UNIT 2.1

Selective Attention

2.1-1 How does selective attention direct our perceptions?

Selective Awareness: focusing conscious awareness on a particular stimulus

We pay attention to the things we think are important

  • Cock-tail Party Effect: ability to listen for only one voice in a sea of voices

Inattentional Blindness: failing to see visible objects when our attention is directed somewhere else

By manipulating our selective attention there our so many things we can fail to see

  • Change Blindness: failing to notice changes in our environment

Our selective attention directs our perceptions by filtering out irrelevant stimuli, which can lead to significant gaps in our awareness of the surrounding environment.

Expectations, Context, Motivation, and Emotion

2.1-2 How do our expectations, contexts, motivation and emotions influence our perceptions?

Bottom-up processing: analysis beginning with sensory receptors and working up to the brain’s integration of sensory info

top-down processing: info guided by higher level mental processes, as when we construct perceptions drawing on our experience & expectations

Perceptual set: a mental predisposition to perceive one thing and not another

  • expectations that influence perception

  • Cause individuals to perceive stimuli in a certain way based on what they expect or want to see

Schema: a collection of basic knowledge about of a concept or entity that serves as guide to perception, interpretation, imagination, or problem solving.

  • both are internal factors that filter our perceptions of the world

Two types of Schemas

Assimilation: interpreting one’s new experience in terms of ones existing schemas

Accommodation: adapting one’s current understanding to incorporate new info

Perceptual adaptation: the ability to adjust to changed in sensory input, including an artificially displaced or even inverted visual field.

Context: like the physical setting or social situation can create expectations that influence our perceptions

  • different cultures may cause people to view things differently

Motivation: motives that give us energy as we work toward a goal but can bias our interpretations of neutral stimuli, like context

  • a water bottle might seem closer to a thirsty person than it really is

Emotion: emotions can shove our perceptions in one direction or another

  • hearing cheerful music speeds up identification of happy emotion words

much of what we perceive comes not just from whats “out there” but aslo from whats behind our eyes and between our ears. Our experiences, assumptions, expectations and even our own context, motivation and emotions can shape and color our views of reality through top-down processing

Perceptual Organization

2.1-3 How did the Gestalt psychologists understand perceptual organization, and how do figure-ground and grouping principles contribute to our perceptions?

gestalt: an organized whole. gestalt psychologists emphasized our tendency to integrate new pieces of info into meaningful wholes

Figure-ground: to perceive objects as either the focus of attention (figure) or the background and seeing it as distinct from its surroundings

  • when you read words(figure) the white space is the background

Grouping: the perceptual tendency to organize stimuli into coherent groups and illustrates how the perceived whole differs from the sum of its parts

  • proximity: grouping nearby objects together (a row of dots perceived as a line)

  • similarity: grouping objects through similar characteristics (items that look alike)

  • closure: to fill in the gaps of an incomplete object into a complete whole object (brain fills in missing info to create a complete image)

Depth perception

2.1-4 How do we use binocular and monocular cues to see in three dimensions, and how do we perceive motion?

depth perception: the ability to see objects and the world in three dimensions although the images that strike the retina are two dimensional, allows us to judge distance and know how far away objects are

visual cliff: a lab device for testing depth perception on infants and young animals

Binocular cues: a depth cue that depends on the use of both eyes

  • convergence: the inward rotation of the eyes to focus on a nearby object

  • retinal disparity: the slight difference from the retinal images because of the distance between the two eyes. the greater the disparity(difference) between the two images the closer the objects.

Monocular cues: depth cues available to each eye separately

  • linear perspective: parallel lines seem to converge and meet toward a vanishing point as they recede into the distance

  • interposition(occlusion): when one object partially blocks our view of another, we perceive it as closer

  • relative size: causes us to perceive something as farther away because it looks smaller than an object in the foreground that we assume is similar size

  • relative clarity: Nearer objects are usually clearer in detail, whereas more distant objects are less distinct and appear blurry because more light passes through objects that are farther away.

  • texture gradient: when moving toward or away from an object changes our perception of its smoothness or texture

Apparent movement: when certain visual stimuli create the illusion of depth leading observers to interpret stationary objects as if they are moving in a specific direction. 

  • stroboscopic movement: a series of still images presented in rapid succession creates the illusion of continuous motion (motion pictures and animations)

  • phi phenomenon: the perception of movement created by rapidly presenting two or more stationary stimuli in succession (when 2+ adjacent lights rapidly blink on and off, we perceive the light as moving)

  • auto-kinetic effect: the illusory movement of a still spot of light in a dark room

Perceptual constancy

2.1-5 How do perceptual constancies help us construct meaningful perceptions?

perceptual constancy: perceiving objects as unchanging (having consistent color, brightness, shape, and size) even as illumination and retinal images change

  • color constancy: the tendency to perceive a familiar object as having the same color under different conditions of illumination. For example, a red apple will be perceived as red in well or poorly illuminated surroundings. (context governs our perceptions)

  • brightness constancy: the tendency to perceive a familiar object as having the same brightness under different conditions of illumination. For example, a piece of white paper has a similar brightness in daylight as it does at dusk, even though the energy it reflects may be quite different.

  • size constancy: Perceived size of an object remains constant despite changes in the size of the retinal image of that object.

  • shape constancy: Perceived shape of an object remains constant despite changes in the shape of the retinal image of that object.

Experience and Visual Perceptual

2.1-6 What does research on restored vision, sensory restriction, and perceptual adaptation reveal about the effects of experience on perception?

Perceptual adaptation: the ability to adjust to changed sensory input including an artificially displaced or inverted visual field