Prof. Greg Francis 1/2/13 PSY 200: Intro. to Cognitive Psychology 1 Purdue University Attention PSY 200 Greg Francis Lecture 13 Should you pay $59.95 for Mega-speed reading? Purdue University Attention  We saw last time that attention can have very powerful effects  when it is focused on one thing, you ignore other things  Today we want to consider some more specific properties of attention  and look at experimental methods that are used to study attention Purdue University Characteristics of attention  By identifying the properties and characteristics of attention we can deduce properties of the underlying systems that are involved in cognition  whether attention is thought of as a “system”  or as a by-product of other systems  Look at  temporal  featural Purdue University Attentional blink  Suppose you have to identify rapidly presented (100 ms) letters  e.g., detect J and/or K in a stream of letters M P K R W S Purdue University Attentional blink  Turns out that detection of first letter tends to make detection of the second letter very difficult  if it immediately follows the first  Attentional blink M P K R J S Purdue University Attentional blink  Measure frequency of detection  class data (183 observers) Implies that detecting the first letter causes you to miss the second letter!Prof. Greg Francis 1/2/13 PSY 200: Intro. to Cognitive Psychology 2 Purdue University Attentional blink  Suggests that processing the first target letter, “J”  uses up resources that would otherwise be used to process second target letter, “K”  attentional focus and refocus takes time and for this task takes approximately 400 ms S L N B J R K H ... J Once processing is done (a few hundred milliseconds), there is no difficulty detecting second letter. Purdue University Speed reading  Ever seen the ads for speed reading?  One is for a program called Mega Speed Reading  claims to teach you to read 25,000 words per minute  ==> 2.4 milliseconds for each word  impossible, if only by attentional blink!  The seller is skimming at best, and lying at worst Purdue University Visual search  Proofreading  Much of our time is spent looking for various things  Staplers, Road signs Purdue University Visual search  Time and type of processing can also be measured by having observers respond as quickly as possible when they detect a target  hypothesize that tasks that involve attention will be slower than “perceptually” based tasks  expect attention to depend on the number of things that must be searched  Typically, we distinguish between a target and distracters by one or more features  we vary the number of distracters  and measure reaction time Purdue University Set Size  In some situations, more distracters make search take longer  fast Purdue University Set Size  In some situations, more distracters make search take longer  slowProf. Greg Francis 1/2/13 PSY 200: Intro. to Cognitive Psychology 3 Purdue University Feature Search  But if the target differs from the distracters in the right way, search can be fast even with lots of distracters  “pop out”  This often happens when the target has a unique feature relative to the distracters  shape Purdue University Feature Search  But if the target differs from the distracters in the right way, search can be fast even with lots of distracters  “pop out”  This often happens when the target has a unique feature relative to the distracters  color Purdue University Conjunctive Search  But if the target has shared features with different distracters, search is difficult  No “pop out”  This often happens when the target is defined by a conjunction of features relative to the distracters  Orange rectangle: color and shape Purdue University Visual search experiment  Four types of responses  1) Feature - present (can respond as soon as see target)  2) Feature - absent (must examine all stimuli before sure target is not present)  3) Conjunctive - present (can respond as soon as see target)  4) Conjunctive - absent (must examine all stimuli before sure target is not present) Purdue University CogLab feature search  Few distracters -easy Purdue University CogLab feature search  Many distracters - still easyProf. Greg Francis 1/2/13 PSY 200: Intro. to Cognitive Psychology 4 Purdue University Conjunctive search  Few distracters - fairly easy Purdue University Conjunctive search  Many distracters - difficult Purdue University Visual search  CogLab data (182 observers) Purdue University Interpretation  Feature maps: color, shape  Feature search can identify target within either feature map Shape Color blue green corners arcs No searching required!"Purdue University Interpretation  Feature maps: color, shape  Feature search can identify target within either feature map Shape Color blue green corners arcs No searching required!"Purdue University Interpretation  Feature maps: color, shape  Conjunctive search cannot identify target within either feature map alone Shape Color blue green corners arcs Requires search by comparison across feature maps. Serial process that takes timeProf. Greg Francis 1/2/13 PSY 200: Intro. to Cognitive Psychology 5 Purdue University Interpretation  Feature maps: color, shape  Conjunctive search cannot identify target within either feature map Shape Color blue green corners arcs Requires search by comparison across feature maps. Serial process that takes time Purdue University Visual search  Conjunctive search for target absent has a slope twice as steep as for target present  Because when the target is present you find it, on average, after searching half the items and then can stop the search  For target absent searches, you must search all items to verify each is not the target Purdue University Automaticity  When a task is unfamiliar it seems to require a lot of attention to perform  Later it requires less attention  riding a bike  driving a car  typing  tying shoelaces » http://www.fieggen.com/shoelace/knots.htm Purdue University Automaticity  The