Perceptual ProcessesCognitive Psychology Spring, 2014Review for Exam 1Exam 1 covers chapters 1, 2, 3, & 4. Skip section on speech perception in Chapter 2.Perceptual Processes- Theories of Object Recognition, focus on Recognition by Components model (geon theory).o Two theories of object recognition1. Recognition by components : theory by Biederman that any given view of an object can be represented as an arrangement of simple 3-D shapes called geons; 36 geons differ by edges, symmetry, sweep, axis, and comparative relations to other geons.2. Feature Analysis theory : visual system is composed of a small number of characteristics or components called distinctive features; problem: featuresin nature are more complex- Distinction between Top-down and bottom up processingo Bottom up : environment analyzed into visual features, build up into objectso Top down : expectations and knowledge guides perception - Neural network, also known as connectionist, or parallel distributed processing PDP theory of perceiving features. o Connectionist model of processing/ PDP : Units are interconnected and can excite/inhibit other units; theory that the cognitive processes can be explained by activation flowing through networks that link together nodes. Every new event changes the strength of connections among relevant units by altering the connection weightso word superiority effect : when a reader is presented with a word, each letter in parallel will either stimulate or inhibit different feature detectors which will then stimulate or inhibit different letter detectors, which will finally stimulate or inhibit different word detectors (features -> letters -> words)- Change blindness.and inattentional blindness. o Change blindness : changes in visual scenes are arranged to occur simultaneously with some kind of extraneous, brief disruption in visual continuity; we fail to detect a change in an object or scene due to overuse of top-down processing (ex: screen flickers between two presentations of scene, a major change between the two must be detected)o Inattentional blindness : when we are paying attention to some events in a scene, we may fail to notice when an unexpected but completely visible objects suddenlyappears (ex: door study- an unnoticed gorilla walking through basketball players);more likely when the primary task is cognitively demanding. - Separate brain systems for perceiving object identity (what) and where it is (or howto act on it). o Temporal lobe = object recognition (What)1. Conscious systemo Parietal lobe = action to location (how/where)1. Unconscious system- Research on the “how” system not being susceptible to certain visual illusions.Attention: Capacity and Selection.- Attention enhances processing, we control allocation of attention across visual displays.- Measuring the Attention requirements or demands of tasks by using secondary reaction time to a tone or visual probe, the limited capacity of attention (Posner & Bois experiment).o Posner and Boies Warning Signal1. Primary task: letter matchingo First letter, then Second letter, match or not? (e.g., a then A“yes” C then j “no”)2. Secondary task: auditory tone detectiono tone presented a different points relative to letter stimuli, press button as fast as possible results: tone had no effect- Posner experiment with cue to attend to left or attend to righto speeds ability to respond to target square in place you are attendingo slows response to target in unexpected placeo Shows orienting to location- Attention and eye movement usually goes togethero eye movements/saccades, but attention can move w/out eyes- Dichotic listening studies of selective attention, Stroop effect also requires selection, as does flanker task.o Dichotic Listening Study : participants were asked to listen to both messages at the same time and repeat what they heard conclusion: you can only pay attention to the message in one ear (channel) at a time - the message in the other ear is lost- could be explained by the short-term memory storeo Stroop effect : subjects are told to press a left key or a right key depending on the color of the stimulus the color word is irrelevant- can be either consistent (e.g. “blue” written in blue ink) or inconsistent (e.g. “green” written in blue ink) with the color Responses are faster and more accurate for consistent stimuli than for inconsistent stimuli.o Flanker task : subjects are shown a string of letters on a screen told to press a left key or a right key depending on what letter appears in the center of the screen (target letter) surrounding flanker letters are irrelevant- can be either consistent (“HHH”) or inconsistent (“SHS”) with the target Responses are faster and more accurate for consistent stimuli than for inconsistent stimuli- Triesman and Gelade’s feature integration theory. o Feature Integration Theory : theory that suggests that we have feature maps (shape, color, size) that are loaded without attention There are two forms of vision:1. Pre-attentive Visiono Uses distributed attentiono object is analyzed for details such as shape, color, orientationo occurs early in perceptual processing2. Attentive Visiono Uses focused attentiono conjunction searcho individual features of an object combine in order to perceive the whole object- Difference between conjunctive and disjunctive searches in visual search tasks. o Conjunctive search : search in which person must bind two features which requires attention and takes longer; serial processingo Disjunctive search : search in which items have at least one set of similar characteristics; features should "pop out" during search and should be able to form illusory conjunctions; parallel processing- Automatic versus controlled attention, and the acquisition of automaticity in visual search experiments of Schneider and Shiffrin (search for J or T among displays or letter, or search for different letters from trial to trial.) o Automatic attention : parallel processing, fast, not attention demanding, produces interference because it is involuntary, does not require capacityo Controlled attention : serial processing, slow, attention demanding, consciously controlled, does not produce interferenceo Schneider and Shiffrin search for J or T among displays or letter, or search for different letters from trial to trial RT longer for varied mapping vs consistent -
View Full Document
Unlocking...