4 - social perception

why is social perception important and when can it be used?

it’s a necessary social skill to understand people, gauge danger and who’s good.

• used in sports like basketball - deceiving an opponent means a point, anticipating moves can be used to one’s advantage

todorov et al (2005)

pps were told to look at photos of ppl and decide who looked more competent. ppl use diff cues to decipher diff types of people using little to no info.

bruce & young (1986) - cog model of face perception

• structural encoding: shading (is it facing me) + curvature (is it more rounded/sharper)

• face recognition unit: matching what you see to what’s in you memory

i. neurons have similar responses to the same stimuli for months, and they’re tuned to specific features that help w/face distinguishing

• person identity node: match 3D memory rep of familiar faces:

i. linking perceptual + semantic info about a person

ii. emotional facial expressions/eye gaze help determine how to react to certain social situations

chang & tsao (2017)

• Started w/200 human faces and marked 58 points on the face.

• Used computers to make an average face

• Then examined how each face deviated from the average.

• They found that faces varied in:

i. Shape (e.g., width, height, roundness)

ii.  Appearance (e.g., openness of eyes, hairstyle).

• The researchers then found a face senstive region of the monkey inferior temporal cortex using FMRI.

• They took single cell recordings of the lateral and anterior portions of the face sensitive part.

i.  Lateral : neurons here sensitive to shape

ii. Anterior: neurons senstive to appearance.

prosopagnosia + cog model

consistent with the cognitive model, but just can’t do the face recog unit section. their deficit is through faces but can identify ppl through voices

neural basis of face perception

• dorsal (where) stream: where an object is located in a space

• ventral (what) stream: what we’re looking @

need to know what + where we’re looking @ to properly respond to situations

what lobe is associated w/dorsal stream

parietal lobe

what lobe is associated w/ventral stream

temporal lobe

pohl (1973): evidence for what and where streams

• monkeys w/bilateral temporal lesions struggled w/shape discrim (lesions impacted VENTRAL stream)

• monkeys w/bilateral parietal lesions struggled w/finding objects (lesions impacted DORSAL stream)

dorsal (where) stream

• neurons here respond to stim that enters its receptive field

• 60% of neurons exclude the fovea (responsible for central vision)

• neurons focus on peripheral vision

ventral (what) stream

• neurons ALWAYS include fovea

• focus on central vision - we look at things we’re trying to identify

• neurons are activated by specific stimuli (e.g., looking directly @ an object)

occipital face area (OFA)

ofada sauce tee hee

• specifically specialised for faces but not bodies/objects

• in ccharge of early stages of visual processing for faces (physical features)

• can respond to upright + inverted faces

• sensitive to facial expressions + other physical changes

Fox et al (2009)

any physical change influences OFA activity, and it didn’t correlate w/pps seeing a change in who the person was or their facial expression

Pitcher et al (2009): triple dissociation

used TMS to knock out these three brain regions: OFA, extrastriate body area (EBA), and lateral occiptal area:

• OFA: decreased ability to discrim faces but not objects/bodies

• lateral occipital area: decreased ability to discrim objects but not faces/bodies

• EBA: decreased ability to discrim bodies but not faces/objects

fusiform face area (FFA)

along the ventral surface of temp lobe that responds to unchanged faces (resting expression). since it’s in the WHAT stream, it helps us see WHAT face we’re seeing

FFA: expertise hypothesis

research implies it’s not specialised for faces, but rather it activates because we’re so used to seeing faces (face experts)

how did Gauthier et al., (1999) and Brants et al., (2011) support the “expertise hypothesis” (think Greebles)

researchers made fake beings called Greebles and trained ppl to be able to identify them. then wanted to see how they reacted:

• Gauthier et al (1999): greeble experts showed > FFA activation

• Brants et al (2011): pre-training pps about Greebles showed increased FFA activity

superior temporal sulcus (STS)

the STS is important for changes in the face and still identifying that it’s the same person (i.e., expression, eye gaze, movement)

what is the link b/t the STS and social cues?

the STS responds to facial changes, and facial changes are usually tied to different social cues:

• Carlin et al (2011): gaze direction → activated anterior STS

• Pitcher et al (2011): motion info in faces → posterior STS

what did Bruce & Young (1986) believe about perceiving emotional expressions?

they had an idea that there’s a separate path for facial expressions that aren’t linked to identity. for example, some patients w/brain damage can’t recognise emotions but can recognise identity:

• usually have lesions in orbitofrontal cortex/ventromedial PFC, but no lesions in the STS/FFA

what did Haxby et al (2000) suggest about recognising emotion but not identity?

sensorimotor stimulation → we understand emotion in others by mimicking them within ourselves

• like seeing someone smile, we may think of ourselves smiling (e.g., facial mimicry)

capgras delusion

a neurological condition where ppl believe that their loved ones have been replaced by an impostor

what is the importance of the capgras delusion in emotion research?

because these people have no issue with recognising who the person is (overt), but there’s a disconnect b/t the emotional response (covert) people have when recognising someone.

extrastriate body area (EBA)

located in the posterior inferior temp sulcus/middle temp gyrus. it responds to diff representations of what a body is (i.e., stick figures, photos, line drawings):

• it’s strongest to humans (expertise hypothesis again), then mammals, and weakest to smaller kinds of bodies

fusiform body area (FBA)

responds to whole bodies, body parts, and schematic depictions of body.

• partly overlaps w/FFA (Peelen & Downing, 2005) → makes sense as faces are attached to bodies

perceiving bodily emotion

body language can tell us additional info. a face might show fear and your body will either fight/flight/freeze.

• fun fact (Hadjikhani & DeGelder, 2003): regardless of the face, fearful body language activates the amygdala

trait inferences from faces & bodies

• traits: stable patterns of the way ppl think, feel, and behave (BIG 5)

• BIG 5: openness, conscientiousness, extraversion, agreeableness, neuroticism (OCEAN)

Based on minimal info extraversion seems to be easy to pick up. photos of someone’s face is good enough to predict it, and pps accurately perceived it after 50ms of exposure to a face

perceptual determinants: what facial features lead to specific impressions?

• baby-faced: weake naive, submissive

• attractive: competent, kind (halo-effect)

• masculinity: dominance

so these facial features can also link to specific emotions… anger = dominant, happy = trustworthy

non-perceptual determinants of facial features and impressions

how unique a face is causes an attractiveness rating (i.e., familiarity)

• atypical faces: < trustworthy (i’ve never seen someone who looks like that so i can’t trust it)

• ppl who look similar to loved ones are perceived more favourably

consequences of perceptual & non-perceptual determinants of facial features

• competent looking politicians receive larger vote shares and are more likely to win elections

• competent/dominant CEOs have better companies + more money

• ppl perceived as untrustworthy are more likely to receive guilty verdicts even when there’s little veidence of guilt

accuracy b/t facial expressions and first impressions

ppl are incredibly inaccurate when associating faces w/how ppl actually are

• studies find that pps rely too heavily on appearances rather than valid info preseted to them.

what is the functional significance of forming social attributions from faces?

• overgeneralisation: using easily accessible facial info (e.g., smile) to make congruent social attributions (e.g., nice person

• categorisation: assigning a face to social category, which we use to make attributions about that person

• transference: generalising qualities of loved ones to strangers who resemble them

• functionality: we make inferences often based on functional qualities