FACE RECOGNITION

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FACE RECOGNITION

• CORE READING
• Ellis, A and Young, A. (1996). Human cognitive
  neuropsychology. Psychology Press, Chap 4.
• SUPPLEMENTARY READING
• Burton, M., Bruce, V., Johnston, R. (1990).
  Understanding face recognition with an
  interactive activation model. British Journal of
  Psychology, 81, 361-380.

• AIMS OBJECTIVES
• The aim of this lecture is to review models of
  face recognition.
• At the end of the lecture you will have learned
• Modular view of face recognition
• Mechanisms in face recognition
• Models of face recognition
• What is prosopagnosia

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Adaptive reasons to recognise faces

• Evolutionary reasons
• We need to distinguish between familiar faces in
  our social groups for survival.
• Socio-cultural reasons
• We might be able to predict a persons behaviour
  from facial features.

• Genetic predisposition?
• Brain regions dedicated to recognition of faces
  (in primates too).
• Damage to this part of the brain leads to a
  recognition disorder called prosopagnosia.

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How do we recognise faces?

• When we look at a face we can extract different
  types of feature information.
• For all faces we can decide upon emotional
  expression, gender, age, etc.
• This information enables us to distinguish
  between faces and identify people.

• Feature information enables us to make
  familiarity judgements on the basis of the
  physical features of faces.
• But this does not ensure that we identify people
  correctly
• I know your face but Ive forgotten your name

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Face knowledge

• There are several levels of modular knowledge
  used in the identification of familiar faces.
• Traditional models of cognition assume these are
  accessed in stages of information processing.

• 1) Recognising a face as familiar.
• 2) Retrieving our stored biographical knowledge
  about a persons identity.
• 3) Retrieving name of the person.

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Bruce and Young model (1986)

• Non-identity related information
• Facial expression.
• Directed judgements of age, gender etc..
• Lip reading.

• Identity related information
• Face recognition units (FRUs).
• Person identity nodes (PINs).
• Name generation.

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How do we recognise faces?

• Pattern recognition.
• Structural encoding.
• Perceive and create a visual 'description' of the
  features of a face.
• shape, size, colour etc and their configuration.

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Stages in recognizing faces

• Face recognition units (FRUs).
• Matching the visual description of a seen face
  against stored descriptions of the appearance of
  familiar faces seen before.

• Person identity nodes (PINs).
• Access to biographical information held in
  long-term memory concerning the familiar person's
  occupation, personality, etc.

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Unusual views
Fear, anger
Perception of features of face (shape, size)
Stored representations of familiar faces
Knowledge about familiar people (occupation etc)
Specific names of people
Bruce and Young, 1986
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Evidence for the model

• Experimental evidence
• Familiarity decisions are faster than PIN
  decisions (Young et al., 1986b).
• Have you seen this face before versus is this an
  actor? YES or NO (button press).
• Therefore, access to Face Recognition Units must
  precede access to Person Identity Nodes
  (knowledge).

• Reaction times (RTs) to PIN decisions about faces
  are faster than face naming (Young et al. 1986).
• Is this an actor versus Is this John
  Malkovitch?
• Person identity knowledge is accessed before the
  stage of name information.

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Prosopagnosia

• An acquired inability to recognize familiar
  faces
• famous faces
• friends
• family
• own face in the mirror.

• Patients know when they are looking at a face,
  but they cannot say who the face belongs to.
• They rely on other non-facial cues for person
  identification e.g., gait, clothing.

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More evidence for the model

• Neuropsychological
• Prosopagnosia patients
• Dissociations between the recognition of familiar
  people (prosopagnosia) and lip reading in hearing
  impaired or deaf signers (Campbell et al. 1986).

• Mrs D cannot recognise faces but she can lip
  read.
• Mrs T can recognise faces but she cannot lip
  read.
• Impaired naming of faces can occur with intact
  access to biographical knowledge about a person.
• This is called anomia.

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Evidence against the model

• Implicit recognition of faces by prosopagnosic
  patients.
• PH could classify famous faces into their correct
  occupation even though he did not recognise the
  face.
• So PIN information can be accessed without
  conscious recognition of FRUs.

• De Haan et al (1991) reported a prosopagnosic who
  could match faces to the names of famous people
  correctly.
• However, she was unable to recall any
  biographical (PIN) information about the face.
• Is this an actor? DK
• So name generation can occur without first
  accessing the FRUs of a famous face.

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IAC model of face recognition

• Units within a pool are linked via inhibitory
  connections.
• There are excitatory connections between
  corresponding units in different pools.
• Links are bidirectional.

• Model is a sequential cascaded account.
• Information processing at one stage need not be
  complete before processing at the next level is
  initiated (c.f. Bruce et al., 1990).

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Impaired for PH
Intact for PH
Burton, Bruce Johnston, 1990
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Evaluation of IAC model

• Cognitive models of face recognition must
  explain
• Familiarity effects.
• Implicit processing by prosopagnosic patients.
• IAC model explains PHs access to PIN knowledge
  even though he cannot access FRU knowledge.

• Are representations of faces and their identities
  stored as a local units or as distributed units?
• The IAC model and the behavioural evidence
  suggests representations of faces are stored as
  distributed units.

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The fusiform gyrus and vision
Tools
Objects
Faces
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Summary

• Face recognition involves
• Physical information (shape, colour, form).
• Semantic information (biographical).
• Phonological information (names).
• Cognitive models of face recognition can explain
  familiarity effects on normal face recognition
  and implicit processing of faces in prosopagnosia.