Page 1Attention and Human FactorsFebruary 20, 2001Early or Late, which is right?In some studies, early filter seems right (as when people can’t report anything from the unattended ear)In other studies, they sometimes get their name, they show some effect in the GSR study.Early filter looks rightIn studies where people seem to get semantic information, they may be actually rapidly switching attention to the ear they are supposed to be ignoring. When you guard against this, it looks like they don’t get much information from the unattended ear.What is selected?When we say that attention is selecting, what is it selecting? (this question has usually been considered in vision, not audition)Two possibilities have been offered: 1. It selects objects2. It selects locations in space (moves like a beam.Kwak et al (1991)Examined the time it took people to shift attention different distances. There was not an effect of distance; this result is not consistent with the beam idea.Sperling & Weichselgartner (1995)Idea was to test whether an intervening object disrupts movement of attentionDigitsLettersDigits appear very rapidly (10/second) and so do letters. Keep eyes on digits, but attention on letters; then, when letter “C” appeared, switch attention to digits and report the first you see.Page 2DigitsLettersDigitsLetterscharactersNo stimuli intervening Stimuli interveningHow quickly people could move attention was the samein the two conditions, indicating that the intervening characters did not slow the movement of attention.How does selection operate?This question has usually been tested in visual search paradigms.In the next stimulus array, search for the redtargetStill pretty easy even with more varied distractors (still search for red)Page 3This sort of search works with attributes other than color, too.In the next array, look for the circle.Again, look for the circleBut watch what happens when you search an array in which the target is NOT defined by a single feature.Look for the red circle But there will be non-red circles and red non-circles.Page 4Typical resultsNumber of stimuli in array030Disjunctive searchConjunctive searchReaction timeInterpretationNumber of stimuli in array030Disjunctive search--ParallelConjunctive search--SerialReaction timeTreisman’s interpretationColor mapsOrientation mapsredbluegreenMap of locationsattentionHuman Factors EngineeringHuman Factors EngineeringApplication of knowledge of human performance and limitations to the design of effective systemsGoal to reduce human error, increase productivityHuman ErrorHuman error is the primary cause of 60 to 90% of major accidents in complex systems such as nuclear power or aviationPage 5Human ErrorMany of these errors are the result of bad system design or bad organizational structureHow to categorize human error?Classification of Human Error• Slips• Actions categorized by automatic routines• Lapses• Memory errors, forgetting• Mode Errors• Right action in the wrong contextSlipsThe right intention is incorrectly carried out• Intended action involves slight departure from routine• Action sequence is automated and not closely monitored by attentionSlipsExamples:• Pouring orange juice on waffles instead of syrup while reading the newspaper• Activate similarly configured and placed control (e.g. flaps and landing gear on a small airplane)Slips“ I intended to go home a different route in order to stop at a shop. My different route meant taking another turn off my usual circle. I was on my bike. I entered the circle, went past the turn I wanted and took the normal route home. It took about 15 seconds down the wrong road (normally the right one) before it clicked.Slips“ I intended to change from jeans into a dress. I undressed completely as if I were going to bed.”“Throughout January, I kept writing checks with last year’s date on them.”Page 6Slips“On leaving the room to go to the kitchen I turned the light off, although there were several people there.”LapsesFailure to carry out any action at all• Omission of step in automatic procedure• Often as a result of interruption• Crash of Northwest Airlines flight– Pilots were interrupted by air traffic control during a routine taxi checklist; when they resumed, they skipped an important checkLapses“In the shower this morning, I ‘came to’ to find that I didn’t know whether or not I had washed my hair. It was wet and there was no way of telling. I could have washed it and all the suds could have disappeared down the drain. I certainly had no recollection of anything except what I had just been thinking about.”Lapses“The anesthesiologist prepared a new IV solution and then proceeded to fill out some paperwork, in the process forgetting to switch IV’s at the appropriate time. The patient went into seizures and was without oxygen for over 5 minutes.”Lapses“I filled up at the gas station and then drove off, leaving the gas cap on the roof of the car.”“I didn’t know if I had put water into the kettle. I had to lift the lid to check.”Lapses– Ever wonder if you turned off the lights/stove?– Did you shut and lock the door?– Did you address and stamp the envelope?Page 7Mode ErrorsLike slips, but also have memory failure of lapses• Right action performed in wrong context because of lapse of memory of context• Example: Pilot shut down port engine instead of starboard one that was developing trouble. Crash followed power failure.Mode Errors“On Saturday mornings, I ride to the city through two large parks. On this particular Saturday, I was amazed to see people staring at me as I crossed the playing field on a footpath. Then I realized—my bike tire had a puncture and today I was in my car. Having forgotten that I was not on my bike, I had followed my customary cycling route.”Mode Errors“I threw my glasses in the wastebasket and kept some dirty tissues I was holding in my other hand.”“Walking up the front path to my friend’s house, I pulled out my own front door key and I was just about to place it in the lock when I realized my mistake.”Mode Errors“When I leave for work in the morning, I am in the habit of throwing two dog biscuits to my dog and then putting on my earrings. One morning, I threw the earrings to my dog and found myself trying to attach a dog biscuit to my ear.”Human Error Case StudiesSet Phasers on StunRental CarGenie in the BottleIn Search of the Lost CordAn Act of