Perception Flashcards
Apperceptive Agnosia
Impairment due to deficits in perceptual processing.
- dorsal route
- view dependent
- bottom up processing
- where how
Associative Agnosia -
Perception in tact except difficulties in accessing relevant knowledge about objects from memory.
- Oliver Saks glove example
- ventral
- view invariant - top down
- what
Object Agnosia
Impaired object recognition but intact facial recognition
Structural encoding
Various representations or descriptions of faces
Expression analysis
An emotional state can be inferred from facial features
Facial speech analysis
Speech perception can be aided by observing lip movements
Directed visual processing
Special facial info may be processed selectively
Face recognition units
Structural info about known faces
Person identity nodes
Information about individuals (eg occupation, interests)
Cog system
Contains additional info (eg actors tend to have attractive faces) and influences which other components receive attention
Support
Double dissociation - across patients w an impairment on either face recognition or expression identification
- In a study, participants never reported putting a name to a face while knowing nothing else about that person
Visual Agnosia
Impairment of visual object recognition despite otherwise preserved visual abilities
Limitations
The model omits the first stage of processing (i.e., detecting that they‘re looking at a face)
Facial identity and facial expression may not be entirely independent
There may be multiple systems for facial expressions
The emotional system may play a far more integral role here
Posed expressions
lack congruent feeling (i.e. happiness)
- lack congruent feeling (i.e. happiness)
Spontaneous facial expressions
are known as “Duchenne” expressions.
Expressed with congruent feeling (i.e. feeling happy and smiling)
Uses the cingulate and basal ganglia.
Visual mental imagery
occurs when a visual STM representation is present but the stimulus is not actually being viewed
Visual imagery is accompanied by the experience of “seeing with the mind‘s eye”
Evidence of Interference
Baddeley and Andrade (2000)
Since visual imagery and spatial tapping are assumed to share the visual buffer, doing both simultaneously should impair performance
Gibson - Direct Perception
Suggested that perceptual information is used primarily in the organisation of action
Held that perception and action are closely intertwined
One influences the other without any need for complex cognitive processing
Took an ecological approach in this direct theory of perception
Optic Flow
Optic flow field as a pilot comes in to land, with the focus of expansion in the middle.
Affordances
Potential uses of objects (graspable v non-graspable)
Perceived directly
Participants are quicker to make grasping movements to objects that can be grasped
Strengths
Emphasized the interaction between perception and action
Captured the DORSAL vision-for-action system before it became common
Limitations
Processes involved in perception are much more complicated than implied by Gibson
Largely ignored the vision-for-perception (VENTRAL) system
Does not fully capture all the relevant sources of information
Glover
Planning-Control Model
Planning System
Mostly used before initiation of movement
Selects an appropriate target
Decides how the object will be grasped
Determines the timing of the movement
Uses both spatial and non-spatial information
Relatively slow
Planning depends on:
A visual representation located in the inferior parietal lobe
Motor processes in the frontal lobes and basal ganglia
Control System
Used after the planning system to ensure that movements are accurate
Influenced by the target object‘s spatial characteristics
Relatively fast
Control depends on:
A visual representation located in the superior parietal lobe
Motor processes in the cerebellum
The model is supported in several ways by many experimental findings
It is probable that the two systems interact in very complex ways in performing many kinds of actions
Monkeys
Mirror Neuron System
Formed of neurons activated when animals perform an action and when they observe another performing the same action
Facilitates imitation and understanding others‘ actions
Area F5 and superior temporal sulcus in monkeys
Humans
Mirror Neuron System
Regions that respond similarly to performing an action or watching others perform it:
Ventral premotor cortex
Anterior intraparietal cortex
Superior intraparietal cortex
However, these are entire areas, NOT neurons
The human mirror neuron system has yet to be detected on the neuronal level
Understanding Intentions
Conditions
Intention
Display: 1. Drinking out of a cup 2. Washing a cup
Action
Display: Hands grasping the cup as above, but w/o the context that might determine the intention
Content
Display: Same contexts as the intention condition but no grasping
Results
More activity was observed in brain areas forming part of the mirror neuron sys. In the intention vs. action condition
Change blindness
The surprising failure to detect a substantial visual change
Left vs. right hemisphere processing of perception
LEFT
DETAILS Verbal Analytic High spatial frequency Cognitive appreciation of emotions rational/stable
Left vs. right hemisphere processing of perception (RIGHT)
GESTALT Visuospatial/Perceptual Holistic/Syncretic Low spatial frequency Emotions as feelings
Vision for Perception Issue
Visual Agnosia: can see but cannot recognize or interpret visual information, due to a disorder in the parietal lobes.
Ventral Pathway lesion
Vision for Action Issue
Optic Ataxia (Bálint syndrome): restriction of visual attention to single objects and a paucity of spontaneous eye movements. Bálint noted inaccurate reaching of the man's right hand Dorsal Pathway lesion
VENTRAL
Object perception (what?) form and color processing Vision-for-perception allocentric perception is more based on object in environment; not self viewpoint invariant usually conscious; fast
DORSAL
motion processing
vision-for-action
egocentric
perception is based on orientation of viewer’s body
viewpoint dependent (orientation is important)
usually unconscious (don’t think how to reach for something)
