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Chapter 11

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


Department
Psychology
Course Code
PSYB57H3
Professor
George Cree
Chapter
11

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Chapter 11 visual knowledge
People describe their thoughts in a variety of ways: 1) in words, 2) in an abstract form a
sequence of ideas that lacks any concrete form, and 3) in a sequence of pictures, or
sounds, or other sensory impressions
Visual Imagery
How many windows are there in your house? You call to mind a “map” of your house
and count the windows by inspecting this map
Many people even trace the map in the air by moving their finger around, following the
imagined map‟s contours
Introspection About Images
Among the earliest imagery researcher was Francis Galton he asked various people to
describe their images and to rate them for vividness
He asked subjects to introspect (or “look within”) and to report the mental contents
Subjects reported that they could “inspect” their images much as they would inspect a
picture
In their images, scenes were represented as if viewed from a certain position & a certain
distance
They also reported that they could “read off” from the image details of colour & texture;
this is consistent with the informal way of describing mental images as “pictures in the
head”, to be inspected with the “mind‟s eye”
Many described images of photographic clarity and rich in detail; other reported very
sketchy images or no images at all they were able to think about the scenes or objects,
but cannot “see” them
Do individuals differ in the nature of their mental imagery?
These self-reports shouldn‟t be taken at face value
Perhaps all of his subjects had the same imagery skill, but some were cautious in how
they chose to describe their imagery, while others were more extravagant
Galton‟s data might reveal differences in how people talk about their imagery rather than
differences in the imagery per se
Chronometric Studies of Imagery
To gain more objective data, experimenters ask people to do something with their images
to read information off of them or to manipulate them in some way
Chronometric study: “time-measuring” study; a study that measures how accurate and
how fast people are in their responses
Chronometric studies gives us an accurate portrait of mental imagery than a self-report
Chronometric studies allow us to ask what sorts of information are prominent in a mental
image and what sorts are not; we can then use these evaluations as a basis for asking how
“picture-like” mental images are
What information is included & what information is prominent, depends on the mode of
the presentation

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1) Description the features that are prominent will be those that are distinctive and
strongly associated with the object
o When asked to write a description of a cat, we are likely to mention the
distinctive features of cats whiskers, claws, and so on
o We will not include the fact that cats have heads (because it is too obvious)
2) Depiction distinctiveness and association won‟t matter; size and position will
determine what is prominent and what is not
o When asked to draw sketch of cat, the cat‟s head would be prominent because
the head is relatively large and up front
o Claws and whispers might be less salient, because these features are small and
would not take up much space in the drawing
Self-reports about imagery indicate a picture-like (depiction) representation
People have the option of thinking about cats via imagery and also the option of thinking
about cats without imagery; as the mode of representation changes, so does the pattern of
information availability
This experiment is an example of an image-scanning procedure
o Subjects first memorized this map, including the various
landmarks (the hut, the well, the patch of grass, and so on)
o Subjects were asked to form an image of the island, and to
point their “mind‟s eye” at a specific landmark (the hut)
o Another landmark (the well) was then mentioned
o Subjects were asked to imagine a black speck moving in a
straight line from the 1st landmark to the 2nd
o When the speck “reached” the 2nd landmark, subjects
pressing a button, stopping a clock
o This provides a measure of how long it takes to scan from
the hut to the well
o “Scanning times” for each of the various pairs of
landmarks were recorded
There is a clear relationship between “travel time” and “travel
distance”

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Subjects scan across their images at a constant rate, so that doubling the scanning
“distance” doubles the time required for the scan, and tripling the distance triples the time
required
Similar results are obtained if subjects are given a task that requires them to “zoom in” on
their images or a task that requires them to “zoom out”; response times are directly
proportional to the amount of zoom required
Images preserve the spatial layout of the represented scene
Images represent information about all the shapes and sizes within the scene, and it will
also preserve a diverse set of spatial relationships (relationships such as one point being
between two other points, or aligned with other points)
Thus, images directly represent the geometry of the scene, allow images to depict
the scene rather than describing it
Mental Rotation
Subjects were asked whether displays (look below) showed two different shapes or just
one shape viewed from two different perspectives
Mental rotation task: a process that subjects seem to use in comparing one imaged form
to another; to make the comparison, subjects seem to imagine one form rotating into
alignment with the other, so that the forms can be compared
The number of time it takes depends on how much rotation is needed
Imagined “movement” resembles actual movement: the farther one has to image a form
rotating, the longer the evaluation takes
People have no trouble with mental rotation in depth; they make very few errors (with
accuracy levels around 95%); the data resembles those obtained with picture-plane
rotation
In both, (2-D) picture-plane and (3-D) depth pairs, there is a clear relation between
angle of rotation and response times, and the speed of rotation seems similar for both
Visual images are not mental picture; they are more like mental s
Avoiding Concerns About Demand Character
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