week 5 early and late attention Flashcards
The Meaning of “Attention”
-Brain’s ability to self-regulate input from the environment
-Used in two senses in psychology:
I. Sustained Attention (Alertness)
II. Selective Attention
What is 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.)
What is Selective Attention
we are limited in the number of stimuli we can process.
We attend to one stimulus at the expense of others. People have limited capacity systems – we don’t treat all stimuli equally.
The Cocktail Party Problem origin
Cherry 1953
® In a crowed environment, we can ‘pick out’ one conversation from background noise
“Picking out:” processes take sound energy at ear, translate to understanding
Translation is selective (stimuli not all treated equally)
-Cherry was interested in what happens to unattended messages in this scenario
the cocktail party Dichotic Listening and Shadowing
-the headphone play different sound in each ear (Dichotic Listening)
-Cherry asked participants to listen to two simultaneous passages of speech (known as dichotic listening), asking participants to attend to one passage (the attended channel) and ignore the other (the unattended channel).
-attending to a passage by speaking the attended channel out loud (shadowing)
- ask what is the unattended channel about
the cocktail party Dichotic Listening and Shadowing result
Unattended Channel:
-No memory for unattended message
Switch from English to German: not noticed
Switch from male to female: noticed
Reversed speech, play backwards : “something queer”
Switch from voice to 400 cps pure tone: noticed
Conclusion from unattended message
Only superficial (physical) features perceived
Semantic content not analysed (language, meaning)
Preattentive processes vs. focal attention
Preattentive processes vs. focal attention (Neisser, 1967)
Sensory (physical) features processed preattentively
Meaning requires focal attention
Plausible: aware of unattended stimuli only superficially in cherry’s study
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
-biological role is to prevent overload of cognitive system
Filter theory indept
-Attentional selection is based on simple physical features (location in space, voice etc.). Those simple features/properties are extracted (processed) pre-attentively –not requiring access to the limited capacity channel.
® Meaning is extracted in a limited capacity channel, which translates sensory information (sound) into conceptual understanding. This can only be done on the contents of one sensory channel at a time.
® Meaning requires access to the limited capacity channel, and can only be extracted if the stimulus is attended to.
® The selective filter precedes the limited capacity channel, protecting it from overload. There is only one arrow going from the filter to the channel – suggesting that we can only process one thing at a time.
® All stimuli are stored briefly in the short-term store (STS) – which stores unanalysed sensory material. This is known as iconic (visual) or echoic (auditory) memory.
® Sensory information decays quickly if not selected.
Evidence for Filter Theory
Spit span attention
Dichotic digit stream: when people were instructed to recall digits in temporal order, they only got 3-4
digits correct
Ear-by-ear recall: 6 correct (all the digit in one ear to another)
Explaination for Spit span attention
This is because ear-by-ear recall only needs 1 filter switch, whereas 5 switches are needed to follow
temporal order. Switches take time, which decays the short term store trace
The failure of filter theory
“Dear Aunt Jane” experiment (Gray & Wedderburn, 1960)
Split-span experiment with meaningful material
L: Dear Three Jane
R: Six Aunt Five
Preferred recall follows semantic context, not presentation ear
Moray (1959) dichotic task and name
Had participants complete a dichotic listening task, where they listened to two passages of continuous speech (one to the left ear and one to the right). Participants were asked to shadow only one of these passages.
® However, he embedded the person’s name in the unattended channel.
® He found that people often detected the occurrence of their own name on the unattended channel.
Early selection theory (Treisman, 1961)
® Sensory analysis takes raw wave form and converts it into sound, allowing you to distinguish one sound from another.
® Understanding sound involves semantic analysis, where sounds are made meaningful by activating stored knowledge. It is intimately connected with our stored knowledge of the meanings of language in long-term memory
The Early vs. Late Selection Debate
Early:
Sesory analysis > Filter > sematic analysis
Late:
Sensory analysis > sematic analysis > Filter
Attenuation model – a feature of early selection (Treisman, 1961):
® Suggests that the filter partially blocks (attenuates) unattended stimuli – akin to ‘turning down the volume’ on the unattended channel.
® This is in contrast to Broadbent’s model, which suggests that the filter completely blocks unattended stimuli.
® Argued that the filter is biased by context & message salience. Highly salient stimuli (e.g. one’s name) & semantically related material (e.g. Dear Aunt Jane) get through the filter, shifting attention
Evidence for early selection (Treisman & Geffen, 1967):
® Got people to perform a dual task (doing two things at once) – a shadowing task and a detection task. The word tap was embedded in unpredictable places in both the shadowed and ignored passage.
® This method got people to indicate what they perceived as they perceived it (rather than at the end), avoiding the methodological issues in Cherry’s procedures which confounded perception & memory.
® Found that the percentage of correct detections was higher on the shadowed channel, but was not zero on the unattended channel. This is consistent with the
idea of a filter that attenuates unattended stimuli instead of blocking it altogether
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
- top-down, selection by “pertinence” (relevance to task)
Need both kinds of activation to get through filter, otherwise decays
Evidence for Late Selection mckay
Semantic processing on unattended channel
McKay (1973)
Shadow:
“They threw stones towards the bank” (ambiguous)
Ignore:
“ … … … … … river” or “ … … … … … money”, related to the attended channel
-People where unaware of the task.
® McKay found that the semantic content of a word on an unattended channel can bias people’s recognition performance on the attended channel (the unattended word was used to resolve ambiguity on the attended channel). This is only possible if the unattended channel was processed up to the level of meaning
Evidence for late selection: Von Wright, Anderson & Stenman (1975)
® Classically conditioned a galvanic skin response (GSR) to target words. Following this conditioning phase, participants were asked to shadow a passage and to ignore a second unattended passage. Target words has a classically conditioned GSR were embedded in this passage.
® Found that there was semantic activation (GSR) in response to these words, even in the absence of attention. This could only be possible if these words were processed to the level that their semantic category could be identified
