Prof. Greg Francis1PSY 310: Sensory and Perceptual ProcessesPurdue UniversityStimulus-responsePSY 310Greg FrancisLecture 27Every second counts.$20.97 is thisOK?YESNOPurdue UniversityPerception and action Are intricately related to each other Can be used to study other aspects of human behavior Consider responding to a simple stimulus Some responses are more “natural” than otherresponses Suggests structure to the representation of information andcognitive processesProf. Greg Francis2PSY 310: Sensory and Perceptual ProcessesPurdue UniversitySimon effect Consider a task where you need to discriminate betweenred and green squares Act with the right hand if red Act with the left hand if greenPurdue UniversitySimon effect Position of the red square could be left or right Should respond with the right hand regardless of positionCongruent with actionIncongruent with actionProf. Greg Francis3PSY 310: Sensory and Perceptual ProcessesPurdue UniversitySimon effect Position of the green square could be left or right Should respond with the left hand regardless of positionIncongruent with actionCongruent with actionPurdue UniversitySimon effect Subjects are to ignore the position of the stimulus anduse only the color to determine which action to make They cannot Reaction time is faster for congruent trials than forincongruent trials CogLab data (79 subjects) Congruent Trials -> 500 ms Incongruent Trials -> 527 ms Simon effect = 27 msProf. Greg Francis4PSY 310: Sensory and Perceptual ProcessesPurdue UniversitySimon effect Not restricted to colors In general, people respond faster (and more accurately)when the action to be made is in the same relative positionas the stimulus Sounds Touches Words The Simon effect is usually fairly small (5-50 ms) but itoccurs in many different places How important can it be?Purdue UniversityCredit Card Reader Anyone shop at the PaylessGrocery store? To use their credit cardmachine at the checkoutyou face something like this You slide you card, andthen are asked forverification of paymentProf. Greg Francis5PSY 310: Sensory and Perceptual ProcessesPurdue UniversityCredit Card Reader The display looks like this The button for “YES” is on theright The button for “NO” is on theleft The YES word is on the left The NO word is on the right Incongruent pairing Adds time to the checkoutprocess$20.97 is this OK?YES NOPurdue UniversitySignificance Kroger operates about 3700 stores Under various names: Payless, Ralphs, Dillons, Smith’s, Baker’s, JayCFood Stores, City Market, Fry’s, Hillander, Owens, QFC, Gerbes Kroger stores average 6500 customers at each store each week Confusion generated by the “Simon Effect” might produce 3seconds extra time spent processing a checkout Then customers are wasting time in a check out lane 6500 x 3 seconds = 19,500 seconds = 325 minutes For all stores 3700 x 325 minutes = 20,041 hours Every week! Grocery stores operate on very thin profit margins, and people hatestanding in line A simple fix would help!Prof. Greg Francis6PSY 310: Sensory and Perceptual ProcessesPurdue UniversityApplied psychology Studies of perception and action can be used to build improveddevices The design of roads, road signs Nuclear power plants Space shuttle control systems Automobiles Computer interfaces Staplers Caps of bicycle inner tubes Look at two examples from my laboratory Keyboards MapsPurdue UniversityComputer interface Although there are a variety of newtechniques for interacting withcomputers, the keyboard remains one ofthe most flexible devices for entering textinformation The standard in North America is theQWERTY keyboard Works best with 10-finger typingProf. Greg Francis7PSY 310: Sensory and Perceptual ProcessesPurdue UniversityMilitary helicopters The QWERTY keyboardis neither possible norappropriate for somesituations AH-64D attackhelicopterPurdue UniversityKeyboard for AH-64D Pros Compact space: Goodfor one-finger typing Alphabeticalarrangement: Might aidsearch for letters Cons Learning needed Relatively slow text entryProf. Greg Francis8PSY 310: Sensory and Perceptual ProcessesPurdue UniversityText entry Consider entering theshort text message“RGR” (ROGER)Purdue UniversityText entry Consider entering theshort text message“RGR” (ROGER) Hit the “R” key on rightsideProf. Greg Francis9PSY 310: Sensory and Perceptual ProcessesPurdue UniversityText entry Consider entering theshort text message“RGR” (ROGER) Move to the left side tohit the “G” keyPurdue UniversityText entry Consider entering theshort text message“RGR” (ROGER) Move back to hit the “R”key againProf. Greg Francis10PSY 310: Sensory and Perceptual ProcessesPurdue UniversityText entry Consider entering theshort text message“ENRT” (EN ROUTE) First hit the “E” keyPurdue UniversityText entry Consider entering theshort text message“ENRT” (EN ROUTE) Move down and over to hitthe “N” keyProf. Greg Francis11PSY 310: Sensory and Perceptual ProcessesPurdue UniversityText entry Consider entering theshort text message“ENRT” (EN ROUTE) Move right to hit the “R”keyPurdue UniversityText entry Consider entering theshort text message“ENRT” (EN ROUTE) Move left to hit the “T” keyProf. Greg Francis12PSY 310: Sensory and Perceptual ProcessesPurdue UniversityOptimized keyboard We explored how to placethe alphabet characters onthe keypad in such a way asto minimize movement timewhen entering text We interviewed Apachepilots to identify the type oftext messages that areentered into the keyboard Relatively small text corpusidentifiedEN ROUTEENRTBAQCOMMUNICATIONS CHECKCOMO CHKROGERRGRLOUD AND CLEARLCGO TOGO2Purdue UniversityPerception and action The time needed to move a finger (or stylus) toward a target of agiven size (Sj) at a certain distance (Hij) is well-modeled by Fitts’Law (1954) The term Im is a free parameter. For well-practiced subjects underideal situations, it is around 100 milliseconds We will be interested in relative changes in movement time ratherthan absolute magnitudes The time needed to enter a word is modeled as the sum of timeneeded to move from one key to the nextProf. Greg Francis13PSY 310: Sensory and Perceptual ProcessesPurdue