Perception 1 part 2 (ObjectSceneAudioPart2) Flashcards
The the challenges of Object Perception
1) The stimulus on the receptor is AMBIGUOUS - reverse projection problem (the vase - face experiment) : an image on the retina can be caused by an infinite number of objects
2) objects can be PARTLY HIDDEN or blurred - occlusions and overlaps are common in the environment.
3) views look different from DIFFERENT VIEW POINTS
(- viewpoint invariance :the ability to recognise an object regardless of the viewpoint.
- This is a difficult task for computers to perform)
OBJECT-SPECIFICITY + VIEW-SPECIFICITY
Figure Ground Perception
Figure-ground segregation - determining what part of environment is the figure so that it “stands out” from the background
Properties of figure and ground
The figure is more “thinglike” and more MEMORABLE than ground.
The ground is more UNIFORM and extends behind figure.
The contour separating figure from ground belongs to the figure (BORDER OWNERSHIP)
Elements located in the lower part of displays (STANDING NOTIION)
Units that are symmetrical (ARRANGEMENT NOTION)
Elements that are small (SMALLER THAN BACKGROUND)
Units that are oriented vertically (GRAVITY NOTION)
Elements that have meaning (OBJECT CONCEPTS)
RUBIN ?
FACES - VASES PICTURE
MMMMTHINK rubin the vase cos he thinks its a lamp with a gene in it ……..Rubin!!!
FIGURE GROUND PERCEPTION key words to remember and trigger the factors.
Memorable Uniform Border ownership Standing Notion Arrangement Notion Smaller than background Gravity Notion Object Notion
VECERA et al 2002
Red green displayed horizontally and vertically,
participants asked which was the foreground
over 75% said the lower shape as the figure.
just over 50 said the left was the figure when they on the left and right
.
mmmm think vec (R) era, i.e. the era of the VCR and a picture of 2002 is being showed to participants and they re asked which is the foreground , the 20 or the 02 ? all looking on an old VCR
describe the two directions in information processing?
bottom up processing - the person registers sensory information
top down processing - built in biases that filter the incoming sensory information.
Object theories…..
conceptualise how we configure an object from its parts
AKA part - whole integration.
Viewer centred approach is how the object ………
Object centred is how it is ……..
Looks
Built
MARR + NISHIHARA 1978
Objects consist of Geometric Primatives
All shapes can be described as generalised CONES
Proportion of size of the ………. and the way they are linked determines the ……. …. ……. ……….
cones
identity of the object
GEONS
Objects are recognized by volumetric features called geons
Theory proposes there are 36 geons that combine to make all 3-D objects.
Geons include cylinders, rectangular solids, and pyramids (BIEDERMAN, 1987)
“THESE 36 GOENS were made by the man”
BY DER MAN
BIE DER MAN
GET IT!!!!!!!! IN 1987 JUST THINK OF A MASSIVE 87 BY SPIDERMAN AND HIS 36 GEONS
4 Principles of GEONS
VIEW-INVARIENT PROPERTIES- aspects of the object that remain visible from different viewpoints
NON-ACCIDENTAL PROPERTIES - properties of edges in the retinal image that correspond with the 3-D environment
DISCRIMINABILITY - the ability to distinguish geons from one another
PRINCIPLE OF COMPONENTIAL RECOVERY - the ability to recognize an object if we can identify its geons
VIEW-INVARIENT PROPERTIES-
Each geon can be distinguished from the others from almost any viewpoints except for “accidents” at highly restricted angles in which one geon projects an image that could be a different geon, as, for example, when an end-on view of a cylinder can be a sphere or circle. Objects represented as an arrangement of geons would, similarly, be viewpoint invariant.
NON-ACCIDENTAL PROPERTIES -
Stability or resistance to visual noise: Because the geons are simple they are readily supported by the Gestalt property of smooth continuation, rendering their identification robust to partial occlusion and degradation by visual noise as, for example, when a cylinder might be viewed behind a bush.
DISCRIMINABILITY -
the ability to distinguish geons from one another
PRINCIPLE OF COMPONENTIAL RECOVERY -
the ability to recognize an object if we can identify its geons
Junctions
Junctions are crucial meetings of contours in object representations
The names of the junctions mostly represent literally the letter shapes
There a L-Junctions, T-Junctions, Y-Junctions and A(arrow)-Junctions according to HUFFMAN (1971) (see also Willats, 1997)
HUFFMAN 1971
Junctions are crucial meetings of contours in object representations
The names of the junctions mostly represent literally the letter shapes
There a L-Junctions, T-Junctions, Y-Junctions and A(arrow)-Junctions according to HUFFMAN (1971) (see also Willats, 1997)
mmmmthink he got in a HUFF MAN cos he had so many junctions to differentiate between.
Object Edge Detection
Amount of NECCESSARY EDGE PROCESSING is investigated with contour-deleted pictures (BIEDERMAN, 1985)
Partial contour deletion versus geon deletion: Contour junctions were essential for recognition, but complete, continuous lines were not (remember that we do complete figures and lines with our ‘Gestalt’ perception abilities)
A scene is acted ……..
An object is acted ……
Within
Upon
a scene contains
Background elements
Objects Organized ini meaningful ways with each other and the background
texture changes
Experiment by TONG et al (1998)
Picture of a house shown to one eye and a face to another
Participants pushed button to indicate perception.
fMRI showed an alternating increase in activity in
Parahippocampal place area for the house
Fusiform face area for the face
mmmmmthink Its all gone a bit pete tong!!! dennis pennis is clubbing at his house with an fMRI scanner - he’s invites the fusiform and the fusiform lights up when he sees a face and the parahippocampal for a house ( think a paratrooper hippo coming down on a house that dennis is clubbing in
Its all Gone a bit PETE TONG!!!!!! with the fMRI scanner too
Physical Regularities in the Environment
Physical regularities are regularly occurring physical properties
OBLIQUE EFFECT - people perceive horizontals and vertical more easily than other orientations
UNIFORM CONNECTEDNESS - objects are defined by areas of the same color or texture
LIGHT FROM ABOVE HEURISTIC - light in natural environment comes from above us
OBLIQUE EFFECT -
people perceive horizontals and vertical more easily than other orientations
UNIFORM CONNECTEDNESS -
objects are defined by areas of the same color or texture
LIGHT FROM ABOVE HEURISTIC -
light in natural environment comes from above us
Semantic Regularities in the Environment
PALMER (1975) Object Identification in Scenes
Observers saw a context scene flashed briefly, followed by a target picture.
Results showed that:
Targets congruent with the context were identified 80% of the time .
Targets that were incongruent were only identified 40% of the time.
mmmmthink PALMER showed the different scenes with the congruent and incongruent objects all drawn on the PALM of his hand!!! what a nutter. he opened and closed his hand super quick so they only had a moment. and when the scene of the kitchen flashed in his Palm people
A scene not only has physical regularities , it also has …………. …………..
semantic regularities
Brain Modules Involved in Perceiving Faces
Fusiform face area (FFA) - responds only to faces
Amygdala (AG) - activated by emotional aspects of faces
Superior temporal sulcus (STS) - responds to where the person is looking and to mouth movements
Frontal Cortex (FC) - activated when evaluating facial attractiveness
Fusiform face area (FFA) -
responds only to FACES
Amygdala (AG) -
activated by EMOTIONAL aspects of faces
Superior temporal sulcus (STS) -
responds to WHERE the person is looking and to MOUTH MOVEMENTS
Frontal Cortex (FC) -
activated when evaluating facial ATTRACTIVENESS
GRILL SPECTOR et al. (2004):
Identifying an Object: Is that Harrison Ford?
participants were shown a picture then asked what they had seen
All stimuli were shown for 50 ms, 60 pictures of each type were presented.
correct facial recognition required the most effort compared to most other responses
MMMMTHINK doing this flashing image test was a charr Grilled Ghost a Grill spector if you will!!! the picture of Harrison ford created the greatest Fmri signal
