What did William James (1890) say attention was?
“Everyone knows what attention is. It is the taking possession of the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought”
What did Harold Pashler say attention was?
“No one knows what attention is. There may not even be an “it” there to be known about (although of course there might be).”
What study did Cherry (1953) conduct?
- Dichotic listening
- ‘Shadow’ the message to one ear and ignore the message in the other ear
- Two different passages being spoken in each ear
- More likely to focus on one message
What did Cherry find in his study?
- After shadowing, participants were asked about the semantic content of the ‘unattended’ message
- They didn’t notice if the language changed from English to German or if the speech was reversed
- They could report the gender of the speaker and whether the message contained speech or non-speech
What did Cherry conclude?
- People process ‘unattended’ information ONLY to the level of physical features
- No semantic information is available from the ‘unattended’ message
- Known as the cocktail party problem
What is the Early selection model (Broadbent 1958)?
- Filtering occurs at an early stage of analysis (prior to meaning)
- Brain filters out any message not having appropriate ‘physical’ characteristics
- Senses – sensory buffer – selective filter – limited capacity processor
What is Moray (1959) the two alternative forced choice procedure?
- Even a word repeated 35 times was not recognised
- But if that word was the participant’s own name, they often would report hearing it (only for one third of participants)
What is the split span experiment?
Gray and Wedderburn (1960)
- ‘Split-span’ experiment
- 40% reported by ear
- 60% reported by meaning
- So it seemed like the ‘unattended’ message was processed for content after all (at least by 60% of people)
What is the Late-selection model?
- Deutsch and Deutsch (1963)
- All inputs are encoded and analysed in parallel to a semantic level
- Selective filtering only occurs at the stage of conscious awareness
- Senses – unconscious semantic processing – selective filter – conscious attention
What did Corteen and Dunn (1974) do with electric shocks?
- Training: City names paired with electric shock. Subjects sweat when they hear any city name.
- Test: Shadow one ear and ignore other. Press a button if you hear a city name in either ear.
- Measures: galvanic skin responses (GSRs) and button presses to city names.
What did Corteen and Dunn (1974) find in their shock study?
- 42% of city names in ‘unattended’ ear elicit a GSR (30% for non-shock-associated city names)
- On only 2% of these trials did the participant make a button press response
- Different measures of awareness of ‘unattended’ stimuli give different results
What is the Attenuator model -Treisman (1964)?
- Unattended information is ‘attenuated’ (not filtered out completely)
- All inputs are analysed for meaning (but some signals are now weaker than others)
- The dictionary analysis units act as the final filter
- Different words have different trigger thresholds (e.g. your name has a low threshold)
- Senses – attenuating filter – dictionary analysis filter
What did Neisser and Becklen (1975) find when looking at video targets?
- Monitoring one video for targets leaves people unaware of events in the unmonitored video
- People incredulous when told
What did Simons and Chabris (1999) do in the gorilla experiment?
- Around 50% of people fail to notice the gorilla when attending to the team in white T-shirts
- More likely to notice if carrying out an ‘easy’ task than if carrying out a ‘hard’ task
- More likely to notice gorilla if attending to team in black T-shirts
What did Dalton and Fraenkel (2012) do in the auditory gorilla experiment?
- 70% of people fail to notice the auditory gorilla man when attending to the women’s conversation
- 90% notice him when attending to the men’s conversation
- All participants but one notice him in the full attention control
What are the problems with video tasks?
Eye movements related to attended events might reduce acuity for unattended events
What did Rock and Gutman (1981) do when looking at coloured shapes?
- Attend to shapes in one colour and rate their pleasant/unpleasantness
- People unable to recognize shapes in ‘unattended’ colour (even if familiar)
What is negative priming? (Tipper 1985)
- Negative priming is a slowdown in response speed and an increase in error rate when responding to an object that had to be ignored previously
- In his study, participants were found to name objects more slowly when they had to ignore the same objects just before.
- Participants see a prime stimulus: a red and a green object on top of one another (i.e., superimposed). They need to remember the red one for a later memory test, while ignoring the green one.
- Participants see a probe stimulus, a red and a green object. They need to say the name (i.e., “naming”) of the red object while ignoring the green one.
- Mean time to name probe: 615 ms 677 ms 695 ms 726 ms 746 ms
In defense of Broadbent…
- Lachter, Forster & Ruthruff (2004)
- Maybe attention is sometimes allocated to the supposedly unattended stream
- They term this process ‘slippage’
Perceptual load theory
-Lavie (1995)
- Perceptual system has a limited capacity
- All stimuli are processed automatically until capacity is reached
- High perceptual load in relevant task leaves no spare capacity for processing task-irrelevant stimuli
- Low perceptual load leaves spare capacity which “spills over” involuntarily to the processing of task-irrelevant stimuli
What did Rees et al (1997) do when looking at perceptual load theory?
- increasing “…perceptual load entails increasing the number of items in a display or increasing the processing requirement for the same number of items”.
- fMRI study of perceptual load
- Low load: respond to uppercase words
- High load: respond to bisyllabic words
- IGNORE irrelevant motion in background
- Psychophysics: longer motion aftereffect under low load than under high load
- fMRI: more activity in cortical area V5 (‘motion area’) under low (vs. high) load
Why is evidence so mixed?
1) Use of different performance measures
2) Over-extrapolation of findings
3) Perceptual load varies across tasks
4) Different sensory modalities
