Cognition - Divided Attention

Divided attention

Divided attention - Doing two things at once. Effectively dividing your attention is critical to normal functioning. 

Why is it necessary?

  • Many experiments have examined our capacity to do two things at once and divide our attention - participants are usually asked to perform two tasks either on their own, or at the same time. It has been found that performance on one or both tasks suffers when they are performed together 

Factors that influence success at dividing attention:

  • 1) Task similarity
  • 2) Task difficulty
  • 3) Practice
  • 4) Automacicity.
  • Dividing attention between cognitive taks is only going to be successful if the sum of the tasks demands does not exceed attentional capacity.
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Lab studies of divided attention - Specificity of

The specificity of resources

  • Some tasks are harder to combine than others - some mental resources seem specialized.

Example 1: Reading whilst listening to the tv - both draw on resources specialized for verbal processing. Listening to the tv is likely to exhaust these resources. Reading performance therefore suffers.

Example 2: Looking at pictures whilst listening to the TV. Picture viewing does not require verbal resources. Therefore the two tasks draw on separate pools of attention and don't compete.

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Lab Studies - Allport, Antonis and Reynolds (1972)

Overall Method

  • Presented participants with a list of words through headphones into one ear.
  • Asked to shadow these specific words.
  • Simultaneously, they then presented them with a second list. Memory was then tested for items in the second list.


  • Second list presented to the other, unattended ear. 
  • Second list presented visually on a computer screen. 
  • Second list consisted of images presented visually on screen.


  • Requirements similar, but task similarity varied. 1) Hear words + hear words = high similarity. 2) Hear words + see words = less similarity. 3) Hear words + see images = low similarity.
  • Task specific resources: Most interference some come from condition 1, and least from condition 3. Found that most followed by 2 and then 3.
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Lab studies - A pool of general resources

  • Interference increases with task similarity. 
  • But, we can still demonstrate interference between unrelated tasks - this suggests that a pool of general (not specific) resources too.
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Lab studies - Identifying General Resources

  • Evidence - Lamble, Kaurenen, Laaski and Summala, 1999.
  • The prediction that unrelated tasks interfere with each other suggests and attentional resource that is general in application.
  • Take away message: No matter what the resource, tasks will interfere with each other if their combined demand for a resource is greater than the amount available - that is, if the demand exceeds the supply.
  • Doing two things at once is harder when the tasks are similar. 
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Lab studies - Task difficulty

Task difficulty - doing two things at once is also harder when the tasks themselves are harder.

Example 1: Skilled driver

  • Skilled driver can probably talk on hands free and drive with no problems.
  • But, weather turns bad reducing visibility - the conversation gets complex (problems arise). 
  • There is a close relationship beteen complexity and attentional demand.
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Attention and Practice - Spelke, Hirst and Neisser

Spelke, Hirst and Neisser (1976)

  • Demonstrated the impact of practice: Trained their participants on two tasks that are hard to combine. 
  • Two students were trained for 5 hours per week over a 5 month period. They were asked to read a story for comprehension while also writing dictation.
  • Found that initially, the task was really hard, but, after 6 weeks, the participants could perform much better. 

Practice = automacicity

  • Practice decreases resource demands by diminishing the need for moment-by-moment task control.
  • Controlled taks draw more attention than controlled 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.
  • It therefore requires fewer resources.
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Automatic processing

What makes a process automatic? 

Posner & Snyder (1974; 1975) said 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.

Typically, a skill only becomes automatic after extensive practice (as demonstrated in Speike et al's '76 reading/dictation study).

  • Logan (1988): A task becomes automatic when practice changes it so much that it relies on knowledge stored in long-term memory.
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Automatic vs Controlled Attention

  • Sometimes, tasks may use a combination of both and so it isn't necessarily a case of black and white. 
  • Moors and DeHouwer (2006) argue that there is no firm dividing line between automatic and controlled processing. 
  • Indeed, most tasks seem to involved a blend of both. 
  • They should instead be viewed as being different ends of a contiuum.
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Attention and Automatic Processing

The effects of automacity

  • However, automatic processes are uncontrolled and are therefore difficult to inhibit.
  • This isn't always beneficial!

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: Congruent (matching) condition; Incongruent (conflicting) condition.
  • Results found a innate desire to read word. Reflects reading as an automatic function.
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Attention Capture: The Orienting Reflex

  • Sometimes rather than voluntarily directing our attention, it is suddenly captured by an outside event.
  • In a quiet room, an unexpected noise grabs your attention and you move your head/eyes towards the source.
  • In vision, you move your eyes or head towards an unexpected movement in your peripheral vision - this is the orienting reflex.

'The reflexive redirection of attention that orients you toward unexpected stimuli.'

  • The cognitive manifestation of this is that you redirect your attention toward something, even if the eyes and body do not actually move (although they usually do too).
  • This process is known as attention capture - which is the spontaneous redirection of attention to stimuli in the world based on physical characteristics.
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Attention Capture: What is O-Reflex for?

  • A location-finding response. 
  • Protects yourself against potential danger.
  • Some of the neural pathways involved correspond to the 'where' (dorsal) pathway. 
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Stimuli that capture attention: Emotional Cues

Cowan (1995) noted two catagories of attention-capturing stimuli:

  • Stimuli that are significant to the organism.
  • Stimuli that are novel.
  • What is significant to you has often some relation to emotions. People are more likely to direct their attention to emotionally arousing stimuli like a snake in the grass.
  • In experiments of selective attention, participants were more likely to detect their name in the unattended channel in our verbal shadowing task.
  • This tells us that emotional or salient stimuli tend to capture our attention. 
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Social and Novel Cues

Social Cues

  • Attention can also be captured and directed by social cues.
  • Noticing where other people are looking (Kingstone, Smilek, Ristic, Freisen and Eastwood, 2003) 
  • We tend to look at what other people are looking at.
  • If the stimulus captured their attention, maybe it is important for us too!

Novel cues

  • We orient our attention toward novel things (when something different occurs).
  • Orienting focuses the organism so it can devote attention to the stimulus if needed.
  • Orienting is a prepatory response: it prepares the system for further voluntary processing.
  • If the stimulus that triggered the orienting reflect occurs over and over again it is no longer novel or different.
  • This process of habituation begins to take over (a gradual reduction of the orienting response back to baseline).
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