Mechanisms of selective and divided attention Flashcards
What is attention? - Sternberg 1999
Attention acts as a means of focusing limited mental resources on the information and cognitive processes that are most salient at a given moment
Describe attention as a mental process
Concentrating effort into a stimulus or a mental event (thought)
- Forcing yourself to pay attention in this lecture is an example
- The means by which we actively process information in the sensory registers (sensation caused by light hitting the eyes, in the case of perception)
Describe attention as a limited mental source
Attention as a kind of fuel/mental energy that powers cognition
•It gets used up when we “pay” attention
•Attention is limited
What is attention for?- Selection
We are constantly presented with information from the external world
- Audition: Numerous overlapping sounds simultaneously reach your ears. The busy street; the conversation in the noisy pub
- Vision: complexity and information overload characterize most visual environments
- Your own thoughts: Even what you are thinking competes for your attention…Our attentional capacity is severely limited:
There is only so much we can attend to at one time
Effective selection of information is critical to functioning
Division
Most things you do during the day involve a degree of ‘multi-tasking’
•Writing notes while listening
•Walking and having a conversation
•Watching TV while on the phone
•Listening to music while studying
•Various factors impact on our ability to divide attention Effectively dividing your attention is also critical, as is knowing the limitations
What is selective attention?
how’s it studied?
what does it demonstrate?
focusing all of our attention on one task
present 2 or more stimuli and instruct to attend to one of them
our ability to select, and the fate of unattended stimuli
what is divided attention?
hows it studied?
what does it demonstrate?
sharing your attention between tasks
present ppts with multiple stimuli and instruct to attend to all
the processing limitations of attention
divided attention: task similarity
Specificity of Resources: Allport, Antonis & Reynolds (1972)
Presented participants with a list of words through headphones into one ear.
Task: Shadow these words
Simultaneously: Presented them with a second list.
Later on, memory tested for items for second list
The specificity of Resources: Allport, Antonis & Reynolds (1972) - conditions
The second list presented to the other (unattended) ear.
The second list presented visually on a computer screen.
The second list consisted of images presented visually on screen
Requirements similar, but task similarity varied
Hear words + hear words = high similarity
Hear words + see words = less similarity
Hear words + see images = low similarity
Modality specific resources: Most interference should come from condition 1, and least from condition 3
.General pool of resources: performance should be similar in all three
Found: Most interference in condition 1; followed by 2, followed by 3
Divide attention : practice
Spelke, Hirst & Neisser (1976
Difficult tasks can become less attentionally demanding through practice
Spelke et al. (1976) trained their participants (e.g., gave them practice) on two tasks that are hard to combine.
Two students were trained for 5 hours per week over a 4 month period
Task: read a story for comprehension while also writing dictation.
This was initially really hard, but after 6 weeks they could perform the task very well
divided Attention, Practice & Automatic Processing
If you do a task enough times, it feels less demanding. There’s a psychological reason for that.
- Practice decreases resource demands by diminishing the need for moment-by-moment task control
- Controlled tasks draw more attention than uncontrolled tasks
.•With practice a person approaches a task with a well learned sequence of responses that they have done in the past
•A ‘routine’ like this becomes automated and no longer needs to be supervised or controlled and therefore requires fewer resources
What Makes a Process Automatic? Posner & Snyder (1974; 1975)
A process is automatic if it meets the following criteria:
- It occurs unintentionally
- It occurs unconsciously(outside of awareness)
- It operates without depleting the resources of attention
What Makes a Process Automatic? - Logan 1988
a task becomes automatic when practice changes it so much that it relies on knowledge stored in long-term memory
attention & Automatic Processing
- the effects of automacity
Automatic processes are uncontrolled, take little cognitive effort (attention) and therefore difficult to inhibit.
Not always beneficial!
Whats the stroop interference
Stroop Interference:
Show participants colour words, each printed in a different ink
Task: name the colour of the ink
Typical finding:
Facilitation when the ink and colour word match
Interference when they do not match.
two conditions in the stroop task
Congruent condition and the Incongruent (conflicting) condition
Mechanisms of Selective Visual Attention
Visual selective attention has been likened to a torch beam (Spatial attention: Posner, 1980).
•Information that falls under the beam is processed with priority
- Information outside of the beam receives far less processing
- Metaphors of spatial attention:
- Spotlight
- Zoom lens
- Multiple spotlights
Change blindness - Rensink . o’Regan and Clark (1997)
Pairs of pictures separated by a brief blank interval
Identical except for some single aspect that is missing in one picture but present in the other
Even with clear understanding of this task, it is very hard
Change blindness - Rensink . o’Regan and Clark (1997)
characteristics
If the change involves something central to the scene, observers may need as many as a dozen alternations between the pictures before they detect the change.
If the change involves some peripheral aspect of the scene, then as many as 25 alternations may be required.
Implications of Change Blindness
Implication:
We see far less of a visual scene than we think we do in the absence of attention
Highlights again the limited capacity of attention: We cannot attend to everything!
These studies demonstrate failure to detect changes we are looking for
Inattentional Blindness
Mack and Rock 1998
Participants presented with a large + for 200ms, followed by a pattern mask
Task: Indicate which bar was longest, using two response buttons
Maintained central fixation throughout the experiment and the + was shown off to one side
Inattentional Blindness
Mack and Rock 1998 - results
Performance at detecting line length: 78% accuracy
But! On trial 4, while the target cross was on screen, the fixation target disappeared and was replaced by a shape (e.g., a triangle, a rectangle etc.).
Immediately after trial
asked if anything different had happened during this trial.
89% of participants reported no change
They had failed to see anything other than the attended + shape
To probe the participants further: told that a shape had replaced the fixation cross.
They were then asked what shape they had seen.
Found: Responses were random
Participants had not seen the shape that had been directly in front of their eyes
Inattentional Blindness
Mack and Rock 1998 - conc and implications
Mack and Rock (1998): as participants were not expecting any shapes to appear they were not prepared - their attention was elsewhere (judging the lines)
- Shapes not seen even though in plain sight
- Implication: What we see is dramatically diminished in the absence of attention
- Again, demonstrates our limited amount of attentional resource
Inattentional Blindness
Mack and Rock 1998 - claims
Mack and Rock (1998): without attention there is no perception
In other words, we don’t perceive things that we aren’t attending to
This is a very bold claim
Can we demonstrate perception in the absence of attention?
Bring back the Muller-Lyer illusion.
Inattentional blindness - Moore and Egeth (1997)
Participants shown displays containing two horizontal lines surrounded by a pattern of black and white dots
Task: Which line is longest?
The first three trials: Background dots were random..
Inattentional blindness - Moore and Egeth (1997) - results
On trial 4 the pattern of dots formed a figure like the Muller-Lyer
Participants did not perceive the dot pattern
How do we know? Asked after the trial to decide which dot pattern there had been from 4 choices. 90% got it wrong.
Finding 1: replicates inattentional blindness
Did the Muller-Lyer configuration influence performance on the line task?
Findings: 95% of participants reported line associated with ‘fins out’ as longer
Inattentional blindness - Moore and Egeth (1997) - implications
Even though participants were completely unaware of the fins, they influenced task performance
Attention may be needed for conscious perception
But perhaps you can unconsciously detect (and be influenced by) patterns in the world in the absence of attention
summary
Attention needs to be able to effectively select important information from the environment.
- What might surprise you is how little you actually perceive outside of the information you are focusing on.
- This demonstrates attention as a capacity limited resource that needs to be selective.
- It also demonstrates the very important relationship between what we attend to and what we actually perceive.
