Qs: Adam has been diagnosed as suffering from prosopagnosia. First comment on the role
of the fusiform gyrus in facial recognition, then describe how prosopagnosia will affect
Adam’s visual perception and, in turn, his tasks of daily living.
Ans: the fusiform gyrus known as the fusiform gyrus of the inferior temporal cortex
especially in the right hemisphere responds strongly to faces than anything else and an area
close to this face area responds more strongly to bodies clearly face recognition depends on
the fusiform gyrus especially in the right hemisphere.
The Fusiform gyrus responds strongly to a face viewed from any angle as well as lines of
drawing and anything else that looks like a face. Neurons in that area also respond selectively
to complex aspects of faces such as whether a face appears to be male or female.
The ability to recognise faces correlates strongly with the strength of connections between the
occipital face area and the fusiform gyrus, people with stronger connections learn to
recognise faces easily and those with fewer connections have more trouble. People with
severe problems either because of brain damage or because they developed fewer connections
are said to have prosopagnosia, people with prosopagnosia have a visual problem of realising
faces.
When a person with prosopagnosia looks at a face they can describe, a few features of the
face but they cannot identify the person. So in the case of Adam he will continue to lead a
normal life and recognise other objects because prosopagnosia affects face recognition or the
greater need to discriminate visually and similar members of a single category in face
recognition compared to object recognition.
Adam will only be affected in his inability to recognise faces because prosopagnosia is an
impairment of a specialised form of visual recognition that is necessary for facial recognition
and it is not necessary for recognition of common objects, he may also be unable to recognise
his closest family members by vision alone.
, Some anecdotes tell of patients who confuse their reflection in a mirror for another person, so
it is possible that Adam, may no longer recognise his reflection, he may also find it difficult
to differentiate people’s genders and he may not be able to describe nor notice faces of
famous people, various studies mentioned incidents where patients were shown famous faces
but could not tell who those faces belonged to.
A female patient who also had prosopagnosia because of damage in the fusiform gyrus could
not differentiate between people’s genders she only knew females had a bust and that is how
she distinguished women from men.
Qs: Describe three main theories of colour perception and explain what each contributes to
our understanding of the subject
NB: Colour constancy/colour perception: The ability to recognise colours despite changes in
lighting
Ans: The three main theories of colour perception are namely: The Retinex theory;
Opponent- process theory and the Trichromatic (Young Helmholtz theory).
The Retinex theory: Is a combination of the words retina and cortex; the cortex compares
information from various parts of the retina to determine the brightness and colour for each
area, the brightness of an object is perceived by being compared to other objects.
The Trichromatic (Young Helmholtz theory): According to the theory people perceive colour
through the relative rate of response and three kinds of cones, each one maximally sensitive
to a different set of wavelengths, Helmholtz decided on the number three (Trichromatic)
because he found that people could match any colour by mixing appropriate amounts of just
three wavelengths, therefore, he concluded that three kinds of receptors are sufficient to
account for human colour vision, we discriminate among wavelengths by the ratio of activity
across the three types of cones, this ratio of responses among the three cones determines a
perception of yellow-green.
of the fusiform gyrus in facial recognition, then describe how prosopagnosia will affect
Adam’s visual perception and, in turn, his tasks of daily living.
Ans: the fusiform gyrus known as the fusiform gyrus of the inferior temporal cortex
especially in the right hemisphere responds strongly to faces than anything else and an area
close to this face area responds more strongly to bodies clearly face recognition depends on
the fusiform gyrus especially in the right hemisphere.
The Fusiform gyrus responds strongly to a face viewed from any angle as well as lines of
drawing and anything else that looks like a face. Neurons in that area also respond selectively
to complex aspects of faces such as whether a face appears to be male or female.
The ability to recognise faces correlates strongly with the strength of connections between the
occipital face area and the fusiform gyrus, people with stronger connections learn to
recognise faces easily and those with fewer connections have more trouble. People with
severe problems either because of brain damage or because they developed fewer connections
are said to have prosopagnosia, people with prosopagnosia have a visual problem of realising
faces.
When a person with prosopagnosia looks at a face they can describe, a few features of the
face but they cannot identify the person. So in the case of Adam he will continue to lead a
normal life and recognise other objects because prosopagnosia affects face recognition or the
greater need to discriminate visually and similar members of a single category in face
recognition compared to object recognition.
Adam will only be affected in his inability to recognise faces because prosopagnosia is an
impairment of a specialised form of visual recognition that is necessary for facial recognition
and it is not necessary for recognition of common objects, he may also be unable to recognise
his closest family members by vision alone.
, Some anecdotes tell of patients who confuse their reflection in a mirror for another person, so
it is possible that Adam, may no longer recognise his reflection, he may also find it difficult
to differentiate people’s genders and he may not be able to describe nor notice faces of
famous people, various studies mentioned incidents where patients were shown famous faces
but could not tell who those faces belonged to.
A female patient who also had prosopagnosia because of damage in the fusiform gyrus could
not differentiate between people’s genders she only knew females had a bust and that is how
she distinguished women from men.
Qs: Describe three main theories of colour perception and explain what each contributes to
our understanding of the subject
NB: Colour constancy/colour perception: The ability to recognise colours despite changes in
lighting
Ans: The three main theories of colour perception are namely: The Retinex theory;
Opponent- process theory and the Trichromatic (Young Helmholtz theory).
The Retinex theory: Is a combination of the words retina and cortex; the cortex compares
information from various parts of the retina to determine the brightness and colour for each
area, the brightness of an object is perceived by being compared to other objects.
The Trichromatic (Young Helmholtz theory): According to the theory people perceive colour
through the relative rate of response and three kinds of cones, each one maximally sensitive
to a different set of wavelengths, Helmholtz decided on the number three (Trichromatic)
because he found that people could match any colour by mixing appropriate amounts of just
three wavelengths, therefore, he concluded that three kinds of receptors are sufficient to
account for human colour vision, we discriminate among wavelengths by the ratio of activity
across the three types of cones, this ratio of responses among the three cones determines a
perception of yellow-green.
