Module 2 - Sensation & Perception Flashcards
signal detection theory
detection of a stimulus involves decision and sensory processes
liberal vs conservative bias
liberal: more likely to say “yes, signal present”
conservative: more likely to say “no, signal absent”
types of visual search
- feature search (one-dimensional, preattentive stage)
- conjunctive search (multi-dimensional, focused attention stage)
what do the Ganzfeld Experiments study?
study sensory adaptation
what are the findings from the Ganzfeld Experiments?
- sensory receptors are sensitive to change
- in a constant visual field, eventually perception fades to grey
- some people experience hallucinations
what are the types of photoreceptors?
- rods (sensitive to light/dark)
- cones (sensitive to colour)
- ganglion cells (sensitive to blue wavelengths)
optic ataxia
person can’t use visuospatial information to guide their movements
hemispatial/contralateral neglect
patient is unaware of the contralesional half of space
akinetopsia
inability to perceive motion
apraxia
inability to produce discretionary or volitional movement in the absence of muscular disorders
apperceptive visual agnosia
impaired object recognition
associative visual agnosia
impaired object identification
theory of direct perception (Gibson)
- the environment usually provides enough context to interpret everything we are seeing
- we don’t need higher level cognitive processes to understand and interpret
template theories
- we have stored templates for patterns we might encounter
- match the patterns we’re seeing to a template to identify objects and interpret what we see
feature matching theories
- we identify objects by matching them to sets of features stored in memory
- inexact, fuzzy matches
in the Navon Task, what occurs when local features are tightly organized?
- identification of global features is not slowed by incongruent local features
- identification of local features is slowed by incongruent global features
in the Navon Task, what occurs when local features are loosely organizes?
- identification of global features is slowed by incongruent local features
- identification of local features is not slowed by incongruent global features
what are feature detectors?
neurons that respond selectively to very specific features of more complex stimuli (orientation, movement, edges, colour)
feature integration theory
preattentive stage: feature detectors gather information about colours, shape, movement
focused attention stage: combining features of an object requires attention
bottom-up processing
- helps us recognize new or unfamiliar objects
- examining in detail
top-down processing
- reducing workload
- quick judgements about vague stimuli
