Failures In Somatosensation Flashcards
when do illusions occur
when rules in bodily senses are broken - mismatches etc
what kinds of somatosensory illusions are there
tactile illusions proprioceptive complex somatosensory multisensory thermoception
define tactile illusions
depend primarily on cutaneous (skin) inputs
describe the cutaneous rabbit
spaciotemporal tactile illusion
geldard and shernick 1972
to sepetate locations on arm are stimulated muliple times in quick succession (p1 & -3)
report feeling in p2 in between sites - like rabbit hopping
“phantom impression”
describe blackenburg et al 2006 evidence for the cutaneous rabbit phenomenon
activity in primary somatosensory cortex just as high for p2 as in p1 and p3
primary somatosensory cortex represents the percieved location of stimuli and not the actual location
define proprioceptive illusions
depend primarily on non-cutaneous inputs
what kind of proprioceptive illusions are there
absence of movement and visual feedback cause things like drift of limbs as proprioceptive info degrades
fool brain into believing muscle is being stretched by vibrating tendons at about 100 Hz
define complex somatosensory illusions
depend primarily on cutaneous and proprioceptive inputs
describe the aristotle illusion / tactile diplopia
when two fingers are crossed over, can feel two distinct sensations in seperate locations when put obeect between them
panzeo 1910 - middle and ring best but works with others
describe lackner 1998 complex somatosensory illusion
vibrate muscle whilst body is in certain positions can induce perceptoin of impossible feeling
msucle movement generates info of proprioceptive misinformation about limb position
define multisensory illusion
dependent on somatosensory and/or visual/auditory inputs
what kinds of multisensory illusions are there
visual
thermoception
describe visual multisensory illusion
hand image makes it appear as though in diff position to reality
perception of hand as in between real and image
works with dummy hand
describe botvinik and cohen 1999 visual tactile illusion
pps view dummy hand stroked by paintbrush
feel ldentical stokes on own hand which is out of view
describe the thermoception heat grill illusion
warm and cold bars interweaved across skin
report burning heat and freezing cold pains
what is craig et al 1996’s perspective on the thermoception illusion
combination of warm and cool activates anterior cingulate - linked to pain
individually this does not occur - sent to insula
what is multisensory perception
recieve multiple sensory cues at the same time and there must be coordinated etc
can contradict
define visual dominance
visual perception is very compelling
tends to dominate our perception over info from other senses
describe the ventriliquist effect
howard and templeton 1966
sound from diff location appears as thought coming from dummy as mouth is moving
tv sounds as though coming from characters when coming from one location
describe rock and victor 1964 on visual dominance
visual shape dominates over haptic shape
draw object as view it and not as feel it from tactile senses
unaware of conflict
describe shams, kamitani and shimojo 2000 and auditory dominance
pps shown disk flashing on screen with two beeps - report two flashes
as no beeps increases, the illusion stops working - must be in same time frame as visual stimuli
control group with no auditory report correct
why do certain senses dominate at certain times
welch and warren 1986
“modality precision”
vision tends to dominate for spacial tasks and autition tends to dominate for temporal judgement
describe watkins shams haynes and rees 2005 findings after hams, kamitani and shimojo 2000 study
fmri find increased activity in primary visual cortex during illusion
processing of information changes the perception of the physical stimuli
define modality precision
accuracy and precision of sensory modalities can determine the weight of dominance put on a sense
vision tends to be most accurate so rely on more
