focused attention
TRANSCRIPT
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Focused Attention
Introduction
Early Research
Broadbent’s theory – the filter model
Treisman’s theory – the attenuator model
Deutsch and Deutsch - the pertinence model
Evaluation of single channel models
Early or late selection Summary
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Introduction
•We are constantly bombarded with stimuli of all sorts, but we usually only aware of a small fraction of it.
•We are able to select some information whilst apparently ignoring the rest. This ability is refered to as focused(or selective) attention.
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Early Research
Perception and Communication (Broadbent, 1958)Experiments by Cherry (1953) and Broadbent (1954)
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•Cocktail party phenomenon (Cherry, 1953)•Dichotic listening tasks•Shadowing
•Messages were processed in a number of stages Early stage- physical properties Later stage- meaning of the message
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Broadbent (1954)- split span procedure
5
6
3
2
4
9
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pair-by-pair V.S. ear-by-ear
Accuracy 20% 65%
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•These are all described as single channel models
•Information is filtered in some way
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Broadbent’s theory – the filter model
Perception and Communication(1958)
The first modern theory of attention and introduced a number of key concepts.
1.Attention has a limited capacity2.The filter
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Broadbent’s theory – the filter model
SENSES
FILTER
SHORT-TERM STORE
LIMITED
CAPACITY
CHANNEL
LONG-TERM MEMORY
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This model is described as an early selection model
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Evaluation of the filter model
•Explain some of the early research findings
•Theory was flawed – does not adequately explain the ‘cocktail party phenomenon’
•Moray (1959) adapted the ‘unattended’ message
so that it contained several references to the participant’s name
•participants noticed their name a third of the time
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Left ear: OB-2-TIVE Dear-4-Jane
Right ear: 6-JEC-9 8-Aunt-2
Participants: OBJECTIVE Dear Aunt Jane
Syllable Phrase
Gray and Wedderburn (1960) presented either different short phrases or syllables to each ear simultaneously
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•Treisman (1964) found that if bilingual participants would frequently notice that the messages in different languages were the same
•Underwood (1974) found that experienced participants performed better than inexperienced participants at detecting digits in an unattended ear (with 67% and 8% success rate respectively)
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•The early studies may not have shown a limit to the participants’ attention but rather a lack of practice of an unfamiliar task
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Treisman’s theory – the attenuator model
Treisman suggested that the filter does not block rejected Information but the information is attenuated.
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SENSES
SHORT-TERM STORE
FILTER
ATTENUATOR
SEMANTIC ANALYSIS
RESPONSES
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Semantic analysis
The information is analysed according to word meaning,grammatical structure and sentence meaning.
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Occasionally some of the rejected,or attenuatted,Information will be analysed if this information is important or highly relevant.
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If the information is attenuated,how do we know that is
important or relevant?
QUESTION
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Treisman suggested that we have”word units”which we use when analysing and recognising sentence.
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These “word units” vary in thresholds.This mean that they
require different intensity of stimuli to activate them.
Your Name
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Evaluation of the attenuator model
Moray (1959)found that participants noticed their names in a non-shadowed ear about a third of the time.
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Gray and Wedderburn(1960)
Dear-4-Jane
8-Aunt-2
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‘Dear Aunt Jane’
Treisman would argue that this is because, at the moment ‘4’ and ’Aunt’ are played,paticipants expect to hear a word like Aunt and it momentarily has a low threshold.
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One of Treisman’s experiments suggest that there is more semantic analysis of the attenuated information than the
model allows.
There is a question of how a filter in the system can make
the decisions about what should and should not be attenuated.
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The pertinence model
• Deutsch & Deutsch, 1963• Norman, 1969, 1976• Late selection• Put the bottleneck of processing information
later than the the attenuator model does.
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The pertinence model
• Suggests that all information is initially processed and that selection only takes place after each input has been analyzed in the memory system.
• Selection for attention is closer to the responses (output) than the senses (input).
• Selection takes place based on the pertinence of the information.
• Information that is most pertinent is most likely to be selected. (relevant / important)
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CENTRALPROCESSOR
PERTINENCE
SELECTED FOR ATTENTION
STIMULUS- ANALYSINGMECHANISMS
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The pertinence model
• The pertinence of information is influenced by factors such as expectations and context (top-down factors)
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MacKay, 1973
They were throwing stones at the bank River / Money
Bank referred to a riverbank
Bank referred to a high street bank
Support for the pertinence model that shows information in an “unattended” message is processed and analyzed.
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The pertinence model• A potentially serious problem of this model is
the the finding that the information from most unattended messages is completely lost.
• Why do participants find it impossible to recall any semantic content?
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Norman, 1969
• The information is stored in short-term memory and is forgotten very quickly.
• Participants could remember the last few words of an unattended message if asked recall them immediately after messages ended.
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Solso, 1979
• The model is uneconomical.• It suggests that all information is
analyzed for meaning, yet most of it would not be required or used.
• Need a very large processing capacity.
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Early or late selection?
• Johnson & Heinz, 1978• There are a number of different stages of
processing for incoming information.• Each of the stages use some of the available
processing capacity.• To avoid overloading our limited capacity,
unattended stimuli are processed at the minimum level required to perform task.
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Johnson & Heinz, 1979
• Asked participants to shadow one set of words while ignoring another set.
Easy condition
man woman
Difficult condition
man
Simple process to separate the two sets of words since the physical characteristics of the voiced differed.
Could not differentiate the two set of words by the physical characteristics alone.
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Johnson & Heinz, 1979
• When given an unexpected memory test of the unattended words, participants recalled more in the difficult condition.
• This seems to indicate that selection can be early if information ca be processed using physical properties (easy), or selection might be late if the information needs more thorough analysis (difficult).
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Evaluation of single channel models
• Doubt whether any simple single channel model can explain the complex processes involved in attention.
• The models of focused attention assume that there is a single processor that deals with all incoming information.
• E.g. we cannot listen to two messages at once.• Dual tasks experiments show that we can do two
messages at once. (driving and talking)
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Summary
• Cocktail party phenomenon• Broadbent (early filter model)
There is a selective filter that blocks out some information through to a limited channel.
• Treisman (flexible filter)Information was not blocked but was attenuated.
• Deutsch & Deutsch (late selection model)Explains much of research evidence but it’s a uneconomical model.
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