In depth lecture notes about concept formation and categorisation/brain and cognition, may also contain diagrams and references- easy to understand layout great revision/exam prep
WEEK 6 BRAIN AND COGNITION– concept formation and categorisation
We need concepts to understand what is happening around us – without perception, object
recognition and categorisation we would be unable to interact meaningfully with the world. This
allows us to plan our actions.
OBJECT RECOGNITION- inferotemporal neurons sometimes fire in response to a particular object-
e.g. recognising a car from different angles
We can distinguish between individual exemplars- DISCRIMINATE between different forms of the
same stimuli. Yet we can also group them together and recognise they are of the same category
despite variation- GENERALISATION.
OBJECT CONSTANCY- consistently categorising objects even though the same object appears in so
many variances so when we re-encounter it doesn’t appear differently. Size, colour, occlusion (part
of an object hidden) and position as well as plane rotations and depth rotations are all
transformations that we can cope with.
Summary – the visual system must recognise familiar categories of objects whilst ignoring irrelevant
variation in the input that we perceive which may make objects look different from one instance to
the next. This is crucial as it lets us access the same semantic info (general knowledge about the
world- e.g. where would you find a stapler) whatever view of the object we see.
DEFINITIONS------
Concept - a mental representation of a class of things
(a type, eg "dog"; words refer to concepts) - the basis of our semantic knowledge
Category - the set of things that belongs to the concept class
(eg every actual dog that exists in the world belongs to the dog category)
Exemplar - one of the set of things in a category
(eg my own pet dog, Smudge)
Attribute (or feature or property or characteristic) - something which can be true or false of a particular thing (an exemplar) or of a
class of things (category)
(eg the thing or class of things is red, or expensive, or angry, or alive)
Typicality - either the distance in representational space of an exemplar to the category prototype or the average distance of an exemplar
to all other exemplars from the same category
Similarity - the distance in representational space between either two exemplars or two categories
TYPES OF CATEGORIES-
Natural- categories in the natural world (e.g. a giraffe, pebble)
Artefact- made by humans to serve a function (e.g. hammer, chair)
Nominal/ ad hoc- things sharing a characteristic/feature (e.g. yellow foods/thing we take on holiday)
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