Prof. Greg Francis 8/12/11 PSY 200: Intro. to Cognitive Psychology 1 Purdue University Attention PSY 200 Greg Francis Lecture 12 How could you not see it? Purdue University Attention  The world contains more information than we can fully interpret or process all at once  The ability to deal with some stimuli and not others is attention  not clear if there is an attentive system  or if attention derives from other systems Purdue University Information processing  Modern theories see cognition as information processing  much like a computer  Different systems have different capabilities, capacities, and speeds  Necessarily, some information is ignored because it is not processed Purdue University Attention  Part of attention seems to be due to mental effort on your part  attending a lecture  ignoring whispering around you  Part of attention seems a natural side effect of mental effort  ignoring the “uhs” and “ums” from a speaker  ignoring the feel of clothes on your body  Part of attention seems effortless  a loud noise Purdue University Magic trick  Pick any card  Memorize it  really study the card carefully to be certain you have it memorized Purdue University Magic trick  Now the computer will shuffle the cards and present them againProf. Greg Francis 8/12/11 PSY 200: Intro. to Cognitive Psychology 2 Purdue University Magic trick  Hey, the card you selected is missing  How did I know which card you would select?  Try it on the web at http://members.tripod.com/~andybauch/magic.html Purdue University Attention as processing  Mental effort either is or requires attention  Consider the following video (Simons & Chabris, 1999)  you will see two groups of people wearing either black or white shirts  each group is tossing around a ball  count how many passes are made by the white group Purdue University Attention as processing  Did you notice an unusual event in the video?  Let’s look at it again  Attention is a powerful force  when you are busy doing something else, you can fail to observe even very significant things  that’s why it is not a good idea to talk on a cell phone while driving a car Purdue University Drawing attention  Attention is focused by meaningful stimuli  Also focused by certain stimulus characteristics, especially changes  Flashes of light  Movement  Color  Think of advertising signs  Example Purdue University Drawing attention  Suppose these cues were masked by other changing stimuli  You might not notice the change at all  Demonstration Purdue University Attention  Another way to interpret these results is that attention is necessary to detect stimulus changes  Explains how people can “look” but not “see”  walking into doors  driving into trains  detecting changes on a radar screen  why magicians use flashes of light!Prof. Greg Francis 8/12/11 PSY 200: Intro. to Cognitive Psychology 3 Purdue University Attention effects  An illusion because people do not see stimuli or something else?  E.g., do not remember, do not recognize  In general, attention seems to strengthen stimulus representations if they are weak  Perceptual processing is better with attentional focus  Detection  Masking  Discrimination  Some neurons respond stronger to stimuli that are attended Reynolds et al., 2000"Purdue University Attentional paradox  If attention strengthens perceptual representations, we should lose perceptual veridicality  We might expect what is schematized below  But we normally do not experience this  Attention generally seems to strengthen information about a stimulus that is not perceptual  Maybe edges rather than surfaces? Attend red Attend green Stimulus Purdue University Attentional paradox  Sometimes attention can change perceptual properties  But then we have an incorrect perception of the properties of the visual scene  So it is difficult to understand how attention is helping here Tse, 2005"Purdue University More demos  If time permits, here’s some more demos  http://viscog.beckman.uiuc.edu/djs_lab/demos.html  Field  Living room  Phone call  Lunch conversation (9 changes)  Paris scene Purdue University Conclusions  Attention can have very powerful effects  help processing of focused on things  can cause unawareness of unattended things  Not precisely defined  characteristic of processing?  An “extra” system? Purdue University Next time  Methods of studying attention  What things influence attention  Timing, features  CogLabs on Attentional blink and Visual search due!  Should you pay $59.95 for Mega-speed