Chapter 10- Visual imagery Flashcards
Visual imagery
Seeing in the absence of a visual stimulus
Mental imagery
A broad term that refers to the ability to re-create the physical world in the absence of a stimulus. Includes all senses, like auditory or tactile. Also has a role in thinking about the future, like what your friend would look like with a different haircut.
Imageless thought debate
Wundt proposed that because images accompany thought, studying images are a way of studying thinking. The link between imagery and thinking created the imageless thought debate- some psychologists believed that thought couldn’t occur without an image, others believed it could. Behaviorists believed that the study of images wasn’t productive because the images were only visible to one person
Paired-associate learning
Participants are presented with pairs of words during a study period. Then, during the test period, participants were presented with the first word from each pair. The task was to recall the other word in the pair that was presented during the study period. Used by Paivio
Conceptual peg hypothesis
Paivio- States that concrete nouns create images that other words can hang onto. When the word that generated the image is presented again, the image reappears and triggers the retrieval of the second word. This hypothesis was used to explain the finding that it’s easier to remember concrete nouns than it is to remember abstract nouns- used paired-associate learning
Mental chronometry experiment
Shepard and Metzler- determined the amount of time that’s necessary to carry out cognitive tasks. Participants were shown pictures of geometric figures that required mental rotation to be compared. Participants indicated whether the objects were the same or different as quickly as possible. The time it took to decide whether the objects matched was directly related to the degree of mental rotation required. This study is one of the first to use quantitative methods for imagery and to suggest that imagery and perception could share some of the same mechanisms. Provides evidence that people can mentally rotate objects as they would in the real world.
Mental scanning
Participants create mental images and then scan them in their minds.
Kosslyn mental scanning experiments
In one experiment, participants were told to memorize a picture, like a boat. They created an image in their mind and were told to focus on one part of the boat (the anchor) and then to mentally search for another part (the motor). Imagery was thought to be spatial like perception, and the results showed that it takes longer for participants to find parts farther from their initial point of focus. To address the concern that distractions were the factor that increased reaction time, Kosslyn did another experiment where participants were asked to picture locations on an island. Rt still increased with longer distances.
Imagery debate (Pylshyn vs Kosslyn)
Pylyshyn proposed another explanation for Kosslyn’s results. This started a debate about whether imagery is based on spatial mechanisms (like perception) or propositional mechanisms
Propositional mechanisms
Mechanisms related to language. Includes thought/statements, relations between objects, functions (type or color), or higher order structure (cause and effect)
Spatial representations
Representations in which different parts of an image can be described as corresponding to specific locations in space. Kosslyn proposed that this is the mechanism responsible for imagery. These representations involve a spatial layout of the scene that would be represented in the picture. This idea is more heavily supported by evidence than the propositional approach
Epiphenomenon
Something that accompanies a mechanism but is not actually part of the mechanism. Pylyshyn argued that the spatial experience of mental images is not part of the real mechanism
Propositional representations
Representations in which relationships can be represented by abstract symbols, like an equation or statements of what is occurring in the image. In the boat example, a propositional representation would involve nodes representing each part of the boat with lines connecting them, indicating how many nodes would have to be traveled through to get to different parts of the boat.
Depictive representations
Spatial representations where parts of the representation correspond to parts of the object
Kosslyn visual field experiment
Kosslyn made an observation that objects are seen more clearly when the object fills more of a person’s visual field- detail is a function of the size of an image. He asked participants to imagine two animals standing next to each other, like an elephant and a rabbit, and to picture themselves standing at a position where the larger animal filled their visual field. He then asked questions about the characteristics of each animal. Participants answered questions more rapidly when the animal filled their visual field. Context (which animal was paired) affected reaction time. Conclusion- differences in size are represented in visual images
Mental walk task (Kosslyn)
Participants were told to imagine they were walking closer to an animal, and to estimate how far away they were when they began experiencing overflow- when the image began to fill the visual field. This distance was smaller for small animals. These results suggest that images are spatial, just like perception.
Interactions between perception and imagery (Perky)
Participants were asked to “project” images onto a screen. The researchers were actually secretly projecting dim versions of images onto the screen. Participants’ descriptions of their mental images matched the projection images, and none of them realized that they were actually seeing an image. This suggests that participants mistook an actual picture for a mental image, and that perception and imagery interact
Interactions between perception and imagery (Farrah)
Participants were asked to imagine a letter T or H on a screen. Then, squares flashed on the screen, with one of them containing a target letter. Participants were asked to indicate whether the target letter was presented on the right or left side. Responses for the target letter were faster when the letter was the same as the letter the participants had imagined. This suggests that perception and imagery share mechanisms, or that imagery affects perception
Single neuron recordings in humans
These are rare, but usually done with patients who had epilepsy that could not be controlled by drugs. A cure could be created by removing a small area of the brain called the epileptic focus, where seizures originate. Electrodes are implanted in these patients’ brains to pinpoint the location of seizures, but the electrodes can also be used to study how the neurons respond when patients carry out certain cognitive activities.
Imagery neurons
Kreiman found that there were neurons that responded to some objects but not others. When the person closed their eyes and imagined the same object that the neuron responded to visually, the same neuron would still fire. These results provide a physiological mechanism for imagery and also provide evidence for the relation between perception and imagery.
Le Bihan brain imaging studies on imagery
Le Bihan’s study found that both perception and imagery activate the visual cortex. Activity in the striate cortex increased both with actual visual stimuli and when imagining the stimulus. When participants were asked imagery questions, there was a greater response in the visual cortex than there was for nonimagery questions.
Kosslyn brain imaging experiment
Looking at small objects causes activity in the back of the visual cortex, while looking at large objects causes activity in the front. Participants were asked to create small, medium, and large mental images during their scan. Small visual images caused activity near the back of the brain, but activation moved toward the front of the cortex as the size of the image increased, just like it does for perception.
Topographic map
Kosslyn used a topographic map for an imaging study- specific locations on a visual stimulus cause activity at specific locations in the visual cortex. Also, points next to each other on the stimulus cause activity at locations next to each other on the cortex. Evidence for similar mechanisms of imagery and perception
Ganis brain imaging experiment
Participants observed a drawing of an object. Then, for the imagery condition, participants were asked to imagine a picture they had studied before. They were asked questions about both the perception and imagery tasks. Perception and imagery activate the same areas in the frontal lobe. However, perception activates much more of the visual cortex in the occipital lobe. This makes sense because signals from the retina go to the occipital lobe when they first reach the cortex. Other experiments have found that areas associated with nonvisual stimuli, like hearing and touch, have decreased activity during imagery, probably so there is less interference with the more fragile image.
