Lecture 7 multisensory intergration Flashcards
integration has a spatial/ temporal window
More likely to occur the closer the stimuli in different modalities are in time.
Spatial closeness also facilitates multisensory integration
What is integration assesed by
If the response will be greater and more effective if the senses were responded to individually.
Multisensory integration definition
A statistically significant difference between the number of impulses evoked by a cross-modal combination of stimuli and the number evoked by the most effective one individually
Todd 1912
Participants were asked to press a button when the light appears. When the light was shined and a sound was played reaction times decreased.
The superior colliculus
Located in the midbrain, superior to the brain stem and inferior to the thalamus.
Contains 7 layers of grey and white matter including spatial maps of different modalities.
Has high number of multisensory neurons so it is more efficient to combine senses
If there was ablation there would be disturbance to visual attention and orientation behaviours.
And loss of ability to respond to contralateral touch
Superior colliculus behavioural functions
Integrating sensory modalities
Sensorimotor transduction: Transform sensory inputs to motor commands
Realisation/ mapping: alignment of different sensory and motor maps.
Principles of MSI: inverse effectiveness
When two unimodal neurons are feeding into a bimodal neuron:
Weak cues- the response provided by the bimodal neuron will be greater than the sum of these two (super additive)
When they get stronger: Integrated response decreases in proportion though it can still be larger than individual responses.
Multisensory enhancement is inversely related to the effectiveness of the cues combined.
Principles of MSI: spatial and temporal congruency
The receptive fields of both senses must overlap in order for integration to occur.
They must also occur within the same temporal window.
There is an optimum point at which the response will be greatest.
Integration only occurs if there is a link between space and time.
sensory illusions
Assumption that detecting different sense at the same time must mean they are cause by the same event.
Audition and vision
Ventriloquist effect:
Perception of auditory location is shifted towards a visual cue.
Timing of visual and auditory cues must be aligned
Other cognitive effects which associate certain sounds with certain visual cues also play an effect.
McGurk effect:
Persons phoneme production is dubbed with a video of that person producing a different phoneme.
Leading to the development of a 3rd phoneme- Mandatory fusion
Vision and touch illusion
Rubber hand illusion:
Visual and tactile information applied synchronously leading to visual capture.
Visual and proprioception combine to judge where and what our body is. This illusion suggests vision has a greater influence on this.
Hearing and taste
Playing crunchy noises makes people perceive crisps as more crunchy
Visual and vestibular
ppt were spun around so that their vestibular system made them feel tilted.
They were then shown a horizontal line and assumed the line was tilted as it was horizontal to them and in line with them and they are tilted therefore the line must also be tilted.
Synaesthesia
Where one type of stimulus is associated with another sensory experience in another modality
idiosyncratic- people have different associations
It is consistent and people will always have the same associations.
Not learnt, but a genuine sensation that is felt.
Suggesting people may have stronger connections between brain regions and sensory areas.
