Visual Imagery (AI)
- We all live in our heads
- Multiple forms of cognition impact our experience constantly
o Memory, visual imagery, etc.
- Mental imagery: experiencing a sensory/mental impression in the absence of visual input
o Not the result of something being there
o Ex: describing something that isn’t there
o Can correspond to any sense
- Visual imagery
- Roger Shepard and Metzler: study on visual imagery (1971)
o Gave people some unique stimuli
o Show stimuli, remove from screen, then ask if different one is same
o People mentally manipulate these in working memory
o Visual rotation task
o DV: RT
o Result: as rotational difference increased, RT for decision takes longer
§ Almost perfectly linear
o Shows we have mental representations that we can manipulate
- Men tend to give concrete directions; Women tend to rely on landmarks
o Women emphasize visual images
- Steve Kosslyn first one to study this
o First had people memorize an image
o Picture removed
o Then asked them to focus on a specific thing
o Then search for another item and click button when they find it
o Longer RT for 2 items that were farther away in original image
o Indicates that they are mentally traversing the image
- Maggie Peterson
o (Brown – Peterson task)
o Did visual imagery experiments
o Asked participants to imagine that they were in a building and walking to a different building
o In one condition: imagine you’re carrying a feather
o Carrying a bowling ball
o Press button when you get there
o RT longer for bowling ball
- Kosslyn
o Imaginary map/island
o Mentally imagine walking from A to B
o Path on map = longer RT
- Kosslyn
o Propositional representation (usually used for computers)
§ Statements about relationships
§ Simplest verbal communication that makes sense
o Hypothesis: In an image: things would be represented by proposition
§ Like the semantic network
- Humans use visual representations for tasks
- Objects closer seem bigger
o People are better at making a mental representation when object is closer (faster RT)
o According to proposition hypothesis: distance shouldn’t matter
o Takes up more space in visual field
- Imagery ß -> perception
- Perky (1910)
o Used projector
o Participant sits in front of wall/screen
o “What do you see?”
o Projector display very dim image behind wall
o Participants see the image
o Think its all in their head, not a projector
o We have a hard time distinguishing between real and in head
- What’s the relationship between visual imagery (we generate) and visual perception (real object)
- Farah (1985)
o Present visual stimulus and create mental image of stimulus
o Then either:
§ Flash Blank then stimulus
§ Flash Stimulus then blank
o Task: which came first?
§ If mental image matched the stimulus
- Single Cell recordings
o Single cell reacts similarly when perceiving a stimuli and imagining stimuli
o Doesn’t react to a different stimuli
- In some studies its impossible to have a control, so we like to be able to manipulate
- Brain imaging
o Perceive : on
o Off: off
o Imagery: on
o Off: off
o Perceive: on
- Transcranial Magnetic Stimulation (TMS)
o Big magnet on head and it disrupts brain activity in nearby region
o Try to use for depression???? Anyway….
o In this experiment:
o TMS coil in back of brain (visual processing)
o Shown stimuli and asked to make judgments
o When coil on brain: cant see it??
§ Disrupted ability to make distinctions between stimuli
- A lot of evidence that we can create visual imagery and use it to perform tasks
- Brain used similarly in imagery and perception
- Part of brain on attention: attention outwards vs. attention inwards
- Memory methods:
o Chunking
o Visual imagery
o Method of loci
§ Number = image
§ Put image at landmark you’re familiar with
§ Along path
§ In order