Chapter 3 attention
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Chapter 3. Attention. OVERVIEW Selective attention (cognitive tunneling) Pay attention to multiple things in sequence – intentional but unwise choice Focused attention Pay attention to 1 thing – tendency to be distracted by external environmental info. Divided attention

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Chapter 3. Attention

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Chapter 3 attention

Chapter 3. Attention

  • OVERVIEW

    • Selective attention (cognitive tunneling)

      • Pay attention to multiple things in sequence – intentional but unwise choice

    • Focused attention

      • Pay attention to 1 thing – tendency to be distracted by external environmental info.

    • Divided attention

      • Pay attention to multiple things at the same time simultaneously- limited ability to time sharing performance

  • SELECTIVE ATTENTION

  • Visual Sampling

    • eye and visual sampling  seek information and searches for targets

    • Visual scanning behavior (attentional searchlight)

    • Eye fixation system

      • Fovea area perceives detail: about 2°of visual angle


Chapter 3 attention

  • Pursuit movement – the eye follows the target

  • Saccadic movement

    • discrete, jerky from one stationary in the visual field to next

    • Sometimes superimposed on pursuit movement

    • Saccade – suppresses visual input

    • Fixation – display info. processed during fixation

      • Location – center of the fixation

      • Useful field of view – diameter around the central location which info. is extracted

      • Dwell time – how long the eye remains at that location

  • Supervisory control context

    • scans the display of a complex system under supervision

    • allocates attention through visual fixations to various instruments

    • the target is known

  • Target search context

    • scans a region of the visual world

    • a target’s location and existence is unknown


Chapter 3 attention

  • Supervisory Control Sampling

    • Optimality of Selective Attention

      • stimulus environment -- channels and critical events

      • Mental model guides sampling

        • form a mental model of the statistical properties of events – frequency and correlations

      • Adjustment to event rate – sluggish beta

        • the sampling rate is not adjusted with event frequency

      • Sampling affected by arrangement – more likely to make horizontal scans than diagonal scans – simplifying rules and heuristics

      • Memory imperfect; sampling imperfect – sampling remainder

      • Preview helps – as the number of channels increases, fail to take advantage of preview

      • Processing strategies – cognitive tunneling

        • failed system, delayed feedback

  • Eye Movement in Target Search

    • Environmental Expectancies

      • fixate most on areas of containing the most information (Yarbus, 1967)

      • a scan path over same picture dependent upon seeking info. (Yarbus, 1967)

    • Display Factors and Salience

      • neither consistent pattern of display scanning nor optimal scan pattern in search


Chapter 3 attention

  • certain display factors to the allocation of visual attention

    • salience and abrupt stimulus onset in the visual periphery – may bias decision making

    • presence of unique stimuli (singletons) – slowed the detection of other targets

    • physical location in the display – the upper left, concentrated on the center (edge effect)

    • dominated by conceptually or knowledge-driven scan strategies

  • Display-Driven and Conceptually driven processing

    • they commonly interact – standardization of roadway and sign design

    • positive guidance – forecast the unexpected event

  • Search Coverage and the Useful Field of View

    • the highest acuity region of fovea – an angel of no more than 2 degrees

    • UFOV – a circular area around the fixation point -- 1 to 4 degrees of visual angle

      • size – determined by the density of information & the discriminability of the target

      • aging – restricted UFOV

      • training enlarge UFOV, benefits are equal across age groups

      • reduction in UFOV has serious implication such as driving

      • UFOV is sensitive to task demand in the foveal region

  • Fixation Dwells

    • survey dwells – short, used to establish the regions more likely to contain a target

    • examination dwells – used to provide a detailed examination of the region for an embedded target


  • Chapter 3 attention

    • difficulty of information extraction

      • low familiarity, low frequency, and out of context – higher information content (longer dwells)

      • expertise

  • Visual Search Models

    • How long to find a target? What is the probability in a given period of time?

    • Drury’s Model (1975, 1982)

      • 1st stage – target search stage

        • the probability of locating a target increases with more search time (fig. 3.2) – diminishing rate

      • 2nd Stage – decision stage

        • uses the expectancy of flaws to set a decision criterion

    • Variables affecting search speed (fig 3.3)

      • the number of elements to be searched – serial search (50 msec/item)

      • exceptions to serial search – one level along one salient dimension

        • greater search efficiency for parallel than serial

        • preattentive (requiring few attentional resources) for parallel and attentive for serial

      • serial search – the target is difficult to discriminate from distractors

      • exceptions to serial search – the presence of features rather than absent

        • different discriminabilities of targets in the two situations


  • Chapter 3 attention

    • dispersion of targets -- scanning distance and visual clutter trade off

    • any of several different target types slower than only one

      • exception – a single common feature

    • extensive training – automaticity  parallel search (consistent mapping not varied mapping)

  • Structured Search

    • Basics

    • information that may help guide the search is available

    • Application: Menus

    • target items are reached in the minimum average time (fig 3.4)

    • linear visual search model – frequently searched items positioned toward the top of the menu

    • optimal number of items per menu is between three and ten (Lee and MacGregor, 1985)

    • criterion-based model (Pierce, Sisson, and Parkinson, 1992)

      • the effect of similarity in menu search

  • Directing Attention

    • advise an operator in advance where attention should be directed

    • more accurate as the stimulus-onset asynchrony between the warning (cue) and the target increases – SOA=200ms more effective than SOA=50ms

    • peripheral cues (out of foveal area) – more effective with short SOAs, a transient effect, stimulus-driven, automatic process

    • central cues – more effective with longer SOAs, long lasting, goal-directed, controlled interpretation


  • Chapter 3 attention

    • PARALLEL PROCESSING AND DIVIDED ATTENTION

      • Preattentive Processing and Perceptual Organization

        • visual processing of a multiple-element world – two main phases

          • preattentive phase (STSS, automatic, grouping) and attentive phase (perception, selecting)

        • Gestalt psychologists (fig 3.5) – items to be preattentively grouped together on the display -- proximity, similarity, common fate, good continuation, closure  high redundancy

        • all items of an organized display must be processed together to reveal the organization (parallel processing) -- global or holistic processing

        • single object within the display -- local processing (fig 3.6) -- response conflict – global precedence

        • emergent features – global property of a set of stimuli (displays) (fig 3.8)

        • global processing tends to be preattentive and automatic -- reduce attentional demands

          • Gestalt principles – produce groupings oremergent features

          • spatial proximity of different elements compatible with task demands

      • Spatial Proximity

        • Overlapping Views: The Head-Up Display

        • although spatial proximity will allow parallel processing, it certainly will not guarantee it

          • Neisser and Becklin (1975) – separation defined not only in terms of differences in visual or retinal location but also in terms of the nature of the perceived activity

          • Wickens and Long (1995) – an unexpected obstacle was detected more poorly with the HUD than with the head-down configuration -- HUD could improve control of position during landing, both in view and when the runway was obscured by clouds


    Chapter 3 attention

    • the HUD appears to facilitate parallel processing of scene and symbology when the pilot expects the stimulus and interferes when the stimulus is quite unexpected

    • conformal nature of the symbology

    • Visual Confusion, Conflict, and Focused Attention

    • spatial proximity – confusion

      • spatial density little effect on visual search time

      • Wickens and Andre (1990) -- critical variable in predicting performance is the degree of spatial separation of relevant item from irrelevant, not the spatial separation between the relevant items themselves

      • Holahan, Culler, and Wilcox (1978) – to locate and respond to a stop sign in a cluttered display is directly inhibited by the proximity of other irrelevant signs in the UFOV

      • Eriksen and Eriksen (1974) -- perceptual competition – a failure of focused attention caused by the competition (ex. UHP)

        • response conflict (ex. FHF), redundant gain (ex. HHH)

    • Object-Based Proximity

    • different attributes of a single stimulus object at one spatial location

      • concurrent processing of elements lying close together in space (space-based model of attention)

      • concurrent processing occurs when elements lie within a single object (object-based model)

    • Stroop task – subject is asked to report the color of a series of stimuli as rapidly as possible

      • multiple dimensions belonging to s single object are likely to be processed in parallel

      • integral dimensions produce a cost for a filtering task and a benefit with redundant dimensions


    Chapter 3 attention

    • Applications of Object-Based Processing

      • in cognitive psychology, an object has three features

        • surrounding contours or connectedness between parts

        • rigidity of motion of the part

        • familiarity

      • benefits of objects in two contexts

        • conformal symbology – mapping of display objects to real-world objects

        • object displays – multiple information sources are encoded as the stimulus dimensions of a single object

      • Conformal Symbology and Augmented Reality

      • conformal symbology helped the pilot divide attention between the display and the world beyond, align the display object to the real object, and reduce tracking error

      • Object Displays

      • parallel processing of object features to create multidimensional object displays (fig 3.10)

    • The Proximity Compatibility Principle

      • three ways in which multiple display channels can be integrated: emergent features, spatial proximity, object integration

      • proximity-compatibility principle – whether different tasks are served differently by more or less integrated displays

      • to the extent that information sources must be integrated, there will be a benefit to presenting those sources either close together, in an object-like format, or by configuring them to create emergent features


    Chapter 3 attention

    • to the extent that information sources must be treated separately, the benefit of the high-proximity object display will be reduced, if not sometimes reversed

    • close proximity increases the possibility of parallel processing

    • close proximity and objectness can create useful emergent feature that help information integration if they correspond to the key variables of the task

    • emergent features can hurt performance if they are not mapped into the task

    • response conflict can result if proximity combines variables that require focused attention

    • Color Coding

    • benefits

      • rapid localization

      • capitalizes on population stereotypes

      • tie together spatially separated display elements

      • redundancy in combination with shape, size, or location

    • limitations

      • failure of absolute judgment – five or six colors, glare or low illumination (affected by ambient light)

      • no ordered continuum – brightness (saturation) rather than hue

      • population stereotype – poor design with a conflict meaning

      • irrelevant color coding can be distracting -- display-cognitive compatibility


    Chapter 3 attention

    • ATTENTION IN THE AUDITORY MODALITY

      • omnidirectional – no analog to visual scanning as an index of selective attention

      • transient

    • Auditory Divided Attention

      • an unattended channel of auditory input remains in preattentive STAS (3 – 6 sec)

      • attention switch

        • on – examined

        • off – LTM (preattentive) – pertinent enough focused attention

      • negative priming -- information presented in an unattended channel is temporarily inhibited for several seconds following presentation – slower

      • auditory object as a sound with several dimensions -- parallel processing

    • Focusing Auditory Attention

      • monaural and dichotic listening – large benefits of dichotic over monaural listening in filtering out the unwanted channel

      • cocktail party effect – auditory selective attention (pitch, intensity, semantic properties)

      • auditory attention can be directed by “cueing”

    • Cross-Modality Attention

      • parallel inputs across modalities

      • redundancy gain -- speeds up processing

      • dividing attention between modalities may be better than dividing attention within a modality

      • visual dominance over auditory and proprioceptive


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