Development of task switching and post-error-slowing in children

Abstract

Background: Executive control processes such as task switching and error processing have been shown to change with age. The present study explored from a developmental perspective whether shared or different mechanisms underlie these processes.

Methods: The sample included 180 children (30 in each of the six age groups from 6-11 years) who were required to perform two different tasks: identification of a digit, or counting the number of digits. We computed switch costs as a function of response-repetition, stimulus-response (S-R) compatibility, and post-error-slowing. We also analyzed reaction time distributions.

Results and discussion: The results showed a switch cost in the response-repetition condition, with a reduction in switch cost between 7 to 8 and 9 to 10 years of age, and an S-R compatibility effect in 6 to 9 years old children. Reaction time (RT) distributions showed that the decrement in the switch cost is due to the overall decrease in RTs in fast (5th percentile) trials in 9 to 11 year olds, and slow (95th percentile) trials in 7 to 8 and 9 to 11 years old children, in both the task switch and non-switch trials. A major reduction in RT was found between 9 to 11 years in both the response type and S-R compatibility type conditions. RT distributions for post-error trials revealed that the large decrement seen in 7 to 8 and 9 to 10 years old children is primarily due to the sudden decrease in RTs in the fast and slow trials respectively. The developmental pattern of error processing was similar to one component of task switching (switch cost of the response-repetition condition), indicating that inhibition could be a common mechanism underlying both the processes. However, the failure to maintain task set was found only with task switching.

Conclusion: The development of task switching and error processing is not gradual. The developmental pattern of error processing is similar to that of the switch cost of the response-repetition condition in task switching, indicating that inhibition could be a common mechanism underlying both processes. The present results have implications for theories of executive control.

Figure 1

Example of the stimuli used in the study.

Figure 2

Response latencies as a function of the task repetition/switch, the response repetition/switch, and the S-R compatibility/incompatibility for all the six age groups. (TR = Task-Repetition; TS = Task-Switch; RR = Response-Repetition; RS = Response-Switch).

Figure 3

Mean reaction time (+1SEM) of the 5^th percentile (fast trials) for the task switch and task non-switch conditions for all the six age groups.

Figure 4

Mean reaction time (+1SEM) of the 95^th percentile (slow trials) for the task switch and task non-switch conditions for all the six age groups.

Figure 5

Mean reaction time (+1SEM) of the 5^th percentile (fast trials) for the response switch and response repetition conditions for all the six age groups.

Figure 6

Mean reaction time (+1SEM) of the 95^th percentile (slow trials) for the response switch and response repetition conditions for all the six age groups.

Figure 7

Mean reaction time (+1SEM) of the 5^th percentile (fast trials) for the S-R compatible and S-R incompatible trials for all the six age groups.

Figure 8

Mean reaction time (+1SEM) of the 95^th percentile (slow trials) for the S-R compatible and S-R incompatible trials for all the six age groups.

Figure 9

Switch costs (+1SEM) as a function of the response repetition/switch and the S-R compatibility/incompatibility for all the six age groups. RR = Response-Repetition; RS = Response-Switch; SR = Stimulus-Response

Figure 10

Post error slowing (+1SEM) of all the six age groups.

Figure 11

Mean reaction time (+1SEM) of the 5^th (fast trials) and the 95^th percentile (slow trials) for correct trials immediately following an error for all the six age groups.