Attention (PSYC20007) - Week 5

Attention I. Historical Origins Philip Smith (RB 910) [email protected] Goldstein, ch. 4, pp. 93-98 Norman, ch 2. “Attention” Styles, ch. 2. “Early Work on Attention”  Learning Objectives Global Learning Objective  Understand and...

Attention I. Historical Origins Philip Smith (RB 910) [email protected] Goldstein, ch. 4, pp. 93-98 Norman, ch 2. “Attention” Styles, ch. 2. “Early Work on Attention”  Learning Objectives Global Learning Objective  Understand and explain the main theories, concepts, and findings in selective attention research from the the 1950s until the present  Understand and explain the complementary relationship between theories and experiments in attention research and the way each drives development of the other  Learning Objectives Today's Learning Objectives  Explain what the cocktail party problem is and Cherry's solution to it  Explain the difference between dichotic and binaural listening and what the difference tells us about the mechanisms auditory selective attention  Describe Broadbent's filter theory and why he believed the filter was placed between the short-term store and the limited capacity channel  Explain why the "Dear Aunt Jane" experiment falsified filter theory  Describe the difference between early and late selection theories of attention  Explain why the Treisman and Geffen "tap on the unattended channel" experiment supports early selection theory  Describe the kinds of experimental evidence that support late selection theory and give two examples of experiments that support it  The Meaning of “Attention”  Brain's ability to self-regulate input from the environment  Used in two senses in psychology:  I. Sustained Attention (Alertness)  Related to psychological arousal (continuum from drowsy, inattentive to alert, attentive)  Problem of vigilance: performance declines over a long watch (radar operators, quality control inspectors, etc.)  The Meaning of “Attention” II. Selective Attention  Limited in the number of stimuli we can process  Attend to one stimulus at the expense of others  People as limited capacity systems: don't treat all stimuli equally  “The Cocktail Party Problem” Cherry (1953)  How do we follow a conversation in a crowded environment?  Can “pick out” one conversation from background  “Picking out:” processes take sound energy at ear, translate to understanding  Translation is selective (stimuli not all treated equally)  How to study this process?  Cherry: what happens to unattended messages?  Dichotic Listening and Shadowing Direct attention to Message 1, ignore Message 2 “Dichotic”: “di” (two) + “oto” (ears) “Channel:” sensory pathway acting as a source of information  Cherry's Findings Shadow Message 1, then ask about contents of Message 2 Unattended Channel:  No memory for unattended message  Switch from English to German: not noticed  Switch from male to female: noticed  Reversed speech: “something queer”  Switch from voice to 400 cps pure tone: noticed  Fate of the Unattended Message Conclusions:  Only superficial (physical) features perceived  (things distinguishing voice, non-voice, or male, female)  Semantic content not analysed (language, meaning) Preattentive processes vs. focal attention (Neisser, 1967)  Sensory (physical) features processed preattentively  Meaning requires focal attention Plausible: aware of unattended stimuli only superficially How Do We Select the Attended Message? Binaural presentation (Cherry): both ears receive both messages, same voice, differ only in content Very difficult! Source localisation in space important cue (phase differences in arrival times at ear)  A Criticism of Cherry Interested in what's perceived, Cherry looked at what's remembered Confounds perception and memory May be perceived then forgotten?  Filter Theory (Broadbent, 1958)  Attention acts as a filter to select stimuli for further processing Filter Theory (Broadbent, 1958)  Meaning extracted in limited capacity channel  Filter precedes channel, protects it from overload  All stimuli stored briefly in short term store (STS)  Raw acoustic trace, decays quickly if not selected Evidence for Filter Theory Interaction of STS and filter Dichotic digit stream:  Temporal order: 3-4 correct  Ear-by-ear recall: 6 correct  Filter Switching Times Ear-by-ear recall needs 1 filter switch, 5 switches needed to follow temporal order Switches take time, STS trace decays  Conclusions Attentional selection based on simple physical features (location in space, voice, etc.) Extracted preattentively (don't require access to limited capacity channel) Meaning requires access to limited capacity channel, only extracted if stimulus is attended  Attention II. The Early vs. Late Selection Debate (The 1960s)  The Failure of Filter Theory “Dear Aunt Jane” experiment (Gray & Wedderburn, 1960) Split-span experiment with meaningful material Preferred recall follows semantic context, not presentation ear  Moray (1959) Person's own name often detected on unattended channel Selection based on meaning not consistent with idea that meaning only extracted on the attended channel  The Early vs. Late Selection Debate Disagreement about location and properties of filter  Attenuation Model (Treisman, 1961) Broadbent's filter completely blocks unattended stimuli, Treisman's partly blocks (attenuates) it Like “turning down the volume”  Attenuation Model (Treisman, 1961) Filter biased by context, message salience Highly salient stimuli (name), semantically related material (Dear Aunt Jane) gets through filter, shifts attention  Evidence for Early Selection Treisman & Geffen (1967) % correct detections higher on shadowed channel, but not zero on unattended channel Consistent with filter that attenuates stimuli instead of blocking them  Criticism of Early Selection Complexity of filter: Needs to respond to semantic context, distinguish related from unrelated stimuli – simpler alternative? Late selection: Differs in where filter is located, after LTM instead of before LTM  Late Selection  ES and LS theories agree recognition needs (a) encoding, (b) access to LTM  LS theory: All stimuli access LTM, not sufficient for awareness  ES theory: LTM activation = conscious awareness  LS theory: need to pass filter for awareness Late Selection (Norman, 1968) Bottom-up and top-down selection mechanisms Bottom-up, stimulus driven and top-down, selection by “pertinence” (relevance to task) Need both kinds of activation to get through filter, otherwise decays  Evidence for Late Selection Semantic processing on unattended channel McKay (1973) Shadow: “They threw stones towards the bank” (ambiguous) Ignore: “............... river” or “............... money” Recognition: “They threw stones towards...” (1) “...the side of the river” (2) “... the savings and loan” Recognition biased by previous shadowing task  Von Wright, Anderson & Stenman (1975) Semantic activation in the absence of attention Generalised to other words in category  Conclusions Filter theory explains simple findings, but can't explain semantic processing of unattended stimuli Early selection: explains by attenuating filter Consistent with partial, but reduced processing of semantic targets (“tap'”) Late selection: all stimuli activate semantic representations in LTM, but need to be selected by pertinence to get into consciousness Consistent with indirect measures of semantic processing on the unattended channel