Multisensory integration - body schema Flashcards
Why are computers good at hard tasks e.g. chess?
-can make inferences and pick the best pathway out of a list of options
Moravec’s paradox
-it isn’t hard to program a robot to do hard tasks but it is difficult to give them skills of a one year old
What senses are used in the task?
-generally lots of vision, touch is needed as we need tactile feedback
What is multisensory integration?
the study of how information from the different sensory modalities may be integrated by the nervous system
Challenges in multisensory integration
- how to transform representations from different senses into a common representational space
- how to integrate info from different senses into a coherent percept
- we need to convert info between reference frames and external space
What are reference frames?
representational schemas from senses
e. g. vision–> eye-centred/retinal, location of visual stimulus on retina
e. g. audition–> head-centred, location of sound source with respect to ears
e. g. touch–> body-centred, location of tactile stimulus on skin
Coordinate transformations: dog
- looking at it - centre of vision
- hearing it bark - different reference frame (head-centred)
- eye-to-head: need to know orientation of eyes
- head-to-body: need to know orientation of head
What does converting between reference frames require?
requires us to know the position and orientation of body parts (body schema)
What is body schema?
a representation of the positions of body parts in space, which is updated during body movement
Describe body schema
- Spatial coded: position of each body part in external space
- Modular: different body parts processed in diff brain regions making it difficult to study bc it is spread out across the brain e.g. split brain
- Updated with movement
- Adaptable: changes when body changes + body changes over lifetime
- Supramodal: combines input from different senses
- Coherent: resolves perceptual conflicts (spatial continuity)
- Interpersonal: observed actions are represented in body schema
Types of body representation
- body schema: mainly used for sensorimotor tasks
- body image: concept - what the body looks like and affect - how we think about it
- structural description
- body semantics
Does body posture affect perception?
- test using temporal order judgement task: crossing arms vs uncrossed (not something body schema is needed for) - one hand is stimulated and ps need to stretch fingers of hand stimulated
- body schema can interfere with perception when arms crossed and cannot be turned off when we don’t need it
When does body schema develop?
4 months: no interference of body schema on performance when feet are crossed vs not
6 months - body schema starts to interfere with tactile orienting
Cross-modal congruency
Tactile discrimination task: determine which finger was vibrated
- visual distractor: flashing light either on same or different hand to being vibrated
- distractors lead to response delays, same hand-distractors lead to longer delays than different hand (42ms difference)
- when arms crossed, tactile stimulus on same side of body but visual on different - effect of visual distractor moves with the hand when crossing arms, cross-modal interactions mediated by body schema
What is peripersonal space?
the space immediately surrounding our bodies
- extent of space isn’t fixed e.g. can become bigger using tools
- tools are incorporated into body schema during use - cross-modal congruency effects apply when tools crossed (not arms)
