High-Level Perception Flashcards
What are hypercomplex cells?
Respond to bars of light. They have a larger receptive field than complex cells and may combine the signals from multiple complex cells.
What are simple cells?
Cells that respond to a particular orientation of a bar of light in a specific region of their visual field.
They are tuned - selected for a particular visual stimulus.
They provide input directly into complex cells.
What are complex cells?
Respond to a bar of light anywhere within their receptive field.
They provide input into hypercomplex cells.
Which part of monkey brains respond to faces?
Temporal cortex cells (IT, STS)
What are grandmother cells?
Specificity - respond to one object only
Generalisation - respond to this object in many instances.
Explain the Thatcher Illusion.
Upside down does not look as grotesque as upright when features are inverted.
Upright: features are analysed holistically
Inverted: Holistic face processing impaired - analysed independently.
Which features affect face familiarity?
External features are more important for unfamiliar faces
Internal features are more important for famous faces
Do face cells detect features?
Cells show selectivity but for different parts of the face.
Is the ability to recognise faces innate or learnt?
Learnt
What does face adaptation tell us?
- face coding mechanisms subject to adaption like lower-level cells
- face adaption causes suppression of face cells
- separate cells coding different identities
adaptation calibrates our visual system to the statistics of the social environment
Is the Jennefer Aniston cell a grandmother cell?
No, they seem selective but we can’t be sure that it is a grandmother cell.
How do STS (superior temporal sulcus) cells respond to face view?
The movement of the face causes the cell to fire.
Some cells will respond only to one angle, while some will respond to any angle.
What is egocentric coding in face perception?
When cells show view-sensitive coding
What is allocentric coding in face perception?
Doesn’t matter about where you’re seeing the object from, it’s about the object itself.
What is object centred coding?
When cells respond to all views of the face - object centred coding.
What do we use to work out where someone is attending?
The directed that someone is attending can be cured by the posture of the head but the eye information is also important.
You can also work out where someone is attending from their body posture information.
List which parts of the body are most important in social attention, in order of most to least important.
Eyes > head > body.
What makes a face attractive? (5)
Symmetry. Averageness. Secondary sexual traits. Skin health and colour. Hormone levels and fertility.
How does brain asymmetry affect facial processing?
Judgements of face identity, sex, age, attractiveness are biased to the left side of the face.
Because right hemisphere is specialised for face identification and emotion.
How does averageness affect facial attractiveness?
Non-average faces may indicate genotypes that are homozygous for deleterious alleles - people with unusual faces probably result from rare or uncommon genes.
How does secondary sexual traits affect facial attractiveness?
Male and female faces differ in their shapes - advertise the quality of an individual in terms of their hereditable benefits.
How does skin health and colour affect facial attractiveness?
Healthy-looking faces appear more attractive
How do hormone levels and fertility affect facial attractiveness?
Masculine characteristics - long term medical health, reproductive potential, physical strength.
Female characteristics in males - long term relationships
Female preference of faces is affected by hormone levels.
What do neurones in V4 specialise in?
Colour
What do neurones in V5 specialise in?
Motion:
Direction, speed, moving dots/bars
What are the properties of V5 cells?
- Larger receptive fields than V1 (about 3-8 degrees)
- Not sensitive to colour
What other visual areas are there in the brain outside of the occipital lobe?
Medial Superior Temporal Sulcus (MST) - motion sensitive
What are the properties of MST cells?
- Larger receptive fields than V5 cells
- Sensitive to translation, expansion, contraction, rotation
What is biological motion?
A motion that comes from actions of a biological organism.
What are different percepts from biological motion? (6)
- Actions
- Hand actions, facial actions, speech
- Gender
- Emotion
- Body weight
- Identity
What are point light stimuli?
points of light that are moving and you see them as a coordinated pattern and you derive an animate biological being from this information.
What is the pSTS?
Posterior superior temporal sulcus
How does the pSTS relate to biological motion?
It’s the region of the brain that appears to be involved in that subjective experience of animate moving body performing actions.
How does STS relate to biological motion?
STS will respond to biological motion figures in many cases.
How are inverted biological motions processed?
They are difficult to recognise.
How does sound affect biological motion recognition?
It improves biological motion recognition.
How is biological motion pervasive? (4)
- Infants preferentially observe biological motion (not autistic ones).
- Other social actions can be recognised
- Emotion can be derived from biological motion faces
- Other animals e.g. cats can discriminate biological motion.
What did Puce et al 2001 find with the STS?
There is STS activation in biological motion, but also when imagining biological motion and with facial biological motion.
How does the MTG differ from the STS in biological motion?
STS responds to the nature of moving human stimuli whereas the MTG (middle temporal gyrus) responds to rigid motion
What is a short ISI?
A biologically implausable motion - seen as object-like rather than a biological motion
What is a long ISI?
A biologically plausaible motion - activation in network of areas involved in perception of human movement.
What is implied motion?
There is a figure where no movement is occurring at all but the pattern and form of the figure implies that there is motion occurring.
What does hMT/V5 respond to? (4)
- motion>static
- illusionary motion
- implied motion
- imaginary motion during mental rotation
What is the backscroll illusion?
- walking action induces percept of grating moving
- generates the illusion that the background is moving in the opposite direction of the walker
Where in the brain is the backscroll illusion processed?
Interconnections between the superior temporal sulcus (STS) and V5.
Do STS cells respond to implied motion?
Monkeys did.
The more it lookos like it’s moving, the greater the response.
Why is action perception important? (7)
- Humans are highly social
- Successful AP affords evolutionary advantage
- Interacting in complex social environment
- Threat detection
- Building alliances
- Interaction with potential mates
- AP is fast - dedication systems?
Do neurones respond specifically to actions?
Yes
Cells respond to specific types of actions
What information do cells need to respond to actions?
Shape information anf the motion information so we know what is actually occurring.
What actions can monkey STS cells code?
- Hand actions
- Body actions
- Face actions
- Face/hand combinations
How do monkey STS cells code actions?
Population coding, not grandmother cell coding.
How do we perceive actions under different environmental conditions?
- some STS cells respond to action from one view - view-dependent coding (egocentric)
- some STS cells respond to action from any view - view-independent coding (allocentric) (object-centred coding)
What could be the possible organisation of neurones for action processing systems?
lower level inputs come together to form the view-dependent stages. these then add together to form the view-independent stages
How do we distinguish detailed properties of actions?
Lower level information may be useful:
- shape of hand
- texture of hand
- colour of hand
- view of hand
What is the EBA?
Extrastriate body area
What is the FBA?
Fusiform body area
How does the EBA respond to body parts?
Bodies > body parts > face parts > other objects
- Basically rhe more body-like the stimuli, the more active this area of the brain.
What are the similarities between the EBA and FBA?
- Respond to images of bodies over other stimuli
- Both lie close to face areas
- Both respond to biological motion stimuli
What does the OFA respond to?
Faces - Occipital Face Area
What does the LO (Lateral Occipital Area) respond to?
Objects
What does the EBA (Extrastriate Body Area) respond to?
Bodies
What is the ‘central tool’ of our mind?
Bodies are the only way we can intentionally influence the world - artificial tools are extensions of this basic tool
What do intentions consist of?
Ends - wanting something
Means - taking measures to get there
How does action perception change in children?
Infants: attend human bodies
Toddlers: understand goal-directed actions
Pre-schoolers: have a theory of mind
What does the pSTS respond to in action perception?
Representation of body movement, goals and intention
What does the TPJ (Temporal Parietal Junction) respond to in action perception?
Representation of specific contents of mental states, beliefs, Theory of Mind
Where is the EBA?
The lateral surface of the occipital cortex
Why does the mouth move?
Eating, drinking, emotive utterances, speech
Which part of the brain responds to mouth movements?
STS
Why are the perception of mouth movements important?
- perception of auditory speech
- observing others’ face improves the intelligibility of speech
- deaf and hearing people can use mouth movements to understand speech without sound
How does STS respond to sign language?
STS is more active to ASl than nonsense hand gestures so it is important in the understanding of ASL
What is emotional body language?
We are able to make inferences about the perception of people’s emotions from their actions, irrespective of their action
Which brain structures process emotional body language?
Body processing: EBA, FBA, STS
Emotion processing: amygdala, anterior cingulate etc
What is a mirror neuron?
Premotor cortex neurons that respond during execution of goal direction action - they respond to the SIGHT of the action.
What do M1 motor neurons do?
They are responsible for moving difference parts of our body - they operate single muscles
How does the premotor cortex cause actions?
Premotor cortex neurons provide input to M1 cortical neurons.
Causes movement in groups of muscles - can generate coordinated action.
How specific are mirror neurons?
They respond during specific actions - to the sight of the specific action.
When do mirror neurons respond to hidden actions?
They respond to goal-directed actions but do not respond to miming
they respond when the late part of the action is out of sight
Where are mirror neurons?
In the STS - the neurons respond selectively to actions.
Have not been found yet though.
What are MEPs?
Motor evoked potentials - electrical signals recorded from the descending motor pathways from muscles following stimulation of motor pathways within the brain.
What evidence is there for mirror neurons in humans?
- MEPs are enhanced during action observation
- Sounds also increase likelihood of MEPs
- Listening to words that use the tongue enhance MEPs in the subjects tongue.
- can see premotor cortex and parietal activity
Why have some argued that humans do not have mirror neurons?
- Evidence is indirect
- Relies on correlations between visual and motor activity
- Neuroimaging is a measure of correlation
Where has evidence found mirror neurons in humans?
- Supplementary Motor Area
- Hippocampus
Why do we have mirror neurones in the hippocampus?
- Perhaps they are distributed across the brain
- Although seems to suggest there is a concentration of these neurones clearly in the parietal region and inferior frontal gyrus (PMC)
What is the mirror neuron system for?
Perception of actions, understanding actions, understanding action intention, language?
How does the mirror neuron system allow us to understand actions?
Multiple levels of understanding:
- the goal, understand how the person feels, why they are doing the action, do they want to do the action?
What is simulation theory?
To understand other people’s actions, we simulate their actions - using our motor systems?
What is Theory Theory
We acquire and deploy a commonsense theory of mind - set of causal/explanatory laws
Do mirror neurons work for touch?
Somatosensory neurons respond during touch and observing another person being touched.
How does the mirror neuron system affect language?
Initial intentional communication was based upon hand movements and also hand-mouth and oro-facial gestures.
What can deficits in the mirror neuron system affect?
- Social Cognition
- ASD (impaired social and emotional skills)
- Physiologcal - motor activation
What is the idea of multisensory integration and tool use?
A weilded tool may be incorporated into the body schema such that the end of the tool effectively becomes an extention of the effector wielding it
What is a visual receptive field?
- The area of the visual field where light modifies the cell’s response
What is an auditory receptive field?
The area of space where sound modifies the cell’s response
What is a somatosensory receptive field?
The aea of the body surface where touch modifies the cell’s response
What is multisensory integration?
Combining either behaviourally or at neural level, inputs from more than one sense.
What are the benefits of multisensory integration?
- We can reduce uncertainty if we use more than one sense
Where does multisensory integration occur?
- Subcortically in the superior colliculus and putamen
- Cortically in association areas
What is the definiton of a tool?
Deliberate and purposeful manipulation of some kind of object used to achieve a goal
