Speed-accuracy tradeoff functions in choice reaction time: Experimental designs and computational procedures

The existence of tradeoffs between speed and accuracy is an important interpretative problem in choice reaction time (RT) experiments. A recently suggested solution to this problem is the use of complete speed-accuracy tradeoff functions as the primary dependent variable in choice RT ,experiments instead of a single mean RT and error rate. This paper reviews and compares existing procedures for generating empirical speed-accuracy tradeoff, functions for use as dependent variables in choice RT experiments. Two major types of tradeoff function are identified, and their experimental designs and computational procedures are discussed and evaluated. Systematic disparities are demonstrated between the two tradeoff functions in both empirical and computer-simulated data. Although all existing procedures for generating speed-accuracy tradeoff functions involve empirically untested assumptions, one procedure requires less stringent assumptions and is less sensitive to sources of experimental and statistical error. This procedure involves plotting accuracy against RT over a set of experimental conditions in which subjects’ criteria for speed vs. accuracy are systematically varied.     

Empirical approaches to information processing: Speed-accuracy tradeoff functions or reaction time

Recently Wickelgren has advocated the abandonment of reaction time research and its replacement with speed-accuracy methodology. This paper takes issue with the speed-accuracy approach and argues that the proposed methodology has little advantage over reaction time studies. Furthermore it is argued that speed-accuracy studies may have severe flaws of their own.     

Speed-accuracy tradeoff and information processing dynamics

For a long time, it has been known that one can tradeoff accuracy for speed in (presumably) any task. The range over which one can obtain substantial speed-accuracy tradeoff varies from 150 msec in some very simple perceptual tasks to 1,000 msec in some recognition memory tasks and presumably even longer in more complex cognitive tasks. Obtaining an entire speed-accuracy tradeoff function provides much greater knowledge concerning information processing dynamics than is obtained by a reaction- time experiment, which yields the equivalent of a single point on this function. For this and other reasons, speed-accuracy tradeoff studies are often preferable to reaction-time studies of the dynamics of perceptual, memory, and cognitive processes. Methods of obtaining speed-accuracy tradeoff functions include: instructions, payoffs, deadlines, bands, response signals (with blocked and mixed designs), and partitioning of reaction time. A combination of the mixed-design signal method supplemented by partitioning of reaction times appears to be the optimal method.     

Correction for fast guessing and the speed-accuracy tradeoff in choice reaction time

In choice reaction time tasks, response latency varies as the subject changes his bias for speed vs accuracy; this is the speed-accuracy tradeoff. Ollman's Fast Guess model provides a mechanism for this tradeoff by allowing the subject to vary his probability of making a guess response rather than a stimulus controlled response (SCR). It is shown that the mean latency of SCR's (μ_s) in two-choice experiments can be estimated from a single session, regardless of how the subject adjusts his guessing probability. Three experiments are reported in which μ_s apparently remained virtually constant despite tradeoffs in which accuracy varied from chance to near-perfect. From the standpoint of the Fast Guess model, this result is interpreted to mean that the tradeoff here was produced almost entirely by mixing different proportions of fast guesses and constant (mean) latency SCR's. The final sections of the paper discuss the question of what other models might be compatible with μ_s invariance.     

Effects of graded doses of alcohol on speed-accuracy tradeoff in choice reaction time

The inconsistency of previous results concerning the effects of alcohol on reaction time (RT) may be related to possible tradeoffs between speed and accuracy. In the present experiment, complete speed-accuracy tradeoff functions were generated for each of five doses of alcohol (0-1.33 ml/kg) in a choice RT task. Such functions permit RT differences resulting from changes in performance efficiency to be distinguished from those due to changes in subjects’ speed accuracy criteria. Increasing doses of alcohol produced a progressive decrease in the slope parameter of linear equations fit to the speed-accuracy data, but did not significantly alter the intercept of the functions with the RT axis. Thus, alcohol reduced performance efficiency by decreasing the rate of growth of accuracy per unit time. A change in speed-accuracy criterion was combined with the decrease in efficiency at the highest alcohol dose.     

Speed-accuracy tradeoff in double stimulation: Effects on the first response

A single-stimulation and two double-stimulation response conditions were compared using explicit payoff matrices to vary speed-accuracy tradeoff. Under accuracy payoff, response latency (RT(1)) to the first stimulus increased as ISI dropped but accuracy remained high and relatively constant. Under speed payoff, RT(1) was only slightly affected by ISI but accuracy dropped as ISI decreased. Transmitted information rates consistently reflected detrimental effects of short ISI. In double stimulation, but not in single stimulation, error response latency exceeded correct response latency. Furthermore, error response latencies were found to be far more variable and more sensitive to changes in speed-accuracy condition than were correct response latencies. Finally, under both speed and accuracy conditions, response latency to the first of two successive stimuli was faster if a response was also required to the second stimulus. Implications of the data for possible models of double-stimulation speed-accuracy tradeoff are considered.     

Speed-accuracy tradeoff in double stimulation: II. Effects on the second response

In the double-stimulation paradigm subjects respond to two successive stimuli. Previous research (Knight & Kantowitz, 1974) showed that a subject's speed-accuracy tradeoff (SAT) strategy interacted with the interval between the two stimuli to determine response performance to the first stimulus. The present experiment examined the influence of SAT strategy on response performance to the second stimulus. Interest focused on effects of SAT strategy upon the psychological refractory period (PRP) effect. If a single mechanism underlies beth first-and second-response performance (e.g., the PRP effect) in double stimulation, effects of SAT upon the second response should be similar to effects upon the first response. Results showed that the PRP effect appeared only when second-response accuracy was stressed. Under speed emphasis double-stimulation second-response latency never exceeded a single-stimulation baseline. This was analogous to first-response latency effects found by Knight and Kantowitz (1974). Response grouping was strongly influenced by SAT strategy and two response-grouping mechanisms were distinguished. Implications of these and interresponse time data for models of double-stimulation performance are discussed.     

Amending limb movements to mechanical perturbations under choice reaction time conditions

This paper examines the amendment of limb movements to mechanical perturbations under choice reaction time conditions. The two experiments reported were designed to examine the question of whether amendment latencies increase under choice conditions using two different choice manipulations. In Experiment 1, choice was manipulated by varying the duration of a mechanical perturbation in a known direction, while in Experiment 2 the strategy was to present perturbations of similar duration but unknown direction. Subjects produced discrete timing responses (700 ms-70 degrees) during which perturbations were interjected on random trials. The results reported reflect the outcome accuracy, the kinematics of the responses and latency of response modifications as a function of the various choice manipulations. The data demonstrated no statistically significant increases in reaction time as a function of choice manipulations. Although latencies did not significantly vary, both experiments demonstrated a significant decrease in response accuracy for the choice conditions. Collectively, the results are discussed in relation to the discrepancies between previous proprioceptive choice reaction time studies, which appear to stem from inconsistencies in both experimental methods and data analysis procedures.     

Response-stimulus interval in choice serial reaction time: Interaction with sleep deprivation, choice, and practice

In choice serial reaction time (RT), Response-to-next-Stimulus Interval (RSI) was varied from 0 to 600 msec in 40-msec steps. In three experiments, RT fell and errors rose as RSI was increased to 480 msec; they remained unchanged thereafter. The effect of RSI on RT was not linear, was reduced by 6- as compared with 4- or 3-choice responding, and was unaffected by sleep deprivation, despite loss of sleep reducing RT overall. The effect of penultimate RSI on RT was similar to that current RSI, but smaller. Two explanations of RSI—response-generated kinaesthetic feedback blocking a “central processor” and a preparatory interval as in warned simple RT—are rejected. Instead, the idea of “relative refractory state” is revived but now, because of the RSI/error finding, biased more towards responding than stimulus reception and encoding. In all three experiments the influence of RSI on RT was reduced with practice. If practice encourages automatic rather than controlled processing (Shiffrin & Schneider, 1977), the prediction is that the former will show less refractoriness.     

Effects of variations in force on fractionated reaction time in simple and choice conditions

The present study examined the effects of force output on fractionated reaction time under simple and choice conditions. 20 subjects were required to react and produce a designated force as soon as possible after a visual stimulus. Five different levels of force were 10, 30, 50, 70, and 90% of the maximum grip strength of the subjects. Analysis showed that reaction time (RT) changed as a function of force in both conditions, with the longest RT occurring at the 70% condition. The same pattern was also evident for premotor time. These findings suggest that the changes in RT with increases in force are mediated predominantly by central rather than peripheral processes.     

Programming strategies for rapid aiming movements under simple and choice reaction time conditions

Increases in reaction time (RT) as a function of response complexity have been shown to differ between simple and choice RT tasks. Of interest in the present study was whether the influence of response complexity on RT depends on the extent to which movements are programmed in advance of movement initiation versus during execution (i.e., online). The task consisted of manual aiming movements to one or two targets (one- vs. two-element responses) under simple and choice RT conditions. The probe RT technique was employed to assess attention demands during RT and movement execution. Simple RT was greater for the two- than for the single-target responses but choice RT was not influenced by the number of elements. In both RT tasks, reaction times to the probe increased as a function of number of elements when the probe occurred during movement execution. The presence of the probe also caused an increase in aiming errors in the simple but not choice RT task. These findings indicated that online programming was occurring in both RT tasks. In the simple RT task, increased executive control mediated the integration between response elements through the utilization of visual feedback to facilitate the implementation of the second element.     

Programming strategies for rapid aiming movements under simple and choice reaction time conditions

Increases in reaction time (RT) as a function of response complexity have been shown to differ between simple and choice RT tasks. Of interest in the present study was whether the influence of response complexity on RT depends on the extent to which movements are programmed in advance of movement initiation versus during execution (i.e., online). The task consisted of manual aiming movements to one or two targets (one- vs. two-element responses) under simple and choice RT conditions. The probe RT technique was employed to assess attention demands during RT and movement execution. Simple RT was greater for the two- than for the single-target responses but choice RT was not influenced by the number of elements. In both RT tasks, reaction times to the probe increased as a function of number of elements when the probe occurred during movement execution. The presence of the probe also caused an increase in aiming errors in the simple but not choice RT task. These findings indicated that online programming was occurring in both RT tasks. In the simple RT task, increased executive control mediated the integration between response elements through the utilization of visual feedback to facilitate the implementation of the second element.     

Stimulus intensity,catch trial effects,and the speed-accuracy tradeoff in reaction time: A variable criterion theory interptation

Ss responded to a 1,000-Hz tone of 50, 80, or 100 dB. Catch trial conditions were none, blank trials, a red light, a noise, and an 1,800-Hz tone. Auditory catch signals were of the same intensities. RT distributions in the first three conditions were well described by a family of exponential growth functions dependent upon stimulus intensity and by the parameters of normal criterion distributions dependent upon catch trial conditions and between-session variability. Performance in the auditory catch trial conditions was not dependent upon the same set of sensory growth functions. Performance in these conditions was described by a two-dimensional analysis of information transmitted as a function of time and interpreted in terms of variable criterion theory. The speed-accuracy tradeoff in this situation appears to depend upon differential rates of growth of intensity and associative information and the criterion used in responding to this information.     

Relationship between choice reaction time and the Tower of Hanoi test.

The aim of this study was to examine a possible relation between the speed of information processing, as measured by simple and choice visual RT, and problem-solving, as measured by the Tower of Hanoi test. For 20 normal teenagers, performing all tests, significant correlations were found between choice RT and both measures of performance on the Tower of Hanoi, number of disk moves, and time taken to complete the task. Simple RT was correlated with Completion time but not with the number of moves, while the reverse pattern was discerned for decision time. Choice movement time was also associated with both measures, but simple movement time was not. These results are consistent with the hypothesis of a common neurobiological basis to information-processing speed and executive functions.     

Probability effects in choice reaction time tasks

This paper contains a short review of the main results that were obtained by the author in a series of experiments that constituted a study of the effects of signal probability on choice reaction time. The effects of stimulus probability are shown to be influenced by the following variables: (1) differences in the method of varying stimulus probability, (2) differences in task complexity, (3) differences in S-R code, and (4) differences in Ss’ motivation. The data that are considered here are the overall mean RT for particular signals and the mean RT for sequential repetitions. Two questions, related to the psychological “nature” of the probability effects in choice RT are discussed: (1) The question of the relationship between the relative frequency and the number of alternatives as two different ways of determining the probability effect in choice RT; and (2) the question of identifying the main determinants of the trial-to-trial variability of RT in such experiments.