2650 Chapter 10: PSYCH 2650 Chapter 10 Notes
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Thursday, March 19, 2015
Chapter 10: Visual Knowledge
-mental pictures and the mind’s eye (these are examples that commonly illustrate the
everyday use of visual images as a basis for making decisions and an aid to
Introspecting About Images
Galton asked his research participants to look within and report on their own mental
contents and all of this had common sense: all of this implies a mode of representation
that is, in many ways, picture like that is consistent with our informal manner of
describing mental images as “pictures in the head: to be inspected with the mind’s eye.
They also differed in regards to their self reports. Some included the mention of color or
size or viewing perspective and others were devoted of any visual qualities. Perhaps all
of his participants had the same imagery skill but some were cautious in how they
chose to describe their imagery while others went all out. It may reveal differences in
how people talk about their imagery rather than differences in imagery per say. We need
a more objective method of assesing these measures.
Chronometric Studies of Imagery
To gain more objective data, these experiments ask people to do something with their
images such as a judgement. In other words the data are generally time measuring and
give us a more accurate portrait of imagery than could ever be obtained with self report.
It allows us to ask what sorts of information are prominent in a mental image and what
sorts are not - evaluations of how they really are.
ex: the cat description vs. the cat drawing - what is more salient?
The point here is that the pattern of what information is included, as well as what
information is prominent, depends on the mode of presentation. For a description, the
features that are prominent will be those that are distinctive and strongly associated with
the object being described. For a depiction, distinctiveness and association won’t
matter, instead the size and position will determine what is prominent and what is not.
Study by Kosslyn: were asked to form a series of mental images and to answer yes and
no to them. The difference suggests that information that is quickly available in the
image follows the rules for pictures not photographs. There seems that people have the
option of thinking about cats via imagery and also the option of thinking of cats without
imagery; as the mode of representation changes so does the pattern of information
In another experiment, they were asked to form an image of the island and and to point
their mind’s eye at the speciﬁc landmark. The data from this image scanning procedure
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Thursday, March 19, 2015
clearly suggests that participants scan across their images at a constant rate, so that
doubling the scanning distance doubles the time required for the scan, and tripping the
distance triples the time required. In these studies, response times are directly
proportional to the amount of zoom required, suggesting once again that travel in the
image world resembles travel in the actual world - in regards to timing.
Whether you’re scanning across a mental image, or zooming in on one there’s a clear
relationship between the travel time and travel distance and travelling a greater distance
requires more time. All of this points toward the similarity between mental images and
actual out in the world pictures.
Thus, in a very real sense, the image preserves the spacial layout of the represented
scene. With this the image will necessarily represent information about all the shapes
and sizes within the scene and preserve a diverse set of spacial relationships. It’s on
this way that images directly represent the geometry of the scene and images epic the
scene rather than describing it and are more similar to pictures/maps then they are
To perform this mental rotation task, the participants seem ﬁrst to image one of the
forms rotating into alignment with the other. Then, once the forms are oriented in the
same way, participants can make their judgements. The amount of time it takes
depends on how much rotation is needed. The farther you have to image a form
rotating, the longer evaluation takes. People have trouble with mental rotating in depth.
** mental rotation in depth is easier because they are identical unlike those that show no
alignment - only by lifting the 2D plane off of the page. In some circumstances visual
images are not mental pictures they are more like mental sculptures.
Avoiding Concerns About Demand Character
Participants in these studies obviously know that movement through the world takes
time and that moving a longer distance takes more time. Perhaps therefore, the
participants simply control the timing of their responses in order to recreate the normal
pattern. Perhaps they are not imagining rotations or scanning but perhaps thinking.
One reason is that they usually want to be helpful so they do all they can to give the
experimenter good data. As a result, they are very sensitive to the demand
characteristic of the experiment - the cues that might signal how they are supposed to
behave in that situation. Another reason is that this sort of stimulation is what imagery is
all about. In this case, a longer scan or a greater rotation requires more time, not
because there really is some travel involved but because people know that these
manipulations should take more time and do their best to stimulate the process.
About the scanning and rotation data as they are, not through simulation but indeed
because of how images represent spacial layout. The results really do emerge
whenever participants are using visual imagery whether it is encouraged by the
experimenter or not.
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