notes923.doc

Exam breakdown (# of questions): History of psychology ? 5 Behaviorist findings ? 5 Research methods ? 5 Low-level vision ? 5 High-level vision ? 8 Attention, limited ? 5 Attention, selective ? 7 SELECTIVE ATTENTION Attention must be selective because it is limited If attention is on the wrong subject? Sometimes you must switch, sometimes you must search, ALWAYS you must evaluate Mike Posner: attention is like a ?spotlight? that enhances perceptual processing for a given area of space This is an important metaphor, but not completely true. Switching [arrow, cue trials ? test for moving, engaging, and disengaging using cues and ?go? commands] Neural evidence suggests that damage to different parts of the brain support three separate processes: disengaging, moving, and engaging. -if disengaging function is damaged (posterior parietal cortex), subjects have serious difficulty reacting to invalid trials because it is very hard for them to disengage (for valid trials, they are fine for either side of the screen) -if moving function is damaged (superior colliculus), subjects move their attention very slowly, such that the advantage of the cue is hard to see -if engaging function is damaged (thalamus), subjects don?t seem to use the cues at all, for invalid OR valid trials The beam metaphor proves false for these reasons: -moving attention greater distances doesn?t take a longer time -moving isn?t slowed down by intervening objects/stimuli -things outside the beam are actually inhibited -attention really focuses on an object, not a region of space Searching Sometimes you know what you want to attend to, but you?re not currently focused on it, so you need to switch your attention. Two types of searches: Conjunctive searches ? multiple things (conjunction of features) you have to evaluate before you find what you?re looking for (number of stimuli in array greatly affects reaction time); a serial search Disjunctive searches ? only one thing (distinguishing features) you are looking for, nothing else like it out there (number of stimuli barely affects reaction time); a parallel search Anne Treisman?s interpretation of these searches: Color maps and orientation maps enable the mind to find an object of one feature very easily, but an object with multiple features requires a synthesis or conjunction of the maps throughout the search Evaluating You must always be evaluating other stimuli to make sure you don?t miss anything important Stimuli ( processing of physical characteristics ( processing of semantics ( awareness ? early filter ? late filter Dichotic listening test (Cherry) -people don?t remember words from unshadowed ear -people don?t notice if speech is played backwards, or if the language changes -people do notice, however, when they hear a change in tone (man to woman voice) or if there was a gap Conclusion: early filter seems to exist more Even when people hear their name in the unattended ear, they only respond about 1/3 of the time Corteen & Wood, 1974: Phase 1: Fresno, New York, Dallas + electric shock Phase 2: Cities mentioned in unattended ear, people show some reaction This stands as evidence for a late filter Summary Early filter looks right. It is a good idea (perhaps evolutionarily advantageous) to sample and evaluate the environment?to at least some extent?in order to make sure you?re not missing anything crucial. Thus, the mind processes almost all incoming stimuli and evaluates it, switching if necessary.