Infant Face Perception and Processing PDF

Module 8 Chapter 12: How Infants Perceive and Process Faces Do Infants Like Faces? Infants are interested in faces in the first few months of life, but not the rest of the body until 18 months Face-Processing Abilities at Birth Infants can discriminate between schematic and scrambled faces, and some...

Module 8 Chapter 12: How Infants Perceive and Process Faces Do Infants Like Faces? Infants are interested in faces in the first few months of life, but not the rest of the body until 18 months Face-Processing Abilities at Birth Infants can discriminate between schematic and scrambled faces, and sometimes prefer schematic. Either way, they attend to faces ○ Some say its because of their dynamic and interesting characteristics and contrasts ○ Some say its because infants are born with an innate “face-detecting” brain mechanism The Development of Face Processing during Infancy 1-2 months of age: preference for face disappears 2-3 months: preference for face resurfaces ○ 1 months old rarely fixate on a face and only look at its external features ○ 2 month olds will fixate on a face and look at its internal features ○ Cortical regions of brain becoming more specialized for face processing ○ Increasing sensitivity to contrast emerging 3 months: infants interest in faces is influenced by experiences with faces as a social stimulus ○ Could be the same mechanism present at birth developing over time ○ Could be a separate mechanism at play from 3 months on than is seen at birth 4 months: infants show left visual field/right hemisphere advantage in face processing ○ Cortical responses to faces become more localized 3-6 months old respond to faces differently depending on species and orientation of face, like adults do ○ The difference? Adults show a SMALLER amplitude response to human upright faces, opposite of infants ○ Infants: One event-related potential (ERP) component for type of face = larger amplitude for human type of face Other ERP component for orientation of face = larger amplitude for upright rather than inverted faces ○ ERP component measures the brain response, and needs further development in infants 3 months: infants have difficulty 1) discriminating to facial expressions and 2) recognizing faces when they are inverted as opposed to upright 6 months old can easily recognize both human and monkey faces, but 9 month olds easily discriminate between human faces only ○ By 9 months their discrimination abilities are more specialized to humans The Role of Experience in Infant Face Processing Face perception gets more specialized based on what the infant is exposed to ○ Infants have more experience with upright than inverted faces, and human than monkey faces. Also seen in the race and sex of the face the infant is exposed to Formation of facial prototypes is present at birth but disappears from 1-3 months ○ 3 months and older can consult this prototype when processing new faces Infant Face Recognition There are separate brain systems for processing “faceness” vs processing individual faces Recognition of the Mother’s Face Most important and likely face for the infant to recognize, perhaps shortly after birth (2 day olds prefer their mothers face over a strangers!) ○ This occurs when the mother’s smell is masked also Infants suck more rapidly to prolong a video of their mother vs a female stranger Might be an evolutionary process that ensures proximity between newborns and mothers Might be a specialized system for recognizing mother’s faces that differs from the system to recognize other faces Newborns of depressed mothers take longer to habituate to her face and show no preference for it Newborns need to see both their mother’s internal AND external face features to recognize it ○ 1.25-2 months: infants only need to see the internal features for recognition ○ 4 months: infants only need to see external features for recognition 1 month: infants look longer at strangers face than mothers IF accompanied by stranger’s or mother’s speech ○ 5 months: infants look longer at a stranger face without speech ○ Infants are now familiar with mother’s face and are interested in new faces ○ Infants still show more affect looking at mothers rather than stranger’s face 6 months: no diff in looking time between stranger vs mothers face when the two are paired together ○ ERPs show the brain reacts to the mothers face as diff from the strangers These ERPS remain strong until 24 months to establish a good representation of the mothers face After 24 months, child begins stronger responses towards novel faces Recognition of the Father’s Face Recognition of father’s face forms later, and the mechanisms may be diff than those used towards mothers face ○ Research shows no preference from infants to 4 months for fathers face over a stranger male’s face Recognition of Other Faces 2-3 months: infants can tell difference between one female face and a similar female face ○ They use both internal and external or internal features only to encode a stranger’s face 3 months: ERPS differ when seeing a familiar vs novel face if they’ve had sufficient exposure to the familiar face ○ 8 months: infants ERPS differ even if exposure to the familiar face was brief 6 month boys and 3 month girls: recognized a frontal smiling view of female after seeing it in diff views 2 mins or 24 hrs earlier 7 months: infants recognize a ¾ view of face after seeing a frontal view 12 months: infants recognize a profile view and can recognize a face after something has been added/taken away from the face area (scarf, hat) ○ Recognition improves in the first year from different angles and accessories ○ If person is completing activity, the activity competes for the infants attention and they dont show as good of recognition Infants use featural info (eyes, nose, mouth) and configural info (spacing or relation amongst features) to process/recognize faces Infants with regular visual exposure to faces take less time in the first year to process/recognize faces and more efficiently look back and forth between two faces ○ Preterm babies fall behind in this development Visual acuity improves → infants can see ppl far away more easily → featural and configural info is used to encode faces Lateralization begins: 4-5 months: infants use right hemisphere more than left for recognizing faces, suggesting right hemisphere has become specialized for facial recognition and suggesting a specialized brain system ○ Alternative possibility: infants have greater expertise at recognizing faces than other objects, showing a more specialized recognition response Early visual input to the left visual field (right hemisphere) and type of input is important for this development ○ Better recognition of female faces and those of their own race (most exposure) Recognition of their Own Face 4-5 months: infants look longer at a video of another person or object with facial features than a video of themselves (suggesting they recognize their own face) 8 months: infants look longer at a static image of another person than themself ○ Likely that infants use simultaneity of actions and movements to learn about their faces, making static discrimination harder 18-24 months: mirror self-recognition occurs, along with a spontaneous visual preference for self-image (suggesting a period of greater interest in and awareness of self) Infants’ Preference for Different Types of Faces Infants’ Facial Preferences The sex of the infant’s primary caregiver is the sex that the infant will prefer to look at when shown a pair of male and female novel faces ○ Usually its female Newborns prefer to look at attractive faces, particularly attractive female faces and sometimes infant faces. Results for male faces are mixed 12 months: infants play with and show more positive affect towards an attractive stranger than an unattractive one, and avoid unattractive strangers more ○ This elicits differential social responses to strangers as the infants age The Origins of Facial Preferences Preferences for attractive female faces are based on internal rather than external facial features ○ Faces needed to be upright to elicit these preferences ○ Internal facial configurations rather than facial features elicit this interest Individuals prefer prototypes; configurations close to the prototype (“average”) are considered more attractive ○ Infants and adults may prefer attractive females because they are closer to the average prototype (facial configuration) of the female population If a more average female face is paired with a less average female face, infants may look longer at the less average face due to its oddity Other Explanations Symmetry may play a part in facial preference, but only sometimes How Do Preferences for ‘Averageness’ Develop? Infants may be born with a mechanism that allows them to average examples of faces within a category ○ Members resembling the prototype should be more preferred than members that deviate ○ Facial prototypes are formed through experiences with faces Do Infants Average across Faces to Form Prototypes? 6 month olds found prototype faces to be more familiar than either a novel face or a familiar face previously seen before. ○ Newborns and 3 month olds (but not in between) also have the ability to average faces Newborns between 14-151 hrs show preference for attractiveness, suggesting experience with faces doesnt need to be large to form prototypes Young infants dont seem to form prototypes for male faces, possibly because the majority of infants have female main caregivers Rudiments of a Stereotype: ‘Beauty is Good’ ‘Beauty is good’ stereotype: people assign positive qualities to people they fnd attractive, and negative traits to people they find unattractive 6 months: infants can categorize attractive and unattractive female faces together respectively, and treat attractive female faces as familiar after exposure to them but unattractive faces as different (and vice versa). ○ They also discriminated between the female faces in each category, showing they recognize invariant features and dont just treat all the faces in one category as one face 12 month olds look longer at an attractive face when pleasant visual and vocal stimuli are presented, and longer at an unattractive face when unpleasant visual and vocal stimuli are presented An Overview of the Development of Attractiveness Preferences Infants show differential social responses to attractive and unattractive female faces, and begin to show signs of the ‘beauty is good’ stereotype Perceiving Emotional Expressions Recognizing and Discriminating Emotional Expressions Newborns can discriminate between and imitate certain facial expressions such as happy, sad, and surprised 3 months: infants can use pics of faces to discriminate between their mother or a female stranger posing diff facial expressions like smiling and frowning 7 month olds show distinct ERP neural responses to happy and fearful expressions The maternal emotional environment and infant’s familiarity with the person portraying emotions affect the development of discrimination ability Infant girls might be more advanced at emotional processing than infant boys Infants may use features to detect differences in emotional expressions, but might not know what these expressions mean until later The Categorization of Emotional Expressions 4-7 months: infants can categorize some emotions (ex. A smile belongs to the category “happiness”, regardless of the intensity of the smile or teeth being shown) 7 month olds categorize happy but not fearful faces. They likely have more experience with happy faces ○ Infants categorize familiar facial expressions earlier than others, suggesting some recognition of faces is innate and some is learned 7 months: infants can categorize facial expressions regardless of intensity and the expressions dont need to be prototypical in order to categorize 10 months: infants begin to learn to categorize different types of emotions into ‘positive’ and ‘negative’ emotions 8 months: infants use both features and expressions to categorize facial expressions, rather than just features ○ The actual facial features used to categorize expressions vary according to the faces and which features change during expressions Understanding Emotional Expressions 7 months: infants look longer at a face displaying the same expression as the voice being played 4-6 months: infants show more positive behaviours in response to happy facial expressions, more negative behaviours in response to angry facial expressions, and no difference between behaviours in response to neutral expressions ○ 4 months old may have some understanding of the affective meaning of diff expressions The Role of Faces for Social Development Eye Contact and Eye Gaze 2 months: infants begin to look at faces more, particularly the eyes ○ They may realize the eyes are socially meaningful ○ Important for developing social bonds. When the infant shows attention by looking at caregiver’s eyes, the caregiver is encouraged to engage with the infant ○ Infants are sensitive to the averted gaze of an adult; they will smile less and sometimes decrease their looking at the adult Social Expectations Still-face situation: infants are more negatively affected by unresponsive or negative expressions than they are averted eye gaze. Infants show less smiling and looking