PSY2002 SEMESTER 1 - WEEK 6

Question 1

what can cause sensory conflict

Answer 1

different sense providing conflicting info about sensory stimulus, conflict need to be resolved (multisensory integration problem)

Question 2

name 3 contributers to sensory uncertainty

Answer 2

perceptual limits (eg; visual resolution determined by spacing of photoreceptors in fovea)
neural noise (eg, synaptic noise)
cognitive resource limits (eg; attention)

Question 3

give an illusions example for when sensory uncertainty can occur

Answer 3

Necker cube = disambiguated by adding shadow/small bar introducing occlusion cue

Question 4

describe testing conflict between vision and touch (Rock, 1964) to investigate integration of visual and haptic info

Answer 4

create conflict via holding object but look at it via a tube
look small but feel big
found vision dominating perceived size ie visual capture

Question 5

outline research into how audition can dominate vision (Sharms, 2000) using visual flash/auditory beep

Answer 5

report number of visual flashes
auditory beeps (1-4) play during flash
found number of beep determine reported number of visual flashes = auditory capture

Question 6

what can be concluded about visual/auditory capture

Answer 6

no strict sensory hierarchy, different senses able to dominate over other

Question 7

define modality precision hypothesis

Answer 7

discrepancies are always resolved in favour of more precise or more appropriate modality
modality with highest precision (with lowest uncertainty) chosen depending on task

Question 8

according to modality precision hypothesis, what modality is chosen for spatial tasks

Answer 8

vision

Question 9

according to modality precision hypothesis, what modality is chosen for temporal tasks

Answer 9

audition

Question 10

name an issue with the modality precision or modality appropriateness hypothesis

Answer 10

misleading = not modality itself or stimulus that dominates but instead dominance determined by estimate, and how reliably it can be taken within a specific modality of given stimuli
instead, an estimate precision is better

Question 11

Ernst & Banks studied if sensory weighting is fixed or adaptable, using judgements of height of bar and discrepancies (uncertainty) between visual and haptic (tactile) input. what did they manipulate

Answer 11

to show weighting changes signals reliability, manipulated reliability of visual stimulus by adding noise to display
weight changed from visual dominance with no noise added (v reliable visual info) to haptic dominance when lots of noise added

Question 12

Ernst & Banks studied if sensory weighting is fixed or adaptable, using judgements of height of bar and discrepancies (uncertainty) between visual and haptic (tactile) input. what should they find

Answer 12

behaviour change from visual to haptic capture
vision should show that when no added noise then vision should dominate size judgement

Question 13

what is PSE

Answer 13

PSE (point of subjective equality) height where ppt equally likely to say one bar taller/shorter than other

Question 14

Ernst & Banks studied if sensory weighting is fixed or adaptable, using judgements of height of bar and discrepancies (uncertainty) between visual and haptic (tactile) input. outline set up and what ppts had to do

Answer 14

vision = VR, change height of bar and modify uncertainty by adding visual noise
haptics = force feedback change, change height of bar
ppts judge how high think bar is

Question 14

Ernst & Banks studied if sensory weighting is fixed or adaptable, using judgements of height of bar and discrepancies (uncertainty) between visual and haptic (tactile) input. what did they find

Answer 14

when no added visual noise, perception of bar height biased toward visual input
when increased visual noise, perception bar height determined by visual and haptic input
when high visual noise, perception of bar heights only determined by haptic inputs

Question 14

Ernst & Banks studied if sensory weighting is fixed or adaptable, using judgements of height of bar and discrepancies (uncertainty) between visual and haptic (tactile) input. outline method

Answer 14

presented visual bars w/ sensory conflict between haptic and visual info to compare against bar without sensory conflict and determine PSE
(manipulated sensory uncertainty of visual feedbacks)

Question 14

Newell found that visual/haptic object recognition depends on orientation of object relative to observer. when do we best recognise things visually

Answer 14

from side we learnt

Question 14

Newell found that visual/haptic object recognition depends on orientation of object relative to observer. when do we best recognise things haptically

Answer 14

from side fingers explore most

Question 15

what does sensory cooperation between differing modalities allow

Answer 15

increase info gathered, give more robust estimates

Question 15

outline neural model of sensory integration

Answer 15

observer most likely to use on-line perceptual judgements to estimate variance (its unlikely we use variance from past experiences)
each neuron has preferred orientation, respond less strong in other orientation
when stimulated population activity has clearly defined peak marking orientation and also some variance

Question 16

define normative model

Answer 16

how problems should be solved, an optimal solution, based on theory
and can establish bounds (best that we can possibly do)

Question 17

define process model

Answer 17

how problem actually solved (based on data)

Question 18

apply normative model vs process model to finding the shortest path between home and work

Answer 18

normative= compare length for all route and pick shortest
process= choose between small number of salient options

Question 19

outline integrated signals method

Answer 19

integrate vision and haptic to reduce both visual and haptic uncertainty to form integrated signal

Question 20

outline integration signals in Ernst study, how it solves issues

Answer 20

haptic input is 50, visual is 60 = causes sensory conflict
but
combined is in-between, meaning 55 and so means the more sensory inputs means smaller uncertainty
combined estimates are biased toward visual etstimate

Question 21

why is combined/integrated signal model good

Answer 21

1. allow future numerical prediction for experiments if people are following this specific model exactly
2. able to compare prediction and actual result
3. normative models applied to multisens integration allow calculating optimal way to integrate info and solution is minimising sensory uncertainty after integration
4. humans act in accordance with this model and therefore integrate sensory info optimally

Question 22

what is MLE (maximum likely estimation) model

Answer 22

most efficient manner to integrate sensory info sources
first specify goal of sensory estimation and if goal is to get most reliable unbiased estimate, then variance of final estimate needs to be reduced
MLE is estimate with the lowest variance

Question 23

in MLE model, what do estimate weights need to take into account

Answer 23

info quality

Question 24

in MLE what gives most reliable estimate

Answer 24

optimally integrating sensory info
reliability of integrated estimate is sum of reliabilities of individual estimates

Question 25

human performances follow optimal sensory integration rules. what is visual weight range from

Answer 25

1-0 (1 is fully just trusting our vision)
linear weighting rule to integrate signals where weights depend on signal reliability

Question 26

explain how the MLE approach is bottom-up

Answer 26

prior knowledge not used
to include this need extending model

Question 27

when do we form weighted averages of motion and disparity signals

Answer 27

when asked to report an objects shape,
same for texture and disparity of depth
visual perception of slant
judgement of texture-defined edges
estimating distance

Question 28

when is vision most precise, and when proporioceptions most precise

Answer 28

when discriminating along horizontal vs depth discrimination but proception more reliable for discriminating along depth than horizontal
suggsting an MLE curve between 2 visually and proprioceptively specified location

Question 29

what are issues with optimal integration (do we always integrate info optimally)

Answer 29

need to know uncertainty which is hard to estimate (easier in sensory perception >cog reasoning)
and calculation takes long times (can use heuristic but are suboptimal)

Question 30

are probabilities encoded in brain?

Answer 30

little direct electrophysiological evidence

Question 31

what is correspondence problem

Answer 31

if can hear and see something does it mean there are 2 things, or is it the same

Question 32

in correspondence problem, when are things integrated

Answer 32

if sound like from same place
but if what you see/hear seems different (see dog and hear cat), then this is more complex

Question 33

in correspondence problem, when are signals most likely to be integrated

Answer 33

if occur simultaneously with no spatial discrepancy and not likely to be integrated when spatial discrep large, or temporal sequence of event not appropriate

Question 34

how can optimal integration behaviours be studied

Answer 34

forced-choice discrimination paradigm, ppt compare perceived sizes