SENSATION, ATTENTION, PERCEPTION BLOCK 3: PART 1

what is perception? 1 pt

a function that involves the ability to intergrate sensory info from the outside world, complement it with prior sensations, assign meaning to it, and respond accordingly

three possible relationships that can occur in perception? 3 pts

1. stimulus-perception→ relates to the relationship between a physical stimulus an its perception e.g. minimal differences in the perception of one colour from another

2. stimulus-physiology→ relates to the relationship between the stimulation and activation of the nervous system e.g. bioelectrical activity of the cortex

3. physiology-perception→ relates to the relationship between the activation of the nervous system and the perception of the stimulus e.g. brain activity measured by EEG etc

factors influencing perception? 3 pts

1. personal factors

2. social factors

3. neurophysiological factors

4. perceptual organization

perception according to gestalt? 1 pt

perception is the result of organizational forces that dictate that the whole is greater than the sum of its part and rejects the idea that perception is merely the sum of simple element/sensations

principles of perceptual organization in gestalt psychology? 2 pts

1. unification- closure, proximity, similariy

2. constancy- size, shape, brightness

unification laws: pragnanz law? 3 pts

1. reality is organized or reduced to the simplest form possible

2. we naturally gravitate towards things that are simple, clear, and orderly because they feel inherently safer and require less processing time

3. when faced with complex shapes we tend to reorgnaize them into simpler components or a more straghtforward whole

unification laws: proximity law?

things that are near each other are grouped together

unification laws: similarity? 2 pts

1. similar things appear to be grouped together

2. our brain groups things that have common visual properties e.g. color or movement

unification laws: good continuation? 2 pts

1. points that when connect result in a straight/smoothly curving line are perceived as belonging together

2. in human visual perception elements of a global form are unified according to their continuity in a straight line or curved line allowing the perception of a form as a globality

unification laws: closure? 2 pts

1. individuals perceive objects as being a whole when they are not complete

2. our brains fill the visual gap of a global form with incomplete parts

unification laws: symmetry? 1 pt

the mind perceives objects as being symmetrical and forming around a center point

unification laws: common fate? 1 pt

things that are moving in the same direction appear to be grouped together

unification laws: common region? 1 pt

elements that are within the same region of space appear to be grouped together

unification laws: uniform connectedness? 1 pt

a connected region of visual properties e.g. lightness, texture, color etc is perceived as a single unit

unification laws: meaningfulness/familiarity? 1 pt

things that form patterns are familiar/meaningful are likely to be grouped together (pareidolias)

constancy: size constancy? 3 pts

1. reflects our tendancy to perceive an object as being the same size regardless of its distance from us

2. when we approach/get away from an object its size remains relatively the same

3. in human visual perception proximal size can increase/decrease but distal size remains the same

factors of size constancy? 4 pts

A. indirect perception

1. familiarity vs novelty- familiarity improves size constancy; novelty makes size constancy harder.

2. size distance scaling- the observer determines the distal size through size distance scaling resulting from the counterbalancing of out retinal image decreasing and perception of distance increasing

3. relative size- the observer considers the object’s size by comparing it with others in the visual field

B. direct perception

1. info regarding size constancy depends on the object’s affordances and the invariances in the optic array

constancy: shape constancy? 3 pts

1. regardless of changes to an object’s orientation e.g a door opening the object’s shape is perceived the same

2. the observer assesses the object’s degree of tilt and intergrates this info with the proximal image

3. preservation of form consistency only occurs if the observer can take into account the inclination or orientation of the object

constancy: lightness constancy? 2 pts

1. the amount of light reaching the eye from an object depends on the illumination (total amount of light striking the object’s surface) and the object’s reflectance (proportion of this light that the object reflects into our eyes)

2. our perception of an object’s lightness depends only on the object’s reflectance which remains stable no matter the illumination

limitations of gestalt approach? 4 pts

1. the laws are sometimes too general.vague

2. the laws describe only the initial stages of perceptual organization depending on the individual’s immediate experience

3. gestalt principles should have been referred to as heuristics instead of laws (a misnomer) because they are rules that provide best guess solutions to specific problems rather than making strong predictions

4. gestalt principles are heuristics that can sometimes lead to errors because our perceptual system is designed to operate quickly based on environmental stimuli

is gestalt approach a top-down processing or bottom-up processing approach? 1 pt

top-down processing

james gibson’s theory of direct perception (1950)? 1 pt

invariant info from the environment is directly perceived and the basis of perception lies in the characteristics of the environment rather than the organism → led to the ecological theory of perception

gibson’s ecological approach? 5 pts

1. states that perception is direct and that people obtain information from the environment without relying heavily on internal cognitive processes

2. emphasizes the perception of affordances, or action possibilities offered by the environment

3. the most appropriate way to describe a stimulus is in terms of optical patterns

4. info crucial for perception is generated by the observer’s movements (parallax)

5. the critical element of optical alignment is invariant info (constant info when the observer moves) that leads to direct perception

gibson’s perceptual invariances: optic flow? 6 pts

1. optic flow- pattern of visual movement that occurs across the retina as we move through the environment

2. the flow is more rapid near the moving observer and there is no flow at the destination towards which the observer is moving

3. gradient of flow- fast near the observer and slower farther away

4. gradient of flow provides info about the observer;s speed

5. absence of flow at the destination point is called the focus of expansion (FOE)

6. optic flow provides invariant info because it cocurs no matter where the observer is as long as they are moving

gibson’s perceptual invariances: texture gradients? 1 pt

texture changes as distance increases; texture appears finer in the distance than in the foreground and is another cue to perception that is visible to the observer (does nto need to be constructed)

gibson’s perceptual invariances: motion parallax? 3 pts

1. motion parallax is a type od depth perceptuion cue in which objects that are closer appear to move faster than objects that are further away

2. occurs when objects that are at different distances from us appear to move at rates that are different while we are moving

3. we judge an object’s distance based on how quickly an object moves; the closer the object the faster it appears to move and vice versa

gibson’s perceptual invariances: affordances? 2 pts

1. an affordance refers to the perceived and actual properties of an object determining how it can potentially be used e,g, a chair affords support and therefore affords sitting

2. affordances offer clear indications of how objects function; when someone perceives an affordance they understand what to do by looking at it

limitations of gibson’s approach limitation? 3 pts

1. even if the invariant environmental info is perceived directly we still need to make sense of it through out senses depending on the physical, psychological, physiological states

2. the combo of these states allows us to recognize the objects and its affordance

3. the concept of affordance is not wide enouogh to explain human perception and this theory does not allow us to understand perceptive illusions