Chapter 5: Perceiving Objects. Overview of Questions. Why do some perceptual psychologists say “the whole differs from the sum of its parts”? How do “rules of thumb” help us in arriving at a perception of the environment? How do we distinguish objects from their background?
Figure 5.20 The Forest Has Eyes by Bev Doolittle (1985). Can you find the 13 faces in this picture?
Figure 5.21 Grouping by (a) common region; (b) proximity; (c) connectedness; and (d) synchrony. The yellow lights blink on and off together.
Figure 5.25 (a) When the vase is perceived as figure, it is seen in front of a homogeneous dark background. (b) When the faces are seen as figure, they are seen in front of a homogeneous light background.
Figure 5.27 (a) Stimuli from Vecera et al. (2002). (b) Percentage of trials on which lower or left areas were seen as figure.
Figure 5.28 Examples of how displays that are (a) symmetrical; (b) small in size; c) oriented vertically or horizontally; or meaningful and more likely to be seen as figure.
Responses from V1 Cells (Adapted from Lamme et al., 1995.) symmetrical; (b) small in size; c) oriented vertically or horizontally; or meaningful and more likely to be seen as figure.
Figure 5.30 Left: Photographs like the ones taken by the participants in Coppola et al.’s (1998) experiment as they walked around the Duke University campus. The results of a computer analysis of the orientation in each type of scene (indoor campus, outdoor campus, and in the forest).
Structural-description model proposed by David Marr (1982) Recognize Objects?
Can you Recover the Components? Recognize Objects?
Only one view is stored, so only one is recognized. (Supports a 2D storage model)
Activity in FFA is not passively processing info, It is influenced by attention and the task at hand.
Figure 5.42 Delayed-matching-to-sample procedure. influenced by attention and the task at hand.
Decide and Act influenced by attention and the task at hand.
Perceive and Classify
Figure 5.43 (a) Response of a monkey IT neuron that responds better to a 100-percent dog stimulus (red line) than to a 100-percent cat stimulus (blue) during the “sample” period of the delayed-matching-to-sample task. Other combinations of dog and cat fell between these two extremes. (b) Response of PF neurons to the same stimuli. For this neuron, the response to dog is greater during the delay and text periods. (From Freedman, D. J. et al., (2003). A comparison of primate prefrontal and inferior temporal cortices during visual categorization. Journal of Neuroscience, 23, 5235-5246.)
Figure 5.44 The display in (a) looks like (b) -- a blue rectangle in front of a red rectangle -- but it could be (c), a blue rectangle and an appropriately positioned 6-sided red figure.
Stimuli used in Steven Palmer’s (1975) experiment. The scene at the left is presented first, then one of the objects on the right is presented. The observer is then asked to identify if one of the objects on the right was presented.
Figure 5.47 Why does (a) look like indentations in the sand and (b) look like mounds of sand? See text for explanation.
Figure 5.46 (a) Some of these discs are perceived as jutting out, and some are perceived as indentations. (b) Light coming from above will illuminate the top of a shape that is jutting out, and (c) the bottom of an indentation.