cog and bio psych lecture 6 Flashcards
what is an object?
a thing you can see or touch that isn’t usually a living animal plant or person
Who created Gestalt psychology?
German scientists (Wertheimer, Koffka, Kohler) circa 1910
what does Gestalt mean?
whole
What does Gestalt psych suggest?
that perception could not be done by breaking it down into parts but by considering the whole experience
what are the Gestalt laws of perceptual organisation?
law of proximity, similarity, closure, good continuation and common fate.
What is the law of pragnanz?
the law of simplicitiy
What does the law of simplicity mean?
the percept you see should be the simplest interpretation of the scene
Evaluating the laws
not a near complete description of perceptual organisation
provide us some framework on how to separate figure from the ground
refer to image (world is complex)
refer to image (world is complex)
What is one of the most difficult task the visual system must perform?
object recognition
What are the two theories of object recognition?
image based models
structural based models
What is an image based model? (Poggio & Edelman (1990) Bulthoff & Edelman (1992) Ullman (1989) Riesenhuber & Poggio
(2000) )
specific views are stored and recogntion oerformance is based on generalisation from these
what do images based models envode
structured templates of viewpoint dependent representations
What does structural description model give? Biederman (1987), Hummel & Biederman (1992) Marr & Nishihara (1978), Leek, Reppa & Arguin (2005)
information about the 3D structure of an object extracted from a single view
What does Marr say?
object parts are rep’ed independently of their spatial configuration and viewpoint
What are objects represented by>
basic shape units called geons (check lecture 6 cog and bio)
what are geons?
defined by variations in a small number of basic parameters called non accidental properties (NAP)
what are NAP properties?
curvilinearity
parallelism
cotermination
symmetry
collinearity
what is curvilinearity?
curviness in the 2D imafe cuased by curve on object
what is parallelism?
lines in parallel in 2D object caused by parallel lines on an object
what is symmetry?
axis of symmetry in 2D imafe reflect the axis of symmetry on object
what is collinearity?
a straight lien in the 2D image is caused by straight line in an object
pictures in week 6 cog and bio pg 4
pictures in week 6 cog and bio pg 4
role of of view point generalisation
better accuracy at the learnt rather than interpolate viewpoints
argues for image based models
effects of stereo depth info
although not sig in all experiments, 3D viewing condition easier to perform
argues for structural description models
what is the canonical viewpoint?
image of an object that is the most representative
Experiment on C.V. by Palmer, Rosch and Chase in 1981
ppts shown views of an object and asked to rate how much each one looked like the objects they depict
scale 1 = very much like
7 = very unlike
results of this study
when presenting all viewpoints same frequency observers had preference for specific viewpoints
few viewpoints presented, recognition better for previously seen viewpoints
What is our visual system active in?
attempt’s to organise our perceptual input, happens without conscious effort
what is apophenia?
seeing faces in everyday objects
why is face recognition important to psychology
involves within cat discrim
- not is it a face but which face
- discrim between members of same category, discirm of patterns of same features e.g. eyes, mouth, nose
What does Devlin 1976 argue?
errors in face recog can have catastrophic consequences
EWT
is face recognition special Johnson and Morton (1991)?
new born babies preferentially view face from day 1 (9 minutes)
is face recognition special (Meltzoff and Moore, 1977)?
expression analysis seems to be innate - though we already accept that this is independent of recognition
what does the Featural hypothesis suggest? (Garner, 1978).
faces primarily remembered due to facial features
what does the configurational hypothesis suggest (Bartlett & Searcy, 1993; Diamond & Carey, 1986)?
places emphasis on the relationship amongst facial features
