PSY2001 Lecture 2 - Face Perception

Sensation

Info about environment picked up by sensory receptors and transmitted to brain

Perception

Brain’s interpretation of sensory input

Visual acuity development

Poor at birth, rapid increase in first 6 months

Near adult levels by 1 year

Definition of visual acuity

A measure of how clearly a person can see, or their ability to distinguish fine details and shapes at a distance

Visual scanning development

• Younger than 2 months: cannot track moving objects smoothly

• 1 month: focus on limited features of shape, particularly outside edges

• 2 months: start to focus on internal features

Colour vision development

• Newborns can distinguish between white and red, but not other colours (Adams et al. 1994)

• Around 1 month, look longer at brighter, bold colours

• By 4 months close to adult ability

Ways to test perceptual abilities

• Preference tests

• Habituation tests

• Conditioning

Preference tests

• Present two stimuli at same time

• Measure how long infant looks at each

• Does infant look at one more than the other

  • Infants can discriminate between stimuli

Example of preference tests

Fantz (1961)

• Infants spent a higher proportion of time looking at faces in comparison to other faces.

Habituation Tests

• Shown interesting stimulus repeatedly

  • Infant loses interest eventually (habituation)

• Change to a different stimulus

  • Infant shows renewed interest and looks again (dishabituation)

• If so, the infant can tell the difference

Conditioning

• Repeatedly reward target behaviour

  • Increase sucking rate, get specific stimuli

• Infant becomes habituated to stimulus

• Stimulus is altered (ex. HAS procedure)

  • Does not increase sucking rate → treats 2 stimuli as the same

  • Does increase sucking rate → distinguishes between 2 stimuli

Moulson et al.’s opinion on facial perception (2009)

Faces are arguably the most important visual stimulus used in human social communication.

Why facial perception is useful.

• Can recognise:

  • Species

  • Sex

  • Race

  • Identity

  • Mood, Emotional state

  • Intent, truthfulness

• Impact on social interactions

Nativism

Abilities from birth - innate, inborn

Empiricism

Acquire abilities overtime through experience – learned

Evidence for innate factial preference - Fantz (1961)

• 1-15 week old showed preference for “natural” face and jumbled face over non-face shape.

• HOWEVER… does not control for a preference for complex patterns

Evidence for innate facial preference - Maurer and Barrera (1981)

Criticism of Fantz - added controls for complexity

• 1 month: no difference in looking times

• 2 months: looked longer at “natural face”

Shows previous preference in newborns was for complexity.

Evidence for innate facial preference - Goren et al (1975)

• Used moving stimuli instead of static

• Newborns tracked proper face more than scrambled or blank

HOWEVER (Johnson et al. 1991)

• Replicated effect with newborns

• By 3 months, no longer track face more

• Why does this face preference vanished

Johnson and Morton (1991) 2 process model

Reason for reduction of facial preference at 3 months

• CONSPEC: Early system (subcortical structures) biases infants to orient towards faces

• CONLEARN: Later taken over by more mature system (visual cortex) and more precise recognition

Turati et al., 2008

Recognize identity of novel individuals

Farroni et al., 2002

• Recognize eye-gaze

  • Look more at direct than averted gaze

Field et al., 1982

• Recognize expressions

  • Infants dishabituated when expression changed

Slater et al. 2000

• Prefer attractive faces

  • Newborns < 1 week old looked longer at attractive faces

Walton et al (1992)

• Discriminate mother’s face

  • Sucked more to keep mother’s face on video

  • 1-4 days old

Pascalis et al. (1995)

• Preference for mother’s face disappeared when outside of face and hairline masked

• Newborns use outer features to identify

HOWEVER Turati et al. (2006)

• Infants could identify mother using both outer and inner features

Main findings of early face perception

• Have early preferences for faces, and even certain types of faces

• Can discriminate between different faces

• Suggests face perception is innate to some extent

Sugita (2009)

• Monkeys not exposed to faces

  • Before exposure: able to process both monkey and human faces (innate)

  • After exposure: only retained the ability to discriminate between the face types they’d been exposed to (learned)

Face perception in adults

• Narrowing of the “perceptual window”

  • As we get older, face-perception skills become more specialized

• Pascalis et al (2002)

  • 6m infants could discriminate between monkey faces and human faces

  • 9m infants and adults could only discriminate between human faces

  • If exposed to monkey faces, 9ms could discriminate (Pascalis et al 2005)

“Other-race” effect

Tanaka et al., 2004 - Adults are poorer at discriminating faces of other races compared to own race

Kelly et al., 2005 - 3m old, but not newborns, prefer own race faces

Sangrigoli et al (2005)

• Korean adults adopted between 3-9y into Caucasian families

• More accurate with Caucasian faces

Effect of exposure to primary care-giver

• Preference for female faces in 3-month-old, not newborn, infants (ex: Quinn et al. 2008)

• Fathers as primary care-givers = preference for male faces (Quinn et al. 2002)

Effect of a volatile childhood

Institutionalized children showed deficits in identifying emotions in faces (Wismer Fries & Pollak, 2004)

Children raised in abusive environment show bias for angry faces (Pollak et al., 2000)

Facial recognition in adults

• Recognize face as familiar within 0.5s

• Retain info of large number of faces

  • 90% recognition of yearbook photos

  • Class size of up to 900, up to 35 years later

Theory for late maturation

Face specific perceptual development theory

• Ongoing development of face-specific perception mechanisms; continue to develop into late child and adolescence

• Face perception gets better because of increased exposure/experience with faces

Theory for early maturation

General cognitive development theory:

• Face perception matures early (4-5 yrs - Crookes and McKone, 2009)

• Performance increases later as general cognitive mechanisms improve

Adult mechanisms of face perception - disproportionate inversion effect

• More accurate when faces are upright

• Larger effect for face versus non-face objects

Adult mechanisms of face perception - Holistic/configural processing

• Integration of info from all regions of face

• Code spacing between face and features

Evidence support for late maturation hypothesis

• Susilo et al. (2013)

• Tested over 2,000 18-33 year olds

• Controlled for non-face visual recognition, sex & own-race bias

• Positive association between age and facial recognition abilities

Twin studies on face perception

• Reveal strong genetic influence

• Depends on the face or the task

  • Differences between familiar and unfamiliar faces (Young & Burton, 2018)

Autism and social cognition

• Recognizing familiar people

• Remembering faces

• Interpreting eye-gaze and emotions

William’s syndrome

• Process unfamiliar faces atypically

• Prolonged face gaze (Riby et al. 2008)

Prosopagnosia

Face blindness

• Damage or abnormalities in right fusiform gyrus (stroke, brain injury)

• Congenital type – from birth, appears to run in families

• Different degrees of severity - may not recognise own face