Attention Flashcards
Bottom-Up Attention
Passive modes of attention
- Alertness and arousal
- Reflexive attention (E.g. towards a bolt of lightning)
- Spotlight attention and visual search (E.g. can only attend to what falls within the fovea)
Top-Down Attention
Active modes of attention
- Selective attention (E.g. you choose whether to listen or look at something)
Retina
For the human eye, this is made up of photoreceptor cells and can be broken down into two main areas:
- Fovea (more cells and most of them are cones)
- Parafovea (less cells and most of them are rods)
Eye Movements
We move our eyes 3 times per second
Have been studied for over 2000 years
Examples: Aristotle, Crum, Brown
Our eyes do not see like we think they do…
Acuity drops off as something appears further from the centre
We build up a view of image by amalgamating snapshots
Limits on how we encode information means that what we actually percieve is a lot fuzzier than what we see
Saccade
A rapid movement of the eye between fixation points
Saccades can least up to 50 ms, meaning we can be ‘blind’ for 3 hours of the day
Saccadic Suppression
We do not percieve our own saccades
This happens to suppress the motion blur during the saccades (the eye can travel up to 900 visual degrees per second)
It happens so that we can percieve a stable world
Overt Attention
The focus of attention is what the fovea is currently looking at (arguably)
- Attended info = information in or around the fovea
- Unattended info = everything else
Overt Attention:
- Using your fovea
- Slow - around 3-4 saccades per second
Covert Attention
This is faster than overt - 50 ms to shift
Helmholtz (1867)
- We can enhance perception if we focus our attention on a location in the visual field
- However, this comes at the expense of other areas of the visual field
Attention
Two primary themes characterise attention:
1) Capacity limitation
2) Perceptual gating (selection)
Attention - Capacity limitation
Our limited ability to carry out various mental operations at the same time needs a way to prioritise information
Attention - Perceptual gating (selection)
Conscious perception is always selective, but selection is not always conscious
Focused Attention
A.k.a. Selective attention
Selectively attend to certain stimuli in our environment while ignoring others
Present 2 or more stimuli inputs, instruction to respond to just one
Divided Attention
A.k.a. Multitasking
Ability to undertake several tasks at once
Present at least 2 stimuli inputs, instruction to respond to all
Attention Modalities
Vision
- Limit on how much we can take in, because things in environment placed in different spatial location
Auditory
- Streams of sound from different locations
- Cannot listen to all at once
- Can selectively listen (Cocktail Party Effect)
Focused/Selective Auditory Attention - Welford (1952)
- Presented 2 signals in rapid succession
- PPs make speeded response to both
- Reaction time to second stimulus depends on how close it is presented to first stimulus
- The closer the presentation, the slower the reaction
Welford viewed this as support for:
- What we call a bottleneck (early selection) because processing of one stimulus must be completed before processing of next one can begin
- A central limit on human processing capability
Focused/Selective Auditory Attention - Cocktail Party Phenomena
How can we focus attention onto one conversation in a crowded room?
Research in this area was initiated by Cherry (1953) who was interested in the cocktail party phenomena
Focused/Selective Auditory Attention - Cherry (1953)
Cherry’s Cocktail Party Effect (1953)
Shadowing task
- Dichotic listening procedure - repeat aloud a message they were told to attend to
PPs were able to:
- Filter out the unshadowed message with little information remembered about this message
Process the unshadowed physical characteristics (intensity, gender, location)
PPs were not able to:
- Detect the meaning of the second stream
- Detect if the second stream was a foreign language or reversed speech
- Repeat any words
Broadbent (1958)
Testing the bottleneck
- Dichotic listening procedure - 3 digits presented to one ear at the same time as another 3 presented to the other ear
PPs could recall numbers ear by ear better than in pairs
Suggested that the stimuli are accessed in parallel by a sensory buffer
- Buffer filters stimuli on the basis of the physical characteristics
- The other input remains in the buffer
- (Broadbent’s Filter Theory of Attention, 1958;1971)
Broadbent’s Filter Theory of Attention (1958;1971)
Attention as an early selection process
What does attention do?
- It allows us to selectively process information
- To filter out irrelevant information
- Argues that we cannot identify or process something without attention
Evaluation:
- Filter theory is based on physical properties and therefore is rather inflexible
- Gray & Wedderburn (1960)
Attenuation
Sometimes unattended things are processed
Where the filter occurs depends on task demands (physical cues, syllabic pattern and specific words moving on to analysis of individual words, grammatical structure and meaning)
Sometimes this means that unattended items leak through the filter as they are processed enough to reach the threshold of conscious awareness
Treisman (1964)
Attentional Competing Hypothesis
Early Selection - physical characteristics of messages are used to select one message for further processing and all others are lost (Broadbent, 1958)
Attenuation - physical characteristics are used to select one message for full processing and other messages are given partial processing (Treisman, 1964)
Late Selection - all messages get through but only one response can be made (Deutsch & Deutsch, 1963)
What is visual attention?
Attentional Spotlight:
Focused visual attention within a small region of the visual field but not outside the beam of attentional spotlight (Posner, 1980)
Zoom Lens:
Attention is directed to a given region of the visual field, the area of focal attention can be increased or decreased depending on task demands (Erikson & St. James, 1986)
Attention and Selection - Implication
We are only ‘aware’ of what we attend to
- How many things can we attend to?
- Inattentional and Change Blindness
Inattentional Blindness
What we don’t attend to we are not aware of
Mack & Rock, 1992; Simons & Chabris, 1999
Typically, things such as transients can capture visual attention - but if these resources are fully in use and there are other transients, things may be missed
Change Blindness
If we cannot identify things without attending to them AND attention is a limited resource, we might not be able to spot ‘changes’ between scenes unless attending to them
Clearly, one way of spotting for changes is by changes in luminence (transients) - Change blindness gets past this by presenting an interweaving field between images
Are change blindness and inattentional blindness the same, as they are both forms of blindness?
Resnick (2000) - They are related but different
- CB involves spotting transitions while IB involves identifying something that is “irrelevant” to the task
- CB suggests that there is a failure of Visual Short Term Memory (VSTM) which enables us to compare between scenes (this is irrelevant for IB)
- CB suggests that we might have a limit in the number of items we can hold in VSTM
Visual Short Term Memory (VSTM) - Luck & Vogel (1997)
Measured capacity of VSTM (they called it visual working memory):
- 1 - 12 colour patches shown for 100ms; then blank for 900ms; then shown again for 2000ms
- In one condition there is a verbal load (just to make sure participants are not verbalising the stimuli)
- Capacity = Approx. 4 items
They also tested if capacity depended on objects or features:
- They asked PPs to look for:
a) Change in orientation, b) change in colour and c) change in either (conjunction) - There was no difference in performance - this suggests that VSTM capacity is for objects, not features
VSTM and Change Blindness/Detection
CB and change detection tasks seem to show a clear limit in the information we can hold in VSTM
There is a limit to what we can ‘hold’ across a temporal gap
Limits of Attention
Attention is limited in capacity
It appears that we can “attend” to a small number of areas at the same time
So our idea of what the world is like is very much incorrect
What does covert attention do?
Covert attention is when we attend somewhere or to something without moving our eyes
Acts as a filter - selects stimuli for further processing
Is limited in capacity - it appears that whether the resource can be divided up depends on the task demands
