CHAPTER 5 - PERCEPTION

Perception – the process through which sensations are interpreted, using knowledge and understanding of the world, so that they become meaningful experiences


APPROACHES TO PERCEPTION

* Computational – determine the _____________ needed to solve perceptual problems



* Constructional – interested in how _____________ and ____________, based on past experiences, affect perception



* Ecological – perceptual experience is due directly to the ___________ contained in the __________ in the environment



HOW DO PSYCHOLOGISTS MEASURE PEOPLE’S PERCEPTION?

Psychophysics – study the relationship between physical energy in the environment and our psychological experience of that energy


ABSOLUTE THRESHOLD – MINIMUM DETECTABLE AMOUNT OF A SENSE

* Addresses the following question: how much stimulus energy is needed to trigger a conscious perceptual experience?

o Vision = candle flame seen at 30 miles on clear night
o Hearing = tick of watch under quiet conditions at 20 ft
o Taste = one tsp of sugar in 2 gallons of water


* Not really an all-or-none phenomenon 

o If truly “absolute”, detection accuracy would jump from 0 to 100 percent at exact level that constitutes your _____________



* Too weak to evoke awareness = subliminal stimulus

o Expectations


o Self-fulfilling prophecy


o Emotion & judgment


* Falls above the threshold = supraliminal stimulus


SIGNAL DETECTION THEORY

* A mathematical model of factors that determine how people decide to respond when asked to detect faint stimuli (e.g., airport security)

* Even when stimuli (signals) are absent, people will experience perceptual stimulation = noise

* How do people differentiate noise from signals?

o 2 factors:

* Sensitivity – 



* Response criterion –



JUST NOTICEABLE DIFFERENCE (JND) – MINIMUM DETECTABLE DIFFERENCE BETWEEN TWO STIMULI 

* Weber’s Law –


o JND = KI, where K is the constant for a particular sense, and I is the intensity of the stimulus 

* Magnitude Estimation

o Fechner’s Law –



o Steven’s Power Law –



PRINCIPLE OF PERCEPTUAL ORGANIZATION

* Perceptual organization – task performed by the perceptual system to determine what edges and other stimuli go together to form an object

* Basic Principles

o Figure-ground processing – 




o Grouping – how do certain parts of the world become the figure and others the ground?

* Proximity -

* Similarity -

* Continuity -

* Closure -

* Common Fate -

* Synchrony -

* Common Region - 

* Connectedness -


o Likelihood principle – tendency to perceive objects in the way that experience tells us is the _________________ physical arrangement


o Simplicity principle - organize elements to make simplest possible perception


PERCEPTION OF LOCATION AND DISTANCE

* Depth Perception (Distance)

o Structure and position of our eyes

o Monocular depth cues

* Accommodation –


* ________________ to focus on closer objects

* ________________ to focus on more distant objects

o Binocular depth cues

* Convergence –


* Closer away --> more convergence

* Farther away --> less convergence

* Binocular disparity –


* Some important depth cues from the environment

* Interposition – close objects block view of far objects

* Relative size – larger image perceived to be closer

* Texture gradient – texture less detailed as distance increases

* Linear perspective – parallel lines converge toward single point

* Motion parallax – speed of moving objects near and far seem different

* Clarity, Color, Shadows


PERCEPTION OF MOTION

* We use cues from the changes in the retinal images across the entire visual field, called optical flow

* Looming – 


* Stroboscopic motion – 



RECOGNIZING THE PERCEPTUAL WORLD

* Bottom-up processing





* Top-down processing 

o Schemas – mental representations of what we know and have come to expect of the world



* Parallel distributed processing models – units in network operate in parallel (simultaneously)


ATTENTION 

* Process of directing and focusing certain psychological resources to enhance perception, performance, and mental experience

* Functions of Attention

o __________ our sensory and perceptual systems toward stimuli

o __________ specific info for further processing

o __________ the mental energy required to do that processing

o __________ the flow of resources necessary for performing a task or coordinating several tasks at once


* Characteristics of Attention

o Improves mental processing

o Takes effort

o Resources are limited


* Orienting Attention

o Overt -

o Covert -



* Allocating Attention

o Voluntary control -


o Involuntary control -


* Capturing Attention

o Selective - 


o Divided Attention –


o Inattentional blindness - 



ADDITIONAL LEARNING OBJECTIVES

* Discuss how auditory scene analysis organizes our perception of sounds. (see Auditory Scene Analysis)

* Define perceptual constancy. Give examples of size, shape, and brightness constancy. (see Perceptual Constancy)

* Describe an infant’s perceptual abilities. (see Linkages:  Perception and Human Development)

* Explain parallel processing. (see Attention and Automatic Processing)

* Describe the influence of perceptual studies on the development of aviation and computer displays. (see Applications of Research on Perception)