Effect of Practice

• Practice had been seen to improve dual task performance.
• Controlled Processing: When a task requires conscious control and is high in cognitive demand
• Automatic Processing: This does not require conscious control and is also difficult to control consciously. It also uses little processing capacity. E.g. Skilled driver or musician

Stroop Task & Automatic Processing

• The Stroop Task required participants to say the colour a word is written in. The words are presented as other colour names.
• Participants tend to find difficulty in this task as they say the colour written in the word rather than the colour of the text.
• this indicates and provides evidence for the automatic processing of language.

Consistent Mapping Task

• Schneider and Shriffin (1977)
• The participant is given a target, and is presented with serial frames. They must identify when the target is present in a frame.
• Initially, participants had 55% correct performance, however after 900 trials, they reached 90% correct performance. This occurs without any intervention, and leads to the used of only a few cognitive resources.
• An increase in the number of characters in either memory set or distractor had no effect on performance.

Varied Mapping Task

• Schneider and Shriffin (1977)
• The memory and distractor sets are always letters. a letter can be in the memory set in one trial then become a distractor later. The distractor in one trial can also become the target on another
• Results: This is found to be so difficult that the participants don't achieve automatic processing, even with practice.
• In contrast with the consistent mapping task, increasing the number of characters caused a decrease in performance.
• Performance was only successful if distractors were shown for 400msec rather than 120 msec. Performance was still only 50% correct however in contrast to 90% in the consistent task which had faster presentations.

Divided Attention

This is the process of focussing on more than one thing at a time.

Limitations:

• Perceptual: how many things can we attend to at the same time?
• Central processing/executive: dual task performance and capacity limitations.

Theories:

• Multiple Resource: The success of dual task performance depends on whether the tasks require the same processing resources.
• Central Capacity: this depends on the demands of each task on the limited capacity central processor

Factors influencing the success of dual task performance:

• Task similarity: the participant is more likely to be successful if the task involves different stimulus or response modalities.
• Task difference: this does not necessarily mean the sum of the difficulties, but it also concerns coordination and interference difficulties.
• Practice: The demands placed on attentional resources may be reduced if the task or action is practiced. A development takes place from controlled to automatic processing.

Task Similarity

• Stimulus modality: Stimuli that are presented in the same sense modality produced poorer monitoring performance than when they were presented in different modalities (Treisman & Davies 1973)
• Response Modality: An experimental example of this comes from McLeod, (1977) where a tracking task and a tone-identification task were used, and a manual or vocal response was given. The performance on the tracking task was worse when the mode of response was the same as the task, ie manual, than when it was different ie vocal.

Task Difficulty

• The effectiveness of a dual task performance decreased as a task becomes more difficult
• The difficulty refers not only to the demands of each task, but also of the demands of coordinating the two. This can require additional processing resources.
• D'Esposito et al. (1995): Semantic judgement task AND/OR spatial rotation. In the DUAL task condition, fMRI shows significant activity in the prefrontal cortex and anterior cingulate