Models & Metrics of Human Executive Control - Progress (10/98~02/99)

---

1) MILESTONES:

Associated milestones will be indicated by letters:

 

A. Effects of practice and switching on concurrent task performance (FY99)

B. Identify multiple loci information bottlenecks by recording brain activity (FY99)

2) RESEARCH OBJECTIVE:

Extend and validate the APEX model of executive control by specifying the role of executive control in cognitive processing and how control failure leads to human error in complex task environments.

3) SIGNIFICANT PROGRESS AND PUBLICATIONS:

A. Practice and Task Switching.

Van Selst, M. V., Ruthruff, E. & Johnston, J. C. (1998). Can practice eliminate the Psychological Refractory Period effect? Journal of Experimental Psychology: Human Perception and Performance (in press).

Johnston, J.C., Ruthruff, E., Van Selst,M, and Remington, R. (1998) The effects of single-task practice on dual-task interference. Presented at the 1998 meeting of the Psychonomic Society.

IMPACT: First solid empirical evidence that extended practice reduces interference in the Psychological Refractory Period Paradigm. However, evidence indicates that the residual interference is consistent with a central bottleneck in processing.

Remington, R.W., Ruthruff, E., & Johnston, J.C. (1998). Assessing the cost of task switching with a three-task paradigm. Presented at the 1998 meeting of the Psychonomic Society.

IMPACT: Demonstrated a cost in switching between multiple tasks even when those tasks are not confusable with each other. Response times were faster when 1) the interrupted task had been performed more recently, and 2) a task was expected. The effects of recency and expectancy were additive, indicating that these two factors affect separate stages in processing.

B. Multiple Bottlenecks.

Johnston, J.C., McCann, R & Ruthruff, E. (1998) The attentional blink does not prevent character identification. Presented at the 1998 meeting of the Psychonomic Society.

IMPACT: Demonstrated that 1) the attentional blink is due to a processing bottleneck that 2) occurs earlier in processing than spatial attention.

4) SIGNIFICANT EXTERNAL LIAISONS:

A. Continued collaboration with Mark Van Selst at San Jose State University investigating the effects of practice and response modality on dual-task interference.

B. Began collaboration with John Gabrielli at Stanford University investigating the brain regions active during spatial attention and dual-task processing.

5) ISSUES:

None.