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Chapter 11

PSYB57H3 Chapter Notes - Chapter 11: Necker Cube, False Alarms (1936 Film)

Course Code
George Cree

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Chapter 11 Visual Knowledge 339
Visual Imagery
Introspections about Images
- Mental images studied by psychologists to show systematic data about imagery
Francis Galton: asked people to describe their images and rate them for vividness
Introspect/look within and report their own mental contents
Self-report data fit well with common sense: Participants reported that they could “inspect” their images as
much as they would inspect a picture, could “read off” from image details of colour and texture
Mode of representation that is picture-like
Participants differed widely from each other (i.e. some were rich in detail while others were very sketchy)
Do individuals differ in the nature of mental imagery?
Chronometric Studies of Imagery
- Imagery researchers have been interested w/ what people do with their images read information off them or
manipulate them in some way (examine how accurate or how fast people are in their responses, and w/
appropriate comparisons to measure as basis for
testing hypotheses)
- Chronometric/time measure studies give more
accurate portrait of mental imagery
i.e. let people know what information are used in
mental image and what sorts are not, and see
how “picturelike” mental images are
i.e. writing a paragraph of a cat and not including
facts that cats have heads etc.
Pattern of what information is included and what
info is prominent depends on the mode of
presentation (i.e. description vs. depiction)
-Study w/ Kosslyn (1976)participants were asked to
form a series of mental images and answer yes/no
questions about each. They were asked to form a
mental image of cat and asked “Does the cat have a
head? Does the cat have claws?” Participants asked quickly and responses to head question were quicker than
those to claws question. Information quickly available in the image follows the rules for pictures not paragraph
Another group were asked to think about cats, asked same question, but gave quicker responses to claws reverse
- Another example” memorize locations of various landmarks: well, straw hat etc. Made participants have map
memorized by asking them to draw a replica of the map form memory, then main experiment
- When scanning across a mental image, there is a clear relationship b/w “travel time” and “travel distance”
travelling a greater distance requires more time
Mental Rotation
- Transformation of mental images
- Experiments w/ Shepard, Cooper and Metzler: Participants asked to decide whether 2 different shapes or 1 from
2 different perspectives
Is it possible to rotate the form so that is will end up looking just like the form on the right?

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- Mental rotation task: Participants seems to imagine one of the forms
rotating into alignment with the other. Once the forms are oriented in
the same way, participants can make their judgment
- Imagined movement resembles actual movement: The farther one has to
imagine a form rotation, the longer the evaluation takes
- Can be used to answer many questions about imagery (i.e. p 382-83)
- People have no trouble w/ mental rotation in depth (accuracy levels ~95%)
- Clear relationship b/w angle of rotation and response times, and speed of
rotation seems similar for both
Avoiding Concerns about Demand Character
- Problems with experiment participants know that movement through
world takes time and that moving a longer distance takes more time
- Participants are not imagining rotations or scanning across an image at all
might be thinking “the experimenter just asked me to scan a long way
- Why would they act this way? Participants want to be elpful they are
sensitive to demand character of experiment cues that might signal how they are “supposed to “ behave in
that situation
- Scanning and rotation data are as they are because of how images represent spatial layout experimenters ask
participants to make judgments about spatial layout but have taken care never mention
Interactions Between Imagery and Perception
- Important parallels b/w visual images and
actual visual stimuli if images are so much
like pictures, what is the relation b/w
imaging and perceiving?
- Segel and Fusella (1970-71): Participants
asked to detect very faint signals (dim
visuals or soft tones). On each trial, the
participants indicate whether signal was
presented or not
2 conditions: Either while forming
visual image before “mind’s eye” or
while forming auditory image before
their “mind’s ear”
If processes//structures occupied w/
imaging, they are not available for
perceiving and vice versa
- Can visualizing a stimulus “pave the way” for perception?
Farah (1985) had participants visualize a form (H/T), either an H/T was shown at low contrast, perception was
facilitated if participants had just been visualizing the target form Visualizing H or T made it easier to perceive H
- Visualizing and perceiving draw similar mechanisms
- Neuroimaging shows that visual perception relies on tissue in occipital cortex when someone examines
visual stimulus before their mind’s eye
Area V1 and V2 involved in earliest stages of visual perception (flow=level features of input)
Amount of brain tissue activation increases as people imagine larger and larger objects
Area MT/MST sensitive to motion in ordinary visual perception and imaging movement pattern
- Brain areas active in perceiving faces are active when imaging faces
- Brain damage: Patients w/ disrupted ability to perceive colour lose ability to imagine scenes in colour, patients
who’ve lost ability to perceive fine detail lose ability to visualize fine detail
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