Psych 351A: Midterm 2 Review (Visual Imagery)

Visual imagery

Seeing in the absence of a visual stimulus

What are the 2 questions we ask regarding visual imagery

1. Do we represent imagery in the same way we represent perceptions

2. Do we process imagery in the same way we process perceptions

Kosslyn Picture Experiment (1975)

Participants memorize a picture and then generate a mental image of it, then asked to move from one part of the image of the other (typically done with a boat and highly identifiable characteristics)

What were the findings of the Kosslyn picture experiment

That longer mental distance lead to a longer RT, concluded that visual imagery works in a similar way to regular imagery (have to trace over the image)

What did Lea (1975) argue regarding the Kosslyn picture experiment

That the more distractions one has when scanning longer distances may be what is causing the increased time, not the mental distance traveled

How did Kosslyn disregard Lea’s idea

Had individuals study a map in their minds eye and move from one location to another with some paths having intervening cities in between, found that it took longer to scan between greater distances, and there was no difference if there were intervening cities

What did Pylyshyn (1973) argue in opposition to the visuospatial component of the minds eye

Said it was propositional, was able to be represented by abstract symbols, and that spatial representation is an epiphenomenon

Epiphenomenon

Something that accompanies a real mechanism but is not actually a part of it

What did Pylyshyn find when he re-did the boat experiment but with extra links

Found that it took longer to scan

Tacit-knowledge explanation

Counter the map example, argues that we can accomplish the map task by using real world knowledge unconsciously regarding traversal, such that we slow our reaction time to match what we would actually expect

How did Finke and Pinker present counter evidence to Pylyshyn’s tacit knowledge claim using their arrow pointing experiment

Had participants view a screen with a few dots, then an arrow pointing to a location would appear, asked to judge if it was pointing to a dot. Found the further away the dot was from an arrow the longer it would take to respond

What did Finke and Pinker’s arrow pointing experiment demonstrate regarding mental imagery

That we use mental imagery even when not instructed to and that we still have a slower reaction time even when location is not memorized

What hypothesis did Kosslyn test regarding mental imagery and animals in 1978

Believed there to be a relationship between viewing distance and ability to perceive details, tested this with asking people to imagine a small animal and a large animal standing next to each other. Found longer reaction time when one asked to pick out characteristics of smaller animal

What did Perky’s 1910 unconscious backlit experiment demonstrate

Individual would stare at a seemingly blank screen that had a backlit projection of an object that escaped conscious perception, then asked participant to imagine the same object. Participant would describe characteristics of the primed object as they confused mental image and perception

What was Farah’s 1985 Letter experiment and what did it find

Asked patient to imagine a letter, the would either flash a blank screen then a letter, or a letter and then a blank screen. Asked participants if letter was flashed first or second and found that one would respond more accurately if the letter presented was the same as the one imagined

What are brain based approaches to mental imagery

Question what happens in one’s brain when they imagine an object compared to when they see it

Krieman’s (2000) single cell brain based approach to mental imagery experiment and findings

Recorded the single cells of patients in the medial temporal lobe, showed them pictures of objects and had them imagine the same objects. Found that the neurons were category specific, they also responded to imagining the same object

LeBihan (1993) fMRI brain based approach to mental imagery experiment and findings

Looked at fMRI readings of individuals who imagined and viewed the same stimulus, found activation in V1 on both their perception and mental imagery attempts (slightly weaker for latter)

Ganis and Coworkers (2004) letter and tree brain based approach to mental imagery experiment and findings

Participants were asked to either view or imagine an image (typically a tree), while hearing a letter (W or T), report if the object was wider or taller and looked at brain activation. Found that for the front and mid brain there was no difference in activation between imagery and perception. The back of the brain had a very slight difference with slightly more activation in V1 for perception

What 2 conclusions can we draw from brain based mental imagery findings

1. That the brain is active during imagery

2. Brain activation may not be necessary for imagery (could be an epiphenomenon)

How did Kosslyn (1999) prove that imagery and perception were both caused by the visual cortex

By applying transcranial magnetic stimulation to the visual cortex during imagery and perceptual tasks, lead to the areas being impaired, can conclude causal role

Mental walk task

Individual asked to visualize an animal and see how long it takes one to mentally walk towards that animal such that it can not be fully seen in FOV

What did Farah find regarding the mental walk task with regard to patient MGS

Tested MGS before and after surgery to occipital lobe, found that the image of the same animal had become smaller after portion of occipital lobe was removed, minds eye had also shrunk

Unilateral neglect

Individuals with damage to the parietal lobe, ignore one half of their visual field in perception and imagery

Piazza del Duoma experiment

Have a patient imagine standing at the south end of the square from their hometown and ask them to describe what they see. No matter what side they stood on, or what they had already seen they would only report things on the right side of their FOV

Patient RM

Damage to left occipital and parietal lobes, could copy images he could see, but not draw images from memory (impaired on imagery)

Patient CK

Inability to name pictures of objects (even one’s he had drawn) but could draw detailed objects from memory (impaired on perception)

T or F: Patient CK could recognize components of images but not the whole image

T, had trouble drawing connections to see a whole image

What do patients RM and CK demonstrate

Double dissociation, that there are separate mechanisms involved in imagery and perception

What did Behrmann argue about perception and imagery

That they partially overlap:

Perception - involves bottom-up processing, starts lower visual areas and moves up

Imagery - involves top down processing, starts at higher visual areas and moves down

What is the IV and DV in the mental rotation coglab

IV - Object similarity (reversed or normal) and rotation angle

DV - reaction time in ms

What were the two main ways in which people completed the mental rotation task and how would their results look (when graphed) on a measure of degrees of rotation

Rotate - argued there would be longer RT based on level of rotation, when graphed show a positive slope

Symbolic -  no particular reason that rotation angle to have an effect, when graphed showed a flat line

How long does it take to mentally rotate an object 120 degrees

Our trials found that it took ~1600ms

How can we calculate the extra time to mentally rotate an object

RT of rotated object - RT of non-rotated object

(assumes individual is rotating the shape in quickest possible direction

What are the 3 ways we can use imagery to improve memory

1. Chain method

2. Pegword technique

3. Method of loci

Chain method

Associate each item with a vivid image and then create a story linking the images together

Pegword technique

One memorizes a list of pegwords and then associates items to be remembered with corresponding pegwords

Method of loci

Memorize terms by mentally placing them in a familiar route along a path

What did Maguire et al (2002) find regarding mental athletes brain activation

Found their activation to be the same on general ability, but brain activations were increased with regard to memory tasks

What are the 2 types of distortions in visual imagery

1. Alignment errors

2. Rotation errors

Alignment errors

When two figures are perceived as grouped together but are misaligned

Rotation errors

Figures are remembered with respect to a frame of reference and when the natural orientation and the imaged rotation conflict the imagined orientation will be remembered as closer to the frame of reference

What were methods of Kozhevnikov, Kosslyn, & Shephard (2005) paper folding test (PFT) experiment

Classified participants as visualizers or verbalizers, had them view a folded square of paper, punched a hole in it and showed them multiple images, one of which corresponded to the unfolded square

Spatial visualizers

Spatial visualizers think best in terms of geometry, structure, and transformations

Object visualizers

Object visualizers think in terms of vivid, pictorial, and detailed images

Verbalizers

Verbalizers think in terms of words, sentences, and linguistic descriptions

Vividness of visual imagery questionnaire

Asked individuals to rate the image aroused by an item ranging from “no image” to “perfectly clear and vivid as normal vision”

What was found regarding participants that had low, intermediate and high VVIQ compared to their PFT scores

Found that high VVIQ participants had low PFT, and that low VVIQ participants had a high PFT

Degraded pictures task

One is presented with a line drawing that has portions omitted due to an obscuring visual noise pattern

What was found when comparing object visualizers and spatial visualizers on the degraded pictures and mental rotation tasks

Object visualizers did much better on the degraded pictures task and spatial visualizers did much better on the mental rotation task

What did Kozhevnikov, Motes and Hegarty (2007) find regarding the observer ball drop task, with regard to observer A

Both high and low spatial imagers were ~50% correct for observer A

What did Kozhevnikov, Motes and Hegarty (2007) find regarding the observer ball drop task, with regard to observer B

High spatial imagers - ~70% correct for observer B

Low spatial imagers - ~18% correct for observer B