Attention: early vs late selection and load theory Flashcards
To what extent do we process the stimuli we ignore?
Selective attention allows us to focus on some stimuli and ignore others. But to what extent to we process the stimuli we ignore? E.g. other people’s conversations. Where does the bottleneck reside and where does selection take place.
What happens at early selection?
–Irrelevant information is filtered, or attenuated, at perceptual stage of processing.
–Semantic information not processed
– Stimuli gets filtered out early- we never get to know the meaning of it.
What happens at late selection?
–All stimuli is processed to the point of meaning
–Selection takes place at later stage of processing and may involve inhibition
What is ‘the cocktail party effect’?
Colin Cherry (1953)
In a crowded party- you’re able to follow one conversation and block out everything else
Demonstrating early selection
Explain the Dichotic Listening Task
(introduced by Colin Cherry, 1953)
- Present different messages to each ear using special headphones
- Subjects attended one ear and ignored the other
- Repeat attended message out loud - shadowing
What are the results of the Dichotic Listening Task?
- Participants shadowed the attended message easily (even though volumes were the same- dichotic
- When asked about the unattended message:
–Physical characteristics (e.g., sex of voice, large changes in pitch) usually reported.
- Rarely noticed when unattended message was in foreign language or reversed speech.
- No content remembered even when the same word was presented 35 times!
- This was taken as evidence for early selection
Broadbent’s Filter Theory (1958)
An early-selection model - filtering occurs before incoming stimuli are analyzed to the semantic level (e.g. surface features but not meaning analysed)
Filtering occurs before semantic analysis
Only attended message is going in for greater analysis and memory
What does the flow diagram of Broadbent’s Filter Theory (1958) look like?
Messages > sensory store > filter >detector > memory
(between filter and detector is the attended message)
Explain the parts of the filter model
Sensory store: Holds incoming information for a short period of time
Filter: Analyzes messages based on physical characteristics like tone of voice, pitch, location of stimulus (which ear)
Detector: Information is processed to determine meaning
Short-term memory: Holds information for general processing
Problems with early selection
List 3 studies
Moray (1959) - Subjects heard their name in the unattended stream
Treisman (1960)- Bilinguals influenced by unattended stream if it is in second language
Gray & Weddeburn (1960)-
- One ear said dear 7 Jane and the other said nine seven six
–Response should have been “Dear 7 Jane”
–But subjects said “Dear Aunt Jane”
This implies they were processing it semantically and understanding the meaning of the words before filtering it out
Treisman’s attenuation model
- Still an early-selection theory
- Key modification to filter theory:
Unattended messages attenuated (reduced down) rather than lost completely
How does this explain “breakthrough”?
- Words need to meet a certain threshold of signal strength to be detected
- Thresholds for certain words lowered …so more easily detected
Eg. Threshold for own name would be lower and words primed by context (boat) has quite a low threshold. More unusual words have really high thresholds (Rutabaga).
The dictionary unit at Treisman’s model contains words, each of which has a threshold for being detected. What does the graph show about these 3 words?
The person’s name has a low threshold, so it will be easily detected. The thresholds for the words rutabaga and boat are higher, since they are used less or are less important to this particular listener.
Late selection models:
1. what happens if you process everything?
2. where are attended and ignored inputs processed?
- If you process everything you get a semantic meaning of everything. Decision making is based on the meaning.
- Both attended and ignored inputs processed to stage of semantic (meaning) analysis
Late selection model:
1. where does selection take place?
2. what is selection based on?
- Takes place at a higher stage of processing
- Based on analysis of which input is most important/ demands a response
What 3 things can late selection models explain?
- Mackay (1973) Dichotic Listening
- Response competition interference
- Negative priming
- MacKay (1973) Dichotic Listening
- Attended stream: Ambiguous sentence
- Unattended stream: Biasing word
- Gave people a sentence which was quite ambiguous - 2 meanings
- If “money”, “bank” was more likely interpreted as financial institution
- People were processing the meaning of words.
- The unattended word is influencing the attended word
- Response competition interference (e.g. Eriksen & Eriksen (1974)
Task and Result
Task:
- search line for K or P
- ignore letter presented above or below line
- Incongruent distractor in irrelevant location slows RTs
- Distractor identity processed
- People can be more distracted if the distracter is incongruent
- Negative Priming - Tipper & Driver (1988)
Task and Result
Negative priming: Responses to previously ignored stimuli are slowed.
Task:
Categorise red stimuli, ignore green. They were shown either images or words and told to ignore one.
Result:
Responses to word slowed when preceded by semantically related IGNORED picture
- Slowed down by mouse if they were shown a dog. This dog has been semantically categorised as an animal and then been inhibited.
- Suggests ignored stimuli is semantically categorised…and inhibited
Lavie’s Load Theory
- BOTH early and late selection are possible
- The stage of selection depends on availability of perceptual capacity…
…which in turn depends on the perceptual demands(or “load”) of the task stimuli.
The amount of capacity you have spare depends on what you’re doing
Load theory:
Is perceptual capacity limited- Yes or No
Yes
Load theory:
What do tasks with higher perceptual load and low perceptual load do?
High perceptual load: exhaust capacity
Low perceptual load: leave spare capacity
Load theory:
What happens to irrelevant distractors during high and low perceptual load?
High perceptual load:
Irrelevant distractors are filtered or attenuated at early, perceptual stage
(Early selection)
Low perceptual load:
Irrelevant distractors are processed
(Late selection)
Load Theory: High vs Low perceptual capacity
High load:
If you’re doing a task where theres loads to process- distractors get pushed out
Low load:
If you’re doing a task with low load, the other things can also fit through
Evidence supporting Load Theory
Behavioural measures of distraction:
- Response competition effects found under low load
- Reduced or eliminated under high load
- Making the task harder- distractors were blocked out and this is high load.
RT for high load was much higher than low load - Similar effects found with other measures
- E.g. Irrelevant distractor measure
low load- really slowed down
high load- weren’t slowed down
Evidence supporting Load Theory:
Inattentional blindness- S+C
Based on “Gorillas in our midst” study by Simons & Chabris (1999)- watching basketball and not noticing gorilla walking through
Evidence supporting Load Theory:
Inattentional blindness- Cartwright Finch & Lavie (2006)
6 trials – unexpected stimulus on final trial
Had people search for a letter and on the last trial they showed something unexpected
In Low Load- nearly everyone noticed it
In High Load- many people didn’t notice it
Evidence supporting Load Theory:
Neuroimaging evidence- Schwartz et al. (2005)
Task and Results
Task:
- Low load: Detect red cross
- High load: Detect conjunction (e.g. yellow upright)
- Told to ignore background
They were measuring peoples response in visual cortex
Results:
High perceptual load reduces visual cortex response to background
Supports the idea that sometimes when were not attending to something, were not taking in stimuli as much. Practical applications- if visual cortex isn’t seeing something can you be blamed for not seeing something.
Evidence supporting Load Theory:
Neuroimaging evidence- Bishop et al., 2007
High perceptual load reduces amygdala response to fearful faces
amygdala- fear/ emotional processing
Part of your brain thats processing threat is not responding to threat
Implications for individual differences
- what does efficiency of selective attention depend on?
- what do individuals with increased perceptual capacity need?
Efficiency of selective attention depends on availability of perceptual capacity.
Individuals with increased perceptual capacity need increased load to avoid distraction.
Implications for individual differences:
Capacity differences associated with…
–Autism
–Age (children and older adults have reduced capacity)
–Video game experience
Implications for individual differences: Green & Bavelier (2003)
Video game players remained distracted under high load
People who don’t play video games were less distracted in high loads
