Week 5 - Historical Origins of Attention

attention

brain’s ability to self-regulate input from environment

2 ways attention is used in psychology

1. sustained attention

2. selective attention

sustained attention

alertness

• related to psychological arousal

• problem of vigilance = performance declines over long watch

selective attention

limited in number of stimuli we can process = attend to 1 stimulus at expense of others

• people = limited capacity systems = don’t treat all stimuli equally

cocktail party problem

Cherry 1953

• how do we follow a conversation in crowded environment

• = pick out 1 conversation from background

• picking out involves processes taking sound energy at ear and translating to understanding

• translation is selective

• what happens to unattended messages? = tested thru dichotic listening and shadowing

dichotic listening and shadowing experiment - Cherry 1953

• 2 passages of continuous speech played to person over headphones

• attend to message 1 and say it out loud as it occurs = shadowing

• ignore message 2

• then asked about contents of message 2

cherry’s findings

unattended channel

• no memory for unattended message

• switch from english to german = not noticed

• switch from male to female speaker = noticed

• reversed speech = something’s weird

• swotch from voice to cps pure tone = noticed

channel

sensory pathway acting as a source of information

conclusions of cherry 1953

only superifical/physical features were perceived (male vs female/voice vs non-voice) but semantic content not analysed (language and meaning)

reasons for cherry’s conclusions

Neisser 1967

• physical features processed preattentively/unconsciously

• meaning requires focal attention

binaural presentation

Cherry - both ears received both messages from same voice - differed only in content = difficult to attend to message 1

• only shadowed one of the messages after 20 repeats of trial

= source localisation in space important cue - phase differences in arrival times at ear

how do we select the attended message

dependent on our ability to localise sounds in space

criticism of Cherry

he was interested in what’s perceived but in experiment he 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

• senses>short term store>selective filter>limited capacity channel>meaning

how does filter theory work

• meaning extracted in limited capacity channel

• filter precedes channel = prevents overload

• all stimuli is briefly stored in short term store

• raw acoustice trace decays quickly if not selected

evidence for filter theory

split-span experiments by Broadbent

• presented lists of digits dichotically = left ear heard 1 part and right heard other

• asked to recall list of numbers in order they were presented (Temporal order) = 3-4 correct - below expected avergae of 6-7

• then asked to recall numbers in whatever order participant preferred = ear-by-ear recall = 6 correct

what do results of split-span experiment show

interaction of short-term store and filter

• ear-by-ear recall needs 1 filter switch

• 5 switches needed for temporal recall

• switches take time = short-term store trace decays

conclusion of Broadbent’s experiment

• attentional selection based on simple physical features - location in space, voice

• extracted preattenively - don’t require access to limited capacity channel

• meaning requires access to limited capacity channel - only extracted if stimulis is attended to

failure of filter theory

Dear Aunt Jane experiment by Gray and Wedderburn 1960 - replicated broadbent’s split-span but with meaningful material = preferred recall followed semantic context not presentation ear

dear aunt jane method

dichotic listening - 2 audios per ear and asked to shadow message played in 1 ear using preferred order recall

• meaningul phrase vs list of numbers but

• words alternated between ears

• right ear = dear - 6 - Jane

• left ear = 3 - aunt - five

• preferred recall order = ‘dear aunt jane’ and ‘3 6 5’

= followed semantic context

how did gray and wedderburn disprove broadbent’s filter theory

• broadbent = only extract meaning in limited capacity channel after filter - since meaning is after filter, filter doesn’t know you were presented meaningful material

• G+W = showed that semantic content/meaning affected recall

Moray 1959

embedded participant’s own name in unattended channel during Cherry’s dichotic listening experiment

• often detected name

• selection based on meaning not consistent with idea that meaning only extracted on attended channel

• disproves filter theory

early vs late selection debate

• early selection - treisman 1961

• late selection, Deutsch and Deutsch 1963 and Norman 1968

disagreed about location and properties of filter

overview of early selection argument

left and right ear > sensory analysis > filter > semantic analysis in long term memory > report

overview of late selection argument

left and right ear > sensory analysis > semantic analysis in long term memory>filter>report

attenuation model - Treisman 1961

• attended and unattended enters sensory analysis then filter

• when in filter signals on attended channel at full strength but signals on unattended channel are attenuated

• in LTM = full semantic activation of attended and only partial semantic activation of unattended

= turning down the volume

how does Treisman differ from Broadbent

• Broadbent’s filter completely blocks unattended stimuli

• treisman’s filter partly blocks/attenuates it

filter in triesman attenuation model

• partly blocks unattended stimuli

• filter biased by context and message salience

• highly salient stimuli (e.g. name) and semantically related material (e.g. dear aunt jane) gets thru filter = shifts attention

evidence for early selection

Treisman and Geffen 1967 - Broadbent’s shadowing experiment but also had to make a manual response whenever people heard a particular keyword

• % correct detections higher on shadowed channel but not zero on unattended channel

• = filter attenuates stimuli instead of blocking them

criticism of early selection

filter needs to respond to semantic context and distinguish related from unrelated stimuli = too complex?

• late selection suggests simpler alternative

late selection

filter is located after LTM = all stimuli accesses LTM

• need to pass filter for awareness

Norman 1968 - late selection

• to be aware of stimuli and report it back requires activation of LTM

• multiple sources of activation - bottom-up and top-down selection

• bottom-up = stimulus driven

• top-down = by pertinence/relevance to task

• need both kinds of activation to get thru filter or decays

• activation can happen while unaware

evidence for late selection - McKay 1973

dichotic listening with shadowing

• shadow = ambigious sentence with 2 alternative interpretations

• unattended = keyword related to 1 of the alterantives

• then did recogition test about phrases heard

= recognition biased by previous shadowing task

Von wright, anderson and stenman 1975 - late selection evidence

dichotic listening task + classical conditioning

• condition - specific word + shock = galvanic skin response

• shadow task - conditioned words played in unattended channel

• = GSR to conditionded words and generalised to related words in same category

= semantic activation in absence of attention