Seeing and Visualising Flashcards
What was Simons and Chabris’ experiment? What did it demonstrate?
Simons and Chabris’ experiment was the gorilla in a suit video. It demonstrated inattentional blindness.
What is change blindness?
Change blindness is the difficulty in detecting changes in a scene when the changes occur rapidly. Change blindness was illustrated by Rensink. Rensink presented one picture, followed by a grey frame and then the same scene with a change. The pictures flicked between each other until the subject was able to identify the change.
Change blindness is caused by our perceptual system being unable to focus on everything. It ignores things that are not the focus of our attention.
What was Rensink’s experiment?
Rensink’s experiment was to do with change blindness. Subjects were shown an image, followed by a blank slide and then the same image but with changes. Subjects had to identify changes in the scene. Slides were repeated until the subject answered.
What is Kosslyn’s mental scanning experiment?
In the first mental scanning experiment, Kosslyn’s subjects had to memorise an image of a boat. Subjects then had to visualise the boat in their head. The experimenter instructed the participant to focus on one part of the boat (i.e. the anchor). The subject then had to look for another part of the boat (i.e. the motor) and indicate if the part of the boat was present on the stimuli presented originally. Kosslyn found that it took longer for subjects to find parts that were further away.
In his second mental scanning experiment, Kosslyn showed participants a picture of a made up island. There were 7 locations on the island. Subjects had to scan between different pairs of locations on the island. Again, Kosslyn found that it took longer for the subject to identify locations on the island the further away they were.
Kosslyn theorised that imagery is spatial (or depictive) because of this.
What experiments argue that imagery is spatial?
Kosslyn’s mental scanning experiments (island and boat)
Finke & Pinker 4 dots
What is Finke and Pinker’s experiment?
Finke and Pinker presented subjects with an image with 4 dots on it. After a pause, subjects were then presented with an image with an arrow on it. Subjects had to indicate if the arrow was pointing to any of the dots or not. Subjects took longer to respond to dots that were further away from the dot they were pointing at.
What did Pylyshyn argue?
Pylyshyn argued that imagery is propositional in nature. Pylyshyn argued that imagery is represented by abstract symbols in the mind and is not visual in nature. He said that Kosslyn’s boat can be understood propositionally, by creating a tree diagram, with boat parts being located at nodes. The more nodes between the parts would mean a greater time to respond.
He argued the tacit-knowledge explanation and said that subjects use real world knowledge in making their judgements.
What is the tacit-knowledge explanation?
The tacit-knowledge explanation is when subjects use real world knowledge in making a judgement. Pylyshyn argued against Kosslyn’s mental scanning experiment by saying that subjects use their knowledge about boats to answer the questions
What experiments counter the tacit-knowledge explanation?
Finke and Pinker’s 4 dot experiment
Kosslyn’s mental scanning island experiment
What is inattentional blindeness?
Inattentional blindness is when a person does not see something that is clearly visible. It is illustrated by Simons and Chabris’ experiment. A video was shown to participants of two teams (black and white shirts). One team was passing the basketball between them and the other was blocking the passes. Participants were instructed to count the number of passes that the white team made. Around halfway through the video, a man dressed in a gorilla suit walked through the frame. At the end of the video Simons and Chabris asked participants if they noticed anything unusual. Most people didn’t notice the gorilla. Simons and Chabris reasoned that this is due to inattentional blindness. Subjects attention was focused on a task and they were not aware of other things occurring.
What are the similarities between imagery and perception?
- Size in the visual field - an object imagined further away only appears small with minimal detail, just like in real life. Kosslyn designed the mental walk task. Subjects had to imagine that they were walking towards mental image of animal and to stop when the animal filled their visual field. Kosslyn asked subjects to guess how far away they were from the animal. Results showed closer for smaller animals than larger animals. Kosslyn also asked subjects to imagine two animals - an elephant and a rabbit. Subjects were then asked to perceive the two animals standing side by side so that both animals are in the field of perception. He asked subjects questions about the animals (i.e. does the rabbit have whiskers?). Subjects had to find the part of the animal in the visual field and answer as quickly as possible. Participants were slower to respond when the animal was comparatively smaller (i.e. faster response when rabbit is next to a fly compared with an elephant). Theorised that the relationship is the same with viewing distance as both imagery and perception.
- Interaction of imagery and perception. Perky asked subjects to project a mental image of an object onto a screen and then describe the object. Perky dimly projected the image onto the screen without participants awareness. Subjects generally described the image in the way that she had projected the images (i.e. orientation of the banana). Farah asked subjects to mentally project either H or T in their head. The subjects were then shown two squares, with either a H or T projected. Subjects found it easier to identify the letter that they had perceived.
What is the mental walk task and who designed it?
Kosslyn designed the mental walk task. Subjects had to imagine that they were walking towards mental image of animal and to stop when the animal filled their visual field. Kosslyn asked subjects to guess how far away they were from the animal. Results showed closer for smaller animals than larger animals.
What experiments showed the size in the visual field is the same for imagery?
Kosslyn’s rabbit, elephant and fly comparison’s
Kosslyn’s mental walk task - walk towards animal until filling visual field and estimate distance
What experiments show the interaction between imagery and perception?
Perky - getting subjects to perceive an image and dimly projecting it with subjects describing the characteristics of projected object (i.e. orientation) shows interaction between features.
Farah - Subjects imagine an H and T on a screen. Two squares flashed one after the other, with either a H or a T being shown in one of the squares. Subjects had to indicate what letter was shown and in what square it was in. Subjects found it easier to identify the letter that they had imagined.
What was Farah’s challenge to the imagery vs perception debate?
Farah said that the tacit knowledge explanation cannot be ruled out entirely. She said that subjects may be conducting the mental walk task using knowledge and answering based on prior knowledge about how far away an animal should be. Farah challenged and said that research needs to be undertaken on how the brain responds to visual imagery.
