Visual Imagery
Seeing in the absence of a visual stimulus.
Mental Imagery
A broader term that refers to the ability to re-create the sensory world in the absence of physical stimuli, is used to include all the senses. Like when we imagine tastes, smells, and tactile experiences.
What does imagery do?
Can provide a way of thinking that adds another dimension to the verbal techniques usually associated with thinking.
What did Wundt propose about imagery?
- Images were one of the three basic elements of consciousness, along with sensations and feelings.
- Also proposed that because images accompany thought, studying images was a way of studying thinking.
Imageless Thought Debate
A debate where people either think thought is impossible without image or possible without image.
What are Galton’s arguments for the imageless thought debate?
- He found evidence supporting the idea that imagery was not required for thinking.
- He came to this conclusion by observing the fact that people who had difficulty forming visual images were still capable of thinking.
What is the paired-associate learning experiment?
An experiment where participants are presented with pairs of words, like boat-hat or car-house. They are then presented with the first word of each pair.
Their task is to recall the word that was paired with it during the study period. Thus, if they were presented with the word boat, the correct response would be hat.
This showed Paivio that it is easier to remember concrete nouns, like trunk than it is to rememeber abstract nouns, like justice, that are difficult to image.
This is why he proposed the conceptual peg hypothesis.
What is the conceptual peg hypothesis?
Hypothesis stating that concrete nouns create images that other words can “hang onto”. Helps jog our memory to see the image.
Mental Chronometry
Determining the amount of time needed to carry out various cognitive tasks.
Shepard and Metzler Experiment and Findings
- Inferred cognitive processes by using mental chronometry.
- Used the mental rotation experiment.
- What was important about this experiment was that it was one of the first to apply quantitative methods to the study of imagery and to suggest that imagery and perception may share the same mechanisms.
Stephen Kosslyn First Mental Scanning Experiments
- Participants were asked to memorize a picture of an object, such as a boat.
- Then they had to create an image of that object in their mind, and to focus on one part of the boat, such as the anchor.
- Then they were asked to look for another part of the boat, such as the motor, and to press the “true” button when they found this part or the “false” button when they couldn’t find it.
- Kosslyn reasoned that if imagery, like perception, is spatial, then it should take longer for participants to find parts that are located farther from the initial point of focus because they would be scanning across the image.
- This is what actually happened, and Kosslyn took this evidence for the spatial nature of imagery.
What discredited Kosslyn’s first mental scanning experiment?
Glen Lea proposed that as participants scanned, they may have encountered other interesting parts of the image and this decreased their reaction time.
How did Kosslyn and coworkers conduct their second experiment?
- Asked people to imagine three to seven places on an island and imagine the trips between these places.
- Kosslyn determined the relationship between reaction time and distance shown - like in the boat experiment, it took longer to scan between greater distances on the image, a result that supports the idea that visual imagery is spatial in nature.
Imagery Debate
A debate about whether imagery is based on spatial mechanisms, such as those involved in perception, or on mechanisms related to language, called propositional mechanisms.
Spatial Representations
Representations in which different parts of an image can be described as corresponding to specific locations in space.
How did Pylynshin disagree with Kosslyn?
- Stated that just because we experience imagery as spatial does not mean that the underlying representation is spatial.
- Argues an epiphenomenon, since we don’t know what’s going on in our mind.
Epiphenomenon?
Something that accompanies the real mechanism but is not actually part of the mechanism.
What did Pylynshin propose?
- Propositional representations: Representations in which relationships can be represented by abstract symbols, such as equations or statements.
- This would involve a spatial layout showing a representation in a picture.
- Depictive representations: Spatial representations such as the picture of a cat under the table in which parts of the representation correspond to parts of the object.
Explain the size in the visual field experiment and the reason behind it.
- Essentially if something is further away it is harder to see small details of the image, but as you move closer you start seeing these details.
- Kosslyn wanted to determine if the relationship between the distance of an image and the ability to perceive details also occurs for mental images.
- Participants had to image an elephant, a bunny, and a fly.
- First, they picture these animals with the elephant taking in more of the visual field. Then asked if the bunny had whiskers.
- Then, they pictured these animals with the bunny taking up more of the visual field beside a fly.
- When the rabbit took up more of the visual field we answered questions about it’s details more quickly than when it was further away.
What is a mental walk task and it’s results?
- A task Kosslyn conducted in which participants imagined that they were walking toward their mental image of an animal.
- The task was used to estimate how far away they were from the animal when they began to experience and “overflow” which is when the image fills the visual field.
- Results show that we had to move closer for smaller animals than bigger animals.
- This result provides further evidence for the idea that images are spatial, just like perception.
What did Cheves Perky experiment show?
- Wanted to have a demonstration between perception and imagery.
- Perky asked her participants to “project” visual images of common objects onto a screen and then to describe these images.
- Perky was projecting a very dim image and the participants described the images as dim even though they didn’t know they were being shown dimmed images.
- None of the participants noticed that there was a picture on the screen. They had apparently mistaken an actual picture for a mental image.
How was Perky’s experiment replicated and what did the results show?
- Replicated by having participants image the letter H or T and then dimly showing them a picture of the letter.
- We saw that when people were imaging the one letter they were more likely to see it on the screen.
- This was interpreted as perception and imagery sharing some mechanisms.
Imagery Neurons
- Neurons that fire both when a stimulus is perceived and imagined.
- Important discovery as it demonstrates possible physiological mechanisms for imagery and because these neurons respond in the same way to perceiving an object and to imagining it, thereby supporting the idea of a close relation between perception and imagery.
How was brain imaging used to demonstrate a relation between imagery and perception?
- Found that both perception and imagery activate the visual cortex.
- Activity increased both when a person observed presentation of a real stimuli (perception) and when they imagined it (imagery).
