C4 Mental imagery

lec slideis on neglectistä asiaa

sensory modalities(?)

visual, olfactory, gustatory, tactile, auditory

overlap in visual perception and imagery processing

the two processes use partly the same MITÄÄ

there is debate about the extent to which perception/attention and mental imagery use the same processes

Roland and Friberg (1985): an early PET study (jingle, route), found that some of the same brain areas are active (in imagery and perception)

mental imagery

processing of perceptual-like information in the absence of an external source for the perceptual info

mental rehearsal in sports

epiphenomenon

JOKU that has no functional use

Santa (1977) visual vs. verbal mental imagery

lisää tähän kuva

verbal vs visual imagery

different parts of the brain are involved and information is represented and processed differently (Santa, Roland & Friberg)

mental rotation

response times are tied to the degree of angular disparity (Shepard & Metzler 1971) for both 2D and 3D

a mental process that appears analogous (vastaava) to physical action

NOT an epiphenomenon: has functional properties

related to spatial abilities in general: building LEGO

activates the parietal where-pathway

Brooks (1968): conflict between mental array and visual array scanning

diagram condition: Y/N answer for corners of a diagram (letter)

Sentence condition: Y/N answer for nouns

Y/N: pointing, tapping, saying

important finding: mental imagery and pointing to an array seem to use the same cognitive resources

Baddeley & Lieberman (1976): image scanning dual task

F-task (from the Brooks experiment) while either judging brightness levels (visual) or keeping a light beam on a pendulum while blindfolded (spatial)

spatial scanning action interfered most with the mental scanning

Moyer (1973): judging the relative size of two animals (Judgements on imagined vs physical images/objects)

done as a mental exercise: no pictures, only from memory

the smaller the difference in size, the longer the judgement time

Finke et al (1989): Judgements on imagined vs physical images/objects

Ppl can make judgments on imagined objects and come to the same conclusions as they would with seen objects

e.g. Imagine a capital letter N, connect a diagonal line from the top right corner to the bottom left corner. Now rotate the figure 90 degrees. What do you see?

Chambers and Reisberg (1985): rabbit/duck photo (Judgements on imagined vs physical images/objects)

a reversible figure was shown to participants for a short time for them to form a mental image

participants were able to interpret a reversible figure in only one way, and mental imagery did not allow them to find the other interpretation → contrast to visual perception

initial evidence that there are differences between a mental image and actual visual perception of an object

mental imagery seems mostly unambiguous (yksikäsitteinen)

another study (peterson et al 1992) found that more explicit instructions helped but was still hard

O’Craven and Kanwisher (2000): Brain areas activated by imagery vs perception (Judgements on imagined vs physical images/objects)

Task: look at or imagine faces or places

Findings:

• the parahippocampal place area activated in both imagery and perception of places (although somewhat weaker with imagery)

• the fusiform face area activated in both imagery and perception of faces (although somewhat weaker with imagery)

• = brain areas activated by imagery correspond to those activated by perception

less clarity about the primary visual cortex’s activation

Kosslyn et al (1999): transcranial magnetic stimulation (Judgements on imagined vs physical images/objects)

participants made imagery judgements slower after receiving TMS to the primary visual cortex

Judgements on imagined vs physical images/objects: STUDIES

Moyer (1973): animal sizes

Finke et al (1989) : N to hourglass

Chambers and Reisberg (1985): duck/rabbit

O’Craven and Kanwisher (2000): faces houses brain activation

Kosslyn et al (1999): TMS to primary visual cortex + imagery judgments

Levine, Warach & Farah (1985): The what and where pathways in mental imagery

a patient with bilateral (molemminpuolinen) parietal damage (where-path) could not describe locations of familiar objects but could describe appearance

a patient with a temporal lesion couldn’t describe appearance but could describe location

Cognitive maps

mental representations of the location of objects and places in the environment

route map

survey map

study: Thorndyke and Hayes-Roth (1982)

study: Hartley et al (2003)

study: london taxi drivers have higher grey matter density in posterior hippocampal structures due to strong survey maps

route map

cognitive map consisting of the paths between locations; emphasizes action info

egocentric representation

survey map

cognitive map consisting of the position of locations in space; emphasizes spatial info

allocentric representation

Thorndyke and Hayes-Roth (1982): cognitive map study

ability of secretaries to find their way around a building

findings: secretaries often used route plans, and it typically took years to form a survey map

Hartley et al (2003): neural basis of cognitive maps

participants navigated a virtual reality town in 2 conditions

• way-finding (survey map)

• route-following (route map)

TÄHÄN LISSEE

Representations of space

egocentric

allocentric

egocentric representation of space

“space as we see it”; relative to own body; relates to route maps

parietal

allocentric representation of space

not specific to a particular viewpoint; relates to survey maps

hippocampal

physical maps and mental rotation

when it isn’t possible to rotate a physical map, ppl show an effect similar to mental rotation: degree of mis-orientation affects time needed to find an object on a map (Gunzelman & Anderson 2002)

map distortion

Stevens and Coupe 1978: when ppl have to judge the relative position of two locations, they often use the larger areas to which these locations belong to for the judgements

e.g. gothenburg is west of copenhagen even though denmark is west of sweden