Cognitive Psychology: Chapter 11
- A variety of day-to-day problems seem to require the use of visual imagery
How many windows are in your apartment?
Was David in class yesterday?
Will this sweater look good with your blue pants?
- What is the nature of these mental images?
- Francis Galton (1883) used the method of introspection to study mental imagery
- His participants’ self-reports suggested that they could inspect their images in much the same way as a picture
- The participants also differed widely in the amount of detail their mental images seemed to contain (Or were
these differences in self-reporting style?)
- Studies of visual imagery in the last fifty years have avoided introspection and instead ask participants to do
something with their images – to read information off them or manipulate them in some way
- Chronometric studies measure the amount of time required by a cognitive process of interest
- Kosslyn (1976) asked participants to answer yes/no questions about their mental images
•If participants imagined a cat, they were faster to confirm that cats have heads, compared to confirming
that cats have claws
• The reverse was true if the participants were asked to think about cats, not to imagine them.
• This suggests that as the mode of representation changes, so does the pattern of information
- Other studies have used the image-scanning procedure to study mental imagery
- Kosslyn et al. (1978) first asked participants to memorize this map
- They were then asked to mentally scan from one landmark to another on the imagined map
- The time it took to scan the image corresponded to the distance on the map
- Thus, mental images seem to preserve the spatial layout and geometry of the represented scene
- The mental-rotation task also suggests that mental images preserve spatial information in
- In each pair, are the objects identical, despite being viewed from different perspectives?
- The data from this task suggest that the greater the angle of rotation between the two pictures, the longer the
- It is as if the participants are rotating their mental images of the two objects into alignment
- Did the image-scanning and mental-rotation experiments have demand character, or cues that signaled to the
participants how they were “supposed to behave” by the experimenter? - These two results are observed even without instruction to use imagery, suggesting that participants
spontaneously form mental images and scan them
- Mental imagery seems to use perceptual mechanisms
- Visual imagery interferes with detecting dim visual stimuli, and auditory imagery interferes with detecting quiet
- Interference between imagery and perception occurs when we try to visualize one thing while perceiving another
- However, if we are imagining a stimulus related to the one we are about to perceive, facilitation occurs
- Neuroscience data also support the link between perception and imagery
• The same occipital areas used for early visual processing are activated during visual imagery
• Patients with unilateral neglect may also neglect the left side of space in their mental images
• Disrupting visual-processing areas with transcranial magnetic stimulation (TMS) also disrupts mental
- Research also demonstrates a functional equivalence between aspects of visual imagery and visual perception
- For instance, studies of visual acuity measure how close two dots can be to each other and still appear distinct
- For both perception and imagery, acuity is greatly reduced if the dots are not in the center of vision
- People who have been blind since birth also demonstrate the same effects in mental-rotation or image-scanning
tasks, with response time being proportional to the distance traveled
- Thus, we need to distinguish between visual imagery and spatial imagery
- Spatial imagery may be based in movement or body imagery, or it may be abstract and not tied to any one sense
- Individual differences in the ability to form mental imagery also suggests a distinction between visual and spatial
- Self-reported “vivid imagers” perform no differently than “non-imagers” on tasks that depend on spatial imagery
- However, vivid imagers are better on tasks that specifically require visual imagery
- Some researchers believe that five percent of all children have what is known as eidetic imagery, an extremely