tasks
●  Limits (What can + can’t a user do?)
●  Specific properties (e.g. of a certain user / user group)
●  Needs (How to support cognition for better performance?)
●  Build better tools
●  Learn from how humans function
Computational models of cognitive
processes for use in tools
Example: Cognitive simulation of ship navigation by
navigator and helmsman for risk assessment
K. Itoh, T. Yamaguchi, J. P. Hansen and F. R.
Nielsen. Risk Analysis of Ship Navigation by
Use of Cognitive Simulation. Cognition,
Technology & Work (2001) 3:4–21
Cognition & Usability
Why do we need to look at cognition?
●  Better understanding & modeling of human
performance at tasks
●  Limits (What can + can’t a user do?)
●  Specific properties (e.g. of a certain user / user group)
●  Needs (How to support cognition for better performance?)
●  Build better tools
●  Learn from how humans function
●  Better interaction between humans and tools
●  Tailor interaction to cognitive processes of users
●  Also when tools take over some cognitive functions
Tailor interaction to cognitive
processes of users
●  E.g. intelligent tutor systems
Adapt tutoring to
student’s learning
progress
(CMU’s LISP tutor)
LISP, geometry, genetics, physics, …
●  Shared human-computer control
●  …
Andes physics tutor
Bremen smart wheelchair Rolland
Images: Anderson et al. (1989). Skill Acquisition and the LISP tutor. Cognitive Science, 13, 467-505. / http://www.cs.cmu.edu/~cprose/pslc-slides/
StudyingandachievingrobustlearningwithPSLCResources.ppt / www.ensta-paristech.fr/~stulp/.../kriegbrueckner08adaptation.pdf
Development of HumanMachine Systems
Cf. Hollnagel, E. & Cacciabue, P. C. (1999). Cognition, technology and work: An introduction. Cognition, Technology and Work, 1(1):1–6.
Manual Control
●  Display of simple physical measurements
●  E.g. pressures, temperatures
●  Often: One sensor – one indicator
●  Local control
●  Manipulation of single components (e.g. valves, switches)
●  Machine primarily as amplifier of human physical
strength and precision
●  Humans effectively just another piece of
equipment to support machine functions. Tasks:
●  Mainly observation, detection, manual operation
●  Occasionally: process tuning or fault management
Cf. Hollnagel, E. & Cacciabue, P. C. (1999). Cognition, technology and work: An introduction. Cognition, Technology and Work, 1(1):1–6.
Images from http://farm3.static.flickr.com/2329/2293980977_730f3b3fb3.jpg, http://www.oldbeacon.com/beacon
/images/inductor_big-4.jpg,
Development of HumanMachine Systems
Cf. Hollnagel, E. & Cacciabue, P. C. (1999). Cognition, technology and work: An introduction. Cognition, Technology and Work, 1(1):1–6.
Supervisory Control
●  Technological developments increased
machine complexity & demands on operators
●  Precision, speed and sustained attention exceeded
human capacity
à  Solution: automation took over manual control
●  Operators as supervisors who step in when
things go wrong
●  Tasks:
●  State recognition, fault finding,
scheduling of tasks during e.g. start-up
and shutdown sequences, process
tuning, etc.
Cf. Hollnagel, E. & Cacciabue, P. C. (1999). Cognition, technology and work: An introduction.
Cognition, Technology and Work, 1(1):1–6. Image: http://www.ebreaker.de/images/015-rollad1401.jpg / http://www.ornl.gov/info/ornlreview/v38_1_05/images/a11_controls_full.jpg
Control room at a nuclear
power plant
(USA, Tennessee Valley Authority)
Development of HumanMachine Systems
Cf. Hollnagel, E. & Cacciabue, P. C. (1999). Cognition, technology and work: An introduction. Cognition, Technology and Work, 1(1):1–6.
Cf. Hollnagel, E. & Cacciabue, P. C. (1999). Cognition,
technology and work: An introduction. Cognition,
Technology and Work, 1(1):1–6. / Image + caption:
http://www.carbibles.com/brake_bible_pg2.html
Cognitive Control
●  Necessary with yet increasing complexity of systems
and machines
●  More extensive automation has removed operator
even further from the actual process
à Focus on cognitive aspects of joint human-machine
system
A (relatively easy) example of shared control in
human-machine interaction: Volvo's collision
warning system (CWS) constantly monitors
speed and uses a 15° forward field of view radar
to determine the distance to any object in front. If
the distance begins to shrink but you don't slow
down, the system sounds a buzzer and flashes a
bright red light in a heads-up display to alert
you. The brake pads are automatically placed
against the discs and when the driver finally
does use the brakes, the system monitors the
pedal pressure. If the pressure is determined to
be too light, the braking power is amplified by
the system.
Cognitive Control
●  Today: Work is mediated by information
technology and allocated between humans and
machines
●  Usually according to the nature of the process (and its
physical implementation) rather than considerations of
joint human-machine system functioning
●  Creates problems for functioning of joint humanmachine system à not at optimum
à  Need to provide explicit design for the humanmachine system, e.g. with respect to
performance envelopes
à  Study cognition! (natural + artificial)
Cf. Hollnagel, E. & Cacciabue, P. C. (1999). Cognition, technology and work: An introduction. Cognition, Technology and Work, 1(1):1–6.
What is Cognitive Science?
The critical aspect of Cognitive Science is
the search for understanding of cognition,
be it real or abstract, human or machine.
Donald A. Norman, What is cognitive science?, D. Norman,
ed, Perspectives on cognitive science, Ablex, NJ 1981.
Domain of Cognitive Science
Examples:
real
abstract
human
wayfinding
in a city
imagining your
next vacations
machine
robot avoiding
obstacles
computer
planning a trip
Disciplines of Cognitive Science
real
abstract
human
psychology
anthropology
neurosciences
linguistics
philosophy
logics
machine
artificial intelligence
cognitive robotics
informatics
mathematics
Approaches to Cognitive Science
real
abstract
human
empirical studies
biological
models
machine
synthetic
constructions
theoretical
process models
Natural vs. Artificial Cognitive Systems
calculating
playing games
speaking
planning
perceiving
understanding
arguing
learning
recovery
natural
weak
weak/strong
strong
pretty good
very strong
very strong
strong
strong
very strong
artificial
strong
strong/weak
improving
quite good
specialized
weak
weak
improving
weak
Some Cognitive Abilities (1)
●  Ability to detect and interpret sensory stimuli
Example:
On the following slide you will briefly see a
number of colored geometric objects. Detect as
fast as possible how many blue circles there are.
ready?
your
answer?
(5)
Cognitive Abilities (2)
●  Ability to detect and interpret sensory
stimuli
●  Tendency to focus on certain sensory
stimuli and to disregard others
Example:
Was there a yellow hexagon among the colored
geometric objects?
your
answer?
(no)
●  …
●  Tendency to focus on certain sensory stimuli
and to disregard others
●  Ability to extract parts
of complex events and
to integrate them
into a schema that
gives meaning to
the episode
Video: https://www.youtube.com/watch?v=r8DydFeC9BA
Cognitive Abilities (3)
Cognitive Abilities (3)
●  …
●  Tendency to focus on certain sensory stimuli
and to disregard others
●  Ability to extract parts of complex events and to
integrate them into a schema that gives
meaning to the episode
●  Detailed knowledge of the physical
characteristics of the environment
(by Mary Hegarty)
Tying shoelaces
How many windows are in your
home?
Cognitive Abilities (4)
●  …
●  Ability to extract parts of complex events
and to integrate them into a schema that
gives meaning to the episode
●  Ability to extract meaning from letters
and words
Examples …
C T
Jim observed the hunter
with the binoculars
He was just about to
pull the trigger
He was looking
for the deer.
http://www.owlnet.rice.edu/~psyc351/Images/ContextEffects.jpg
Examples / Context effects
Cognitive Abilities (5)
●  …
●  Ability to extract parts of complex events and to
integrate them into a schema that gives
meaning to the episode
●  Ability to extract meaning from letters and words
●  Capacity to retain explicit knowledge and to
integrate it into an ongoing sequence
Example …
This slide shows all circles
of the picture
you saw a while ago,
except for the blue ones.
Give me the number of circles
in the original figure.
Cognitive Abilities (6)
●  …
●  Ability to extract meaning from letters
and words
●  Capacity to retain explicit knowledge and
to integrate it into an ongoing sequence
●  Ability to form an image of a
“cognitive map”
For example …
Cognitive maps (Kosslyn, Ball, & Reiser, 1978)
Cognitive maps often preserve
some relationships found in the space
which they represent.
Which city is further south
Santiago de Chile or New York?
Which city is further west
Santiago de Chile or New York?
73°56′19″W
70°39.02′W
Mental maps are often not veridical.
73
Cognitive Abilities (7)
●  …
●  Capacity to retain explicit knowledge and
to integrate it into an ongoing sequence
●  Ability to form an image of a “cognitive
map”
●  Ability to solve a problem
For example …
§  Three missionaries and three
cannibals want to cross a
river from side A to side B.
§  They have a boat that
holds no more than two
persons at a time.
§  The life of the missionaries is
endangered when the cannibals
outnumber the missionaries at any
location.
How can the six missionaries safely
cross the river?
Image: http://thiscircularparade.com/wp-content/uploads/2012/01/1aIllustrated_world-108_edited-1.jpg
Missionaries and Cannibals Problem
Cognitive Abilities (8)
●  …
●  Ability to form an image of a “cognitive
map”
●  Ability to solve a problem
●  Translation of a high-level instruction
into a complex motor response
For example …
“Quickly run up the stairs, please.”
Cognitive Abilities (9)
●  …
●  Ability to solve a problem
●  Translation of a high-level instruction into
a complex motor response
●  Ability to recall quickly from long-term
memory specific information that is
immediately applicable to the present
situation
For example …
What are your parents’ names
and dates of birth? …
Cognitive Abilities (10)
●  …
●  Translation of a high-level instruction into a
complex motor response
●  Ability to recall quickly from long-term memory
specific information that is immediately
applicable to the present situation
●  Ability to translate visual events into spoken
language
For example …
Describe what happened in the
movie you saw a couple of
minutes ago …
Cognitive Abilities (11)
●  …
●  Ability to recall quickly from long-term memory
specific information that is immediately
applicable to the present situation
●  Ability to translate visual events into spoken
language
●  Tendency to store linguistic information in a
general form
For example …
Can you recall the last task regarding
the colored objects I presented?
The task was:
“Give me the number of circles in the
original figure.”
Cognitive Abilities (12)
●  …
●  Ability to translate visual events into
spoken language
●  Inability to perform perfectly
Inability to Perform Perfectly
●  In a complex open world it is impossible
to guarantee perfect solutions
●  We need ways to discover imperfections
●  We need ways to recover from imperfections
●  Such “imperfections” are part of the
operating principles of cognition!
Core cognitive aspects
●
●
●
●
●
Perception and recognition
Attention
Memory
Reading, speaking and listening
Problem-solving, planning, reasoning
and decision-making, learning
In relation to Nyström & Holmqvist, 2010:
Resolution of the human visual system
is differs across visual field. High acuity
in foveal vision, low acuity in peripheral
vision.
no.of receptors per square mm
Density of Rods &
Cones in the Visual Field
temporal
fovea
Angle (degrees)
nasal
From Coren, Porac, Ward., Sensation & Perception
Rods & Cones
Image: http://eyetracking.me/wp-content/uploads/2009/04/field_of_vision.png
Foveal, parafoveal, peripheral vision
Figure 2.10 The “rule of thumb”
Image: Yang, S. & McConkie, G. W. (2005). New directions in theories of eye
movement control during reading. In G. Underwood (ed.), Cognitive
Processes in Eye Guidance, (pp. 105–130). New York: Oxford University Press.
Repeat: Field of View
Discussion of reading for today:
In relation to Nyström & Holmqvist, 2010:
Eye movements
Targeting eye movements:
●  Smooth pursuit
●  Saccade
●  Fixation
Other:
●  Vergence: The two eyes move in opposite
directions, as when both eyes turn towards the nose
●  Reflexive: Automatic and involuntary eye
movements
Image / content: Wolfe et al.
Types of Eye Movements
Targeting eye movements:
●  Smooth pursuit: The eyes smoothly follow a moving
target
Video: The University of Utah 2001 under a Creative Commons Attribution-NonCommericalShareAlike 2.5 License // http://www.youtube.com/watch?v=sKrvQgoR2uk
Types of Eye Movements
Targeting eye movements:
●  Saccade: A rapid movement of the eyes that
changes fixation from one object or location to
another
Video: The University of Utah 2001 under a Creative Commons Attribution-NonCommericalShareAlike 2.5 License // http://www.youtube.com/watch?v=sKrvQgoR2uk
Types of Eye Movements
Types of Eye Movements
Targeting eye movements:
●  Saccade: A rapid movement of the eyes that
changes fixation from one object or location to
another
○  Saccadic amplitude: angular distance travelled
○  Fastest movement of the human body
○  Ballistic: top velocity proportional to amplitude
(for all but very large amplitudes)
○  Amplitudes > ca. 20° usually with head movements,
but much higher amplitudes possible
Saccadic suppression: The reduction of
visual sensitivity that occurs when we make
saccadic eye movements
●  Saccadic suppression eliminates the smear
from retinal image motion during an eye
movement
à When do we see?
Image / content: Wolfe et al.
Eye Movements
Types of Eye Movements
Targeting eye movements:
●  Fixational eye movement:
○
○
○
○
Rather stationary period,
between saccades,
nearly all visual processing occurs during fixations
common duration depends on various factors
(task, level of mental processing, stimulus, …)
Saccadic suppression: The reduction of
visual sensitivity that occurs when we make
saccadic eye movements
●  Saccadic suppression eliminates the smear
from retinal image motion during an eye
movement
à When do we see?
Image / content: Wolfe et al.
Eye Movements
Image: http://1.1.1.3/bmi/www.learning-systems.ch/multimedia/fix.gif //
http://upload.wikimedia.org/wikipedia/commons/e/ef/Reading_Fixations_Saccades.jpg
Reading
text
Image: p. 205, Eyetracking Web Usability by Jakob Nielsen and Kara Pernice.
Sequence of gaze positions
Eye movements
●  Reading off of information: sequential, piecemeal,
selective
●  Sequence may be influenced by
○  Structure, content, visual features, … (external)
○  Reasoning, representations, memory, task, …(mental)
Videos by http://www.eyeseecam.com/
Seeing through somebody else’s
eye movements
EyeSeeCam
Videos by http://www.eyeseecam.com/
Seeing through somebody else’s
eye movements
EyeSeeCam
In relation to Nyström & Holmqvist, 2010:
Eye movements depend on task.
Image: Repin: The unexpected visitor. Source: Wikimedia
Eye movements during different tasks
(Yarbus, 1967)
Eye movements during different tasks
Context
●  Also the other way around: analysis of visual
inspection sequence may provide information
on involved
●  Mental processes
●  Mental representations
Different sequences of inspection under different tasks
http://www.useit.com/alertbox/fancy-formatting.html
One Question to Ask:
Do Users Look at the Relevant Parts?
Holsanova, J., Holmqvist, K. & Holmberg, N. (2008): Reading information graphics:
The Role of Spatial Proximity and Dual Attentional Guidance. Applied Cognitive
Psychology (2008). Published online in Wiley InterScience
(www.interscience.wiley.com) DOI: 10.1002/acp.1525.
Multimedia Aspects: Integration of Text & Images
Eye movements may depend on used representation
formats (here: text/diagrams) and their placement.
In relation to Nyström & Holmqvist, 2010:
Eye movements differ between people:
E.g. due to levels of expertise.
(Remember that N&H’s approach depends
on similarity of (first) eye movements
between people.)
  
 Image: Yang, S. & McConkie, G. W. (2005). New directions in theories of eye
movement control during reading. In G. Underwood (ed.), Cognitive
Processes in Eye Guidance, (pp. 105–130). New York: Oxford University Press.
Eye Movements & visual search
Fig. 5. The scan paths of two different observers, when reading the set of CT
images shown in Fig. 4. Top row: result for a consultant radiologist who
specialises in lung imaging. Middle and bottom rows: results for a novice
observer before and after training.
Image: Yang, S. & McConkie, G. W. (2005). New directions in theories of eye
movement control during reading. In G. Underwood (ed.), Cognitive
Processes in Eye Guidance, (pp. 105–130). New York: Oxford University Press.
Differences in visual search patterns of expert and novice radiologists.
In relation to Nyström & Holmqvist, 2010:
Eye movements are influenced by
properties of inspected scene / image
etc. (such as changes in contrast, shapes,
movements, etc. Cf. feature detectors in
early vision (area V1)). At least, when first
viewing a scene (cf. first part of study of
Nyström & Holmqvist).
Following example of computation of
saliency map from Itti & Koch, 2001.
Image: http://kybele.psych.cornell.edu/~edelman/Psych-4320/IttiKoch01-fig1.jpg
In relation to Nyström & Holmqvist, 2010:
Focus of eye movements (specifically, of
fixations, a type of eye movements) does
not need to be co-located with focus of
attention.
Good demonstration of this via the Posner
cueing paradigm.
Image: Wolfe et al.
Posner Cueing Paradigm
Posner Cueing Paradigm
●  Cue?
A stimulus that might indicate where (or what) a
subsequent stimulus may be.
Image: Wolfe et al.
○  Valid
○  Invalid
○  Uninformative
Peripheral cue
Image: Wolfe et al.
Posner Cueing Paradigm
Symbolic cue
Image: Wolfe et al.
Posner Cueing Paradigm
Image: Goldstein, 8th edition
Procedure for (a) the valid task and (b) the invalid task in Posner et al.’s
(1978) precueing experiment. (c) The results of the experiment: average
reaction time was 245 ms for valid trials but was 305 ms for invalid trials.
Image: Wolfe et al.
Posner Cueing Paradigm
Attention! Attention.
●  Attention?
Any of the very large set of selective processes in
the brain. Impossible for nervous system to handle
all inputs at once à mechanisms that restrict
processing to a subset
●  Selective attention?
The form of attention involved when processing is
restricted to a subset of the possible stimuli.
On
●  Locations
●  Features,
●  ...
Image: http://img.labnol.org/di/images/SpotLightf_178D/mousecursorspotlight.gif
Spotlight metaphor for how visual
attention gets allocated
Image: Goldstein
Spotlight metapher of attention:
Sequential scene perception
Focus of attention falls within foveal vision.
Image: http://eyetracking.me/wp-content/uploads/2009/04/field_of_vision.png
Overt attention
Focus of attention elsewhere in visual field
(does not fall within foveal vision).
Image: http://eyetracking.me/wp-content/uploads/2009/04/field_of_vision.png
Covert attention