Attention Effort and Resource Allocation September 18 2008

Attention, Effort, and Resource Allocation September 18, 2008

What Is Attention? • “Every one knows what attention is. It is the taking possession by the mind, in a 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 with others…” (James, 1890, p. 403) • http: //viscog. beckman. uiuc. edu/djs_lab/demos. html

Attention is. . . • An attitude of mind • Relative proportion of activated traces to all memory traces – active workspace • Some form of energy or desire involving will or effort • A filter • An allocation of resources • A spotlight, a selective attenuator

Characteristics • General agreement regarding two characteristics outlined by James: – Bottom up (sensory) attention driven by environmental events (stimulus-driven; exogenous) – Top down (volitional) attention to both external and internal stimuli (goal-driven; endogenous) • May be thought of as automatic vs. controlled, respectively.

Automatic Vs. Controlled Processing Distinction • Automatic processes – no capacity limitation; fast – do not require attention, effort – difficult to modify once learned • Controlled processes – limited in capacity; slow – require attentional resources, effort – can be used flexibly in changing circumstances

Ventral right frontoparietal network and target detection (detection of low-frequency targets; these regions not active in the antipation period) Stimulus-driven or bottom-up attention Corbetta & Shulman, Nat Rev NSci, 2002

Dorsal frontoparietal network for top-down control of visual attention (these regions active in the anticipation period) Corbetta & Shulman, Nat Rev NSci, 2002

Functional Components of Attention What gains access to WM? Regulation of channel signal strength Automatic filtering for behavioral importance Knudsen, Ann Rev NSci, 2007

Purposes of Attention • • Cope with inherent capacity limitation of brain Facilitate stimulus detection Facilitate stimulus perception Facilitate thinking James Facilitate memory Recruit relevant processors Prepare for action

Varieties of Attention • Focused attention (processing only one input at a time) – Orienting to sensory events – Detecting signals for focal (conscious) processing • Divided attention (processing multiple inputs according to nature of inputs and goals) • Maintaining a vigilant state

Varieties of Attention

Dimensions of Attention • Focality (detection vs. selective attention) • Duration (brief vs. sustained attention) • Input channel – Visual attention • Spatial • Object-based – Auditory attention • What, where • Cognitive effect (facilitation vs. inhibition)

Why have an attentional system? Processing economy -brain as a limited-capacity processor; that which is selected should be consistent with goals and expectations

Early Visual Attention • Interface between Attention and STM: Attentional blink http: //www. rit. edu/~gssp 400/Blink/blinkinstr. html

Early Visual Attention (Cont’d) • Interface between Attention and STM: Repetition blindness

Early Visual Attention • AB and RB can be doubly dissociated (Chun) – Making targets different from distractors alleviates AB but not RB – Enhancing episodic distinctiveness of the two targets eliminates RB but not AB • May represent different things – AB represents bottleneck in attentional processing – RB reflects failure of token individuation http: //psych. hanover. edu/Java. Test/Cognition/attentionalblink_instructions. html

Selective Attention • Selective processing of some information but not others • Filter vs. capacity models • Important research paradigms – Dichotic listening http: //www. humnet. ucla. edu/humnet/linguistics/p eople/schuh/lx 001/Dichotic/dichotic. html – Shadowing

Dear Linguist: I am hoping you might be able to provide some information for me regarding dichotic listening. I work in a call center in Vancouver, Canada. The position I work in requires that we monitor 2 separate phone lines at the same time with 2 headsets (one on each ear) for 8 hour shifts. We monitor the content of messages being left by callers, and subsequently accept or refuse their recorded greeting/message. There is a fairly large staff (approx. 60 employees) here that monitors the phone lines 24 hours a day, 7 days a week. The content of the messages is often rude and unsavory - we monitor a singles meeting place chat connector and callers can get fairly explicit - but this is not the issue that concerns me. The position did involve listening to single lines before a company expansion over a year ago when it changed to double-line monitoring. It seems that this double listening is affecting people negatively. Having done this for 8 months now, I know that I have been experiencing psychological trauma (depression, confusion, irritability, chronic headaches etc. ), as have a number of my co-workers. My question is this: Is this type of dual listening harmful in any way, or furthermore, have any studies been done in regards to the effects this type of extended exposure to dual listening may have on the human brain or psyche? I have just started looking into this - your name came up in a web search for dichotic listening - and I would greatly appreciate any information or reference that you could pass on. Thanks. -Name, Occupation

Cherry (1953) • Interested in attentional “popout” of relevant information (“cocktail party effect”) • Two messages, same voice, both ears: subjects could invariably separate messages, but with difficulty; uses physical/source characteristics • Dichotic listening with shadowing – Recalls little if any content from other ear – Often doesn’t recall language – Can recognize it as speech/nonspeech, and can recognize male-female

Broadbent (1958) • Influential paper on focused (selective) attention; felt by many to be a critical ‘cornerstone’ paper in cognitive psychology • Influenced by Cherry’s shadowing results • Used dichotic listening, and found a strong tendency to report digits ‘by ear’, thus reflecting a tendency to select based on perceptual/physical characteristics of the input

Broadbent’s Filter Theory Stimulus #1 Stimulus #2 Limited capacity STM Sensory register/buffer Selection Filter

Problems with Broadbent’s Theory: Recall across ears can be organized (automatically? )

Problems With Broadbent’s Filter Model • Sometimes attention doesn’t follow input source: Gray & Wedderburn (1960) fan rage tic out tas ous • Can demonstrate that “unattended” information is processed phonologically or semantically: Corteen & Wood (1972) – EDR’s to shock-associated words in an unattended channel – city name study

Early Vs. Late Selection • “Early” theories (Broadbent, Treisman) – selection takes place well before extensive (e. g. , semantic) analysis takes place – contradicted by studies showing semantic effects in unattended ear • “Late” theories (Deutsch & Deutsch) – extensive analysis of stimuli takes place before selection – raises issue of benefits of selective attention – shadowing delayed by presentation of a synonym in the other ear; recall biased by semantic interpretation (e. g. , bank-river, vs. bankmoney)

Broadbent Sensory register Selection Filter STM Stim#1 Stim#2 Treisman Sensory register Attenuator STM Stim#1 Stim#2 Deutsch & Deutsch Sensory register Stim#1 Stim#2 STM

A Hybrid: Perceptual Load Theory • Everyone has limited attentional capacity • The amount of attentional capacity allocated to the main task depends on its perceptual load, which is determined by “the number of units in the display and the nature of processing required for each unit” (Lavie & Tsal, 1994, p. 185) • “Any spare capacity beyond that taken by the highpriority relevant stimuli is automatically allocated to the irrelevant stimuli” (Lavie, 1995, p. 452). Thus, the total available attentional capacity is always allocated to processing • Early selection occurs when load is high; late selection dominates when load is low

Evidence for Perceptual Load Theory r t x p q k _ _ x _ _ _ • Mean target identification time as a function of distractor type (neutral [N] vs. incompatible [Z]) and perceptual load (low vs. high). Based on data in Lavie (1995). Nature of distractor has more effect on time when perceptual load is low.

A Capacity Model Kahneman (1973) • Supplements previous bottom-up analysis with a consideration of topdown influences • Emphasizes concept of processing resources • Attention and mental effort are strongly correlated • Arousal can work to increase processing resources

Kahneman’s Model

Understanding the Effects of Attention is Important When there are Limitations on Processing • Resource-limited processes – Processes dependent on the availability of resources that can be devoted to task solution – Applying more effort or processing resources increases task performance • If output not available until task is finished, then devoting more resources decreases RT • If output continuously available, then performance level increases • Data-limited processes – Processes dependent upon the quality of data input, rather than upon resource allocation • Applying more resources may have little effect on performance • Most processes have both resource- and data-limited components

Present Absent “Yes” True Positive False Positive “No” False Negative True Negative Basic Signal Detection Framework

Focused Visual Attention • The Attentional “Spotlight” model – items within a small portion of the field can be seen clearly – Posner’s ‘covert’ shifting of the spotlight – Problem: proximity not always facilitative –e. g. Driver & Baylis, 1989 – common movement • Zoom-lens model (Eriksen & Yeh, 1985) – – Magnification inversely proportional to FOV ‘magnification’ can be increased or decreased Grouping processes affect spatial extent of attention Problem: attention can be object-based; objects outside the zoom can be processed or even inhibited

Evidence for Spotlight • Location-specific facilitation of attention – RT’s faster when object appears in cued location – search for target letter and report orientation of “U”; done better when two letters are close together T vs. T

Focused Visual Attention • The Attentional “Spotlight” model – items within a small portion of the field can be seen clearly – Posner’s ‘covert’ shifting of the spotlight – Problem: proximity not always facilitative –e. g. Driver & Baylis, 1989 – common movement overrides proximity • Zoom-lens model (Eriksen & Yeh, 1985) – – – Magnification inversely proportional to FOV ‘magnification’ can be increased or decreased Grouping processes affect spatial extent of attention Split attention (Awh & Pashler) Problem: attention can be object-based

Experiments Demonstrating Split Attention (a problem for the zoom-lens model) • Awh and Pashler (2000). • (a) Shaded areas indicate the cued locations and the near and far locations are not cued; (b) probability of target detection at valid (left or right) and invalid (near or far) locations. • Based on information in Awh and Pashler (2000).

Object-Based Attention Behrmann, et al (1998) JEP: HPP, 24, 1011 -1036

Inhibition in Attention

Inhibition in Attention (Cont’d) Negative Priming Paradigm Prime Probe Task = name red drawing Attended repeat Unrelated Unattended repeat

Attention as Facilitation A Preattentive Processing Further Cognitive Processing Stimulus 1 Stimulus 2 ATTENTION Attention as Inhibition B Preattentive Processing Further Cognitive Processing Stimulus 1 Stimulus 2 ATTENTION

Inhibition of Return (IOR) • “A reduced perceptual priority for information in a region that recently enjoyed a higher priority” (Samuel & Kat, 2003, p. 897) • A bias favouring novel locations and objects • Posner and Cohen (1984) – IOR due to inhibition of perceptual and/or attentional processes • Taylor and Klein (1998) – IOR due to inhibition of motor processes • Prime and Ward (2004) ERP study – IOR is a perceptual phenomenon not in motor response

Models of Visual Search • Feature integration model – rapid initial parallel process not dependent on attention – subsequent attention-dependent serial processes in which features are combined to form objects – attention provides “glue” binding features together into an object; can only do this one object at a time – feature combination affected by stored knowledge – without focused attention, features combined randomly, producing ‘illusory conjunctions’

Display Size Effect L L L L L L L L L L L L L L L L L L L L L T L L L L L L L L L Find the “T” L L T L

Feature Search & Feature Singletons L L L L L L L L L L L L O L L L L L L L L L L L Find the “O” L L L L L L L O O O O O O O O O O O O O O O O O T O O O O O Find the “T” O O O O O O O

Treisman & Gelade (1980) L L L T L L T L L L T L L L T L T L L L L T L L T T L L L L L T T T L L L L T L T L L L T T L L L T T L L Find the “Green T” S L R M T N X A Y W S B X N I F M I Q W A S Z X L K P M B E W E R U I N S L R M T N X A Y U O W L X P D G H Find the “B lue Letter”

Feature Conjunctions & Illusory Conjunctions S S S S Find the “$” (or “is there a $? ” Find the triangle (or “is there a triangle? ”

Similarity vs. Feature Conjunctions Q @ A ? B * % E P ^ $ * @ W ! M * > Q K & O S G B W S E & J P / A C # ! W + N % S + F + Q ( Z X N * Q ( T K T ) H A S O S B K I Y & S S Y W F ^ T Y T Z J C Z Q { [ B I @ U K P % D K R C H S # X O G K C U A M L D X S S K U D = V * ) B N S > } r @ a ? c * x f q ^ @ # @ s y b ! # p l ! s t h c p Find the “R” t n r < ] b d # “ x ? o * + k + q “ a % m * s ) u j t y ) w l f e @ t u p z t ^ c a l k j % z a / b w + [ l R ( v l q = e l s d o # s g p l d v } b n m e t s i u e + w + * c = < }

Key Takeaway Points • Generally agreed that two processes are involved in visual search (parallel & serial), though recent neuroimaging data suggests otherwise – substantial overlap in brain areas involved • Different visual features are processed independently • Speed of visual search depends on set size and similarity of targets to distractors • Perceptually grouped objects will be selected or rejected together; grouping probably takes place prior to attentional ‘enhancement’

Posner’s paradigm

Posner’s paradigm

Posner’s paradigm

Posner’s paradigm •

Posner’s paradigm

Posner’s paradigm

Posner’s paradigm

Posner’s paradigm •

Posner’s components of attention • Three components involved in visual attention: – Disengage attention from a given stimulus – Shift attention from one stimulus to another – Engage attention on a new stimulus

Processing Components of Attention (Posner & Rothbart) • Alerting (NE) • Orienting (ACh) • Executive (DA)

Dual Task Performance • Relevant to processing capacity • Interference methodology a useful tool to determine whether two tasks share resources • What determines degree of interference? – Task similarity – Task difficulty – Practice/expertise

• Sensitivity (d') to auditory and visual signals as a function of concurrent imagery modality (auditory vs. visual). Adapted from Segal and Fusella (1970).

Multiple-resource Theories • Wickens (1984). A proposed dimensional structure of human processing resources. From “Processing resources in attention” by Wickens, C. D. in Varieties of Attention edited by R. Parasuraman and D. R. Davies © 1984 by Academic Press. Reproduced by permission of Elsevier.

Norman & Shallice • Three levels of functioning: – Fully automatic processes, controlled by well-learned schemas – Partially automatic processing, controlled by contention scheduling – Deliberate control by a conscious, supervisory attentional system

Summary: Important Concepts • Limited-capacity for informationprocessing (information bottleneck) leads to selective attention • Attentional acts take time and effort • Attentional control re: goals and plans • Automatic vs. Controlled processing • Attention and consciousness