PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Spatial Attention: Posner TaskSlide 12Find the T:Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Find the Blue T:Find the Blue TSlide 23Slide 24Slide 25Treisman’s Attention ModelSlide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Stroop TaskSlide 35Slide 36StroopSlide 38Sharing Attention: Dual TasksSlide 40Slide 41Slide 4207.1307.1507.1607.1707.2107.22Slide 49Slide 50Slide 51Slide 52Slide 53Slide 54Slide 5507.28p.281Slide 58Slide 59Slide 60Slide 61Slide 62Slide 63Slide 64Slide 65Slide 66Slide 67Slide 68Slide 69Slide 70Slide 71Slide 72Slide 73Slide 74Slide 75Slide 76Slide 77Slide 78Slide 79Slide 80Slide 81Slide 82Slide 83Slide 84Slide 85Slide 86Slide 87Attention - OverviewDefinitionTheories of AttentionNeural Correlates of Attention•Human neurophysiology and neuroimaging•Single cell physiology – cellular mechanismsDeficits of Attention•Unilateral neglectAttentionEveryone knows what attention is. It is the taking possession of the mind in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought. Focalization, concentration of consciousness are of its essence. It implies withdrawal from some things in order to deal effectively with others…- William James (1890)Circa 1880Attention: Two ComponentsTonic attention (vigilance): setting arousal level, detection efficiency, signal-to-noise ratio. – brainstem reticular formation, basal forebrain, locus coeruleus, etc.Selective attention: space-, object-, modality-selective attention. – temporal and parietal cortex.What Does Attention Do?1. Maintaining alertness and vigilance2. Orienting to sensory events-overt vs. covert3. Selection of sensory events- early vs. late selection4. Detecting targets- limits on capacity- processing bottlenecks5. Controlling access to memory and awarenessWhere Does Attention Take Place?Different sensory modalities (vision, audition etc.).Attention is a distributed function.Different processes – different anatomical substrates.Attention as Competition for “Neural Resources”Kastner and Ungerleider, 2000Attention: A Covert Spotlight?Helmholtz’ experiment: Attention selects informationThe Cocktail Party EffectShadowing - selective listeningCherry’s dichotic listening experimentsThe Filter Theory of AttentionBroadbent (1958)However, even unattended information can “break through” and produce a shift in attention or orienting. Treisman’s attenuation theory.Where Does the Selection Occur (Early or Late)?Early selection: before full analysis of inputLate selection: at or after semantic encodingSpatial Attention: Posner TaskAAttention switches to here(but eyes don’tmove)Target mightappear here:A or here:TimeFixation PointCue75%accurateAttention and OrientingPosner et al., 1980Voluntary orienting (expectancy) results in faster reaction times. Attention affects perceptual information processing, attention is spatial  “mental spotlight”Find the T:Find the T:TLLLLLLLFind the T:Find the T:TLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLFind the T:Find the T:TLLLLLLFind the T:Find the T:TLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLFind the Blue T:Find the Blue TLTLLTTTTTLFind the Blue T:Find the Blue TTLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLTTTTTTTTTTTTTTTTTTTTLTSearching a Scene“pop-out”conjunction-search(sequential spotlight)Treisman’s Attention ModelQuickTime™ and aPhoto - JPEG decompressorare needed to see this picture.QuickTime™ and aPhoto - JPEG decompressorare needed to see this picture.QuickTime™ and aPhoto - JPEG decompressorare needed to see this picture.QuickTime™ and aPhoto - JPEG decompressorare needed to see this picture.QuickTime™ and aPhoto - JPEG decompressorare needed to see this picture.Competition and Visual SearchInterpretation of Treisman’s results:Feature search requires look-up within one feature map (bottom-up saliency-based mechanisms).Conjunction-search requires coordination of multiple feature maps in register, serial search under guidance of visual attention (top-down influences of spatial or object-based attention). “Multiple objects are competing for neural representation.”Inhibition of ReturnLocalized exogenous cues (light flash) can lead to faster performance at that location (within 250 msec) – then there is an inhibitory aftereffect (inhibition of return).The Saliency MapIdea originally proposed by Koch and Ullman, 1985.Saliency map = encoding “visual conspicuity”, or saliency.Two mechanisms: -fast, parallel pre-attentive extraction of visual features.-slow, sequential focal attention, winner-take-all, inhibition-of-return.The Saliency MapThe Saliency MapThe Saliency Map: ApplicationStreet signsThe Saliency Map: Application“Replication” of Treisman’s experiments:Stroop TaskBlueGreenYellowRedYellowYellowGreenBlueRedGreenBlueRedGreenYellowBlueGreenStroop Task********************************************************************************Stroop TaskBlueGreenYellowRedYellowYellowGreenBlueRedGreenBlueRedGreenYellowBlueGreenStroop•Failure of selective attention•Race model–Word name is processed automatically–Color is not so automatic–Both arrive at the same time, we have a hard time attending to the relevant stimulus attribute–Doesn’t happen upside downStroop Task.Sharing Attention: Dual Tasks•Do two things at once: can they be performed at the same time?•Do they interfere?•Experiment has 3 conditions•Task A alone•Task B alone•Task A and B together at the same timeSharing Attention: Dual Tasks•Example:•Pat head and rub belly•Now speed up just your belly•If you can’t do it, it suggest that they share the same processing capacity •Same brain area?Sharing Attention: Dual Tasks% of LinesExample:Task A: Can read 30 pages an hour when not waching tvTask B: Can recite 85% of Gilligan’s lines before he does when not reading at the same time.Can you wach Gilligan and still read as quickly?(Assume you adjust your reading speed to maintain the samecomprehension level)Pages perhour0 50% 100%0102030abc40Attention – NeurophysiologyHillyard’s experiments – dichotic listening: attention-dependent effect on ERP amplitude.Early or late?Study by Woldorff et al., localization of an early (20-50 ms latency) attention effect using ERP(F)/MRI).Adapted with permission from Hillyard, S.A., Hink, R.F., Schwent, V.L., and Picton, T.W., Electrical signs of selective attention in the