Academic journal article Canadian Journal of Experimental Psychology

Response Preparation and Control of Movement Sequences

Academic journal article Canadian Journal of Experimental Psychology

Response Preparation and Control of Movement Sequences

Article excerpt

Response Preparation and Control of Movement Sequencesl

Abstract Two experiments investigated the response complexity effect using elbow extension/flexion movements. In the first experiment, RT for an extension movement was significantly less than RT for an extension/flexion movement. However, this difference in RT was not evident when participants were asked to pause at the reversal of the extension/flexion for approximately 260 ms. The second experiment manipulated the duration of the pause between these movements and also measured the electromyographical (EMG) activity of the triceps and biceps muscles. When the pause was reduced to 75 ms participants were not able to program the flexion portion of the movement at the reversal, forcing them to preprogram this movement; hence, increasing their premotor reaction time.

It has been suggested that a sequence of actions can be programmed in advance of movement initiation (Lashley, 1951). One prediction from this suggestion is that a simple movement will take a shorter amount of time to plan than a more complex movement. This prediction has been tested empirically by measuring the reaction time (RT) required to prepare and initiate movements which vary in complexity. RT is defined as the time between stimulus onset and movement initiation. Typically, it has been found that more complex movements require a greater amount of time to prepare and initiate than simpler movements. The variation in RT was assumed to be due to response programming activity, because the tasks required stimulus identification and response selection to be held constant

Freeman (1907) was possibly the first to measure the relationship between RT and movement complexity. He found that when participants drew geometric figures such as a straight line, a circle, or a pentagon, the RT became longer as the figure increased in complexity. These variations in latency were said to have occurred because of antagonistic muscular tensions originating from anticipation of the necessary movement reversals which occurred in the more complex sequences. However, the most influential researcher to work within the RT/movement complexity paradigm was Franklin Henry. In a series of papers in the 1950s and 1960s, Henry and his co-workers laid the groundwork for his "Memory Drum Theory" (Henry & Rogers, 1960). In this theory, the basis of movement control was likened to the memory drum hardware in the computers of the day. It was suggested that the more complex the movement, the more complicated the memory drum program representing it. This more complicated program takes longer to initiate because: a larger amount of stored information will be needed, and thus the neural impulses will require more time for co-ordination and direction into the eventual motor neurons and muscles. (Henry & Rogers, 1960, p. 450) Henry and Rogers tested this theory by having participants produce either a single key lift response or a key lift response concatenated with movements to targets. They found that the simple movement required less time to prepare and initiate than the more complicated sequence of movements. This phenomenon has since been studied extensively. Various researchers have shown that RT increases with increased movement complexity using such tasks as keystrokes and tapping (Fischman, 1984; Klapp & Rodriguez, 1982; Rosenbaum & Patashnik, 1980), speech (Erickson, Pollack, & Montague, 1970; Sternberg, Monsell, Knoll, & Wright, 1978), and handwriting (Hulstijn & van Galen, 1983; Teulings, Mullins, & Stelmach, 1986). The parameter which appears to be most strongly related to changes in RT in these studies is the number of response elements that comprise the movement. Thus, it is the number of taps or keystrokes, number of stress groups in a sequence of speech, and number of strokes taken in writing a letter which has the greatest impact on the time required to prepare and initiate these responses. …

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