Object Recognition

Question 1

what is object recognition?

Answer 1

processes involved in identifying objects in the visual field

Question 2

what is mental chronometry?

Answer 2

the time course of a cognitive process

Question 3

Donder’s simple reaction time is …

Answer 3

is the fastest time possible to make a response after seeing the stimulus

Question 4

Donder’s choice reaction time is …

Answer 4

the time to push one of two buttons in response to a stimulus

Question 5

The difference between both of Donder’s reaction times shows what?

Answer 5

it reveals how long it takes to make a response

Question 6

What are the two key attentional systems involved in object recognition?

Answer 6

the ventral system

the dorsal system

Question 7

What is Marr’s computational theory

Answer 7

it describes different representations that are constructed in object recognition

1) grey level
2) primal sketch
3) 2.5 sketch
4) 3-D model representations

Question 8

In Marr’s computational theory what is grey level?

Answer 8

it is the first representation of the stimulus constructed

it compares the intensity of light across the retina, in order to identify edges, bars and terminations (known as place tokens)

Question 9

In Marr’s computational theory what is raw primal sketch?

Answer 9

it is the second representation of the stimulus which is reconstructed

it groups place tokens into patterns. This grouping is based on spatial pattern, size4 and density of the reoccurring images

Question 10

In Marr’s computational theory what is 2.5 sketch?

Answer 10

it is the third representation of the stimulus reconstruction

it is a viewer centred construction, vectors have been attached to the edges to indicate orientation

Question 11

In Marr’s computational theory what is the 3-D model

Answer 11

it is the fourth representation of the reconstructed stimulus

it allows the the viewer to imagine objects in a rotated position, the observer can recognise the object from different perspectives

Question 12

Summary of Marr’s approach…

Answer 12

object recognition is a computational process

it is a bottom up approach, that does not consider top-down and bottom up processing working in parallel

Question 13

Biederman’s recognition by components theory (RBC)

Answer 13

Objects are comprised of basic shapes known as geons

there are 36 geons and these can be combined in different ways

allowing us to recognise objects

Question 14

The steps of Biederman’s object recognition ..

Answer 14

1) edge extraction provides a line drawing of the object
2) segmenting a visual object into parts
3) deciding which edge information can be invariant depending on angle
4) geons constructed from these invariant properties
5) compare neon construction with object representations stored in LTM

Question 15

Summary of Biederman’s (geon) components theory

Answer 15

it emphasises bottom-up processing

object recognition is viewer invariant (objects can be recognised from all angles)

Question 16

evidence for biedermans component theory

Answer 16

Biederman (1987)

participants were presented with degraded lone drawings

if concavities (corners/junctions) were missing objects were harder to recognise

Question 17

Evidence for Bierderman’s Geons …

Answer 17

asked observers to decide whether objects presented in quick succession had the same name

when a neon was changed the task performance worsened

Question 18

Biederman’s problem of viewpoint invariant recognition …

Answer 18

viewpoint invariance occurs with familiar objects, however, viewpoint dependence is needed for novel objects

Question 19

Evidence that novelty is viewer dependent …

Answer 19

participants spent 7 hours learning to identify grebes

two grebes were then presented in quick succession and the observer had to decide whether they were the same or not despite the orientation changing

they found that the time taken to identify grebes increased as the orientation difference also increased

Question 20

new theories think object recognition is both invariant and dependent, but when are these viewpoints used?

Answer 20

invariant = categorisation

dependent = identification

Question 21

Does complexity influence viewer perspective?

Answer 21

Vanrie et al (2002) argued that complexity influenced whether object recognition was invariant or dependent

Question 22

what area of the brain is involved in object recognition?

Answer 22

inferotemporal cortex there are some neurons that have high invariance and others have low invariance

different regions of the infernotemporal cortex is specialised for different categories (e.g faces/places)

Question 23

what did neuroscience find out about the processing of object recognition?

Answer 23

found evidence for ventral bottom up processing but also that the dorsal stream (top down processes) are involved.

*** visual system has forward and backward projecting neurons

Question 24

evidence for top down processing …

Answer 24

ambiguous figures having two interpretations

when you prime a particular bias more likely to see that bias in the figure

Question 25

neuroscience evidence for top down processing …

Answer 25

when you mask drawings, the orbitofrontal cortex is activated first before the recognition pathway is activated