关键词: 转换加工, 转换代价, 内源性准备, 外源性调节, 前瞻性记忆效应

Abstract: Switching process is an important aspect of executive control. The process is presented as controlling switching course between two tasks which compete the same cognitive resources in working memory. The course of switching involves both endogenous preparation without an external stimulus and exogenous adjustment in response to the external stimulus. But what is the general way to deal with information is not clear.
A “Task—switch” paradigm was used in this study to investigate the switching process in behavioral experiments. Tasks consisted of a simple classification of Chinese words (noun /verb) or digits (odd /even). For each task, a stimulus picture consisted of a background, one-word Chinese and a two-digit natural number. The task to be performed was indicated by the color of the background (If the color is red, the task is a digit task, and if it is blue, the task is a Chinese-word task). We explored the switching process under foreknowledge conditions in experiment 1. Participants performed two tasks consecutively (task one and task two) that were either the same (task repetition) or different (task switch), and there were three blocks for both task repetition and task switch. All the blocks were presented by the sequence of ABBAAB. In experiment 2, we studied the switching process under no-foreknowledge condition. There were six blocks of stimulus and each block mixed with the trials of task repetition and the trials of task switch randomly. All the blocks were presented in a quasi-random sequence. The presentation (version 0.81) was used to compile the experimental procedures and the 17 inches (1024×768) Dell monitor was used to display stimuli. Thirty healthy and right-handed undergraduate students (12 men and 18 women) from the Capital Normal University participated in the experiments 1 and 2 respectively. The students’ eyesight or corrected eyesight was normal, and their ages ranged from 19-24 years (averaged:20.03). A repeated measure ANOVA was performed to analyze the data.
The results suggested: 1.The task repetition and task switch were different courses. The time of task repetition effect was significantly longer than that of task switch effect, under the condition of foreknowledge or no-foreknowledge; 2. The hypothesis was confirmed that endogenous preparation and exogenous adjustment were two different courses of switch process; 3. Under the conditions of foreknowledge task repetition, foreknowledge task switch and no-foreknowledge, the influence of task two on task one was different. There was a prospective memory effect in this course.
Comparing the results of experiments 1 and 2, we conclude that the general way of the switching process in dealing with information as an important aspect of executive control is that under the condition of foreknowledge, switching process beginning with endogenous preparation after task one is clear, and is accomplished via exogenous adjustment after task two is presented. In the case of no-foreknowledge, however, switching process can be accomplished only by relying on the exogenous adjustment

Key words: switching process, switching cost, endogenous preparation, exogenous adjustment, prospective memory effect