On measuring the minimum detection time: A simple reaction time study in the time estimation paradigm

Kornblum's time estimation paradigm, together with the so‐called ‘race model’, provides an appealing alternative for measuring the ‘cut‐off’ which separates ‘true’ reaction times from anticipatory reaction times. However, the model is not precise enough to reveal the relation between the signal intensity and the ‘cut‐off’. Accordingly, Kornblum's model is extended with an emphasis on the measure of the ‘cut‐off’. Another aspect of the extension is to use a parametric method to analyse the data. In particular, it is assumed that the time estimation‐induced latency is gamma distributed and the signal‐induced latency is Weibull distributed, with the latter shifted by the ‘cut‐off’. The rationale behind the parametric assumption is discussed. For illustrative purposes, two pieces of experimental work are presented. Since the core of the race model is the assumption of an independent race between the time estimation process and the detection process, the first experiment tests whether, for the same signal intensity, the signal‐induced latency distribution is invariant across different time intervals; the second experiment tests whether, for the same time interval, the time estimation‐induced latency distribution is invariant across different signal intensity conditions. The data from the second experiment are also used to test various parametric assumptions in the model, which include the signal effect on the ‘cut‐off’. The new model fits the data well.     

List length and the time course of recognition in immediate memory

The response signal method of Reed (1973) was used to study the time-course of list membership recognition after 2 sec of uncontrolled rehearsal, with lists of one, two, and four consonants. Fourteen specific hypotheses about the time course of this process were derived from various theories (Anderson, 1973; Anderson & Bower, 1973; Baddeley & Ecob, 1973; Corballis, Kirby, & Miller, 1972; Kirsner, 1972; Murdock, 1971; Sternberg, 1966, 1969; Theios, Smith, Haviland, Traupmann, & Moy, 1973; etc.) and additional assumptions about the effect of the response signal. When members of the to-be-learned lists are drawn from a small population of highly confusable items, as in the current experiment, list membership recognition appears to follow the model of Theios et al. (1973). Latency functions of signal lag appear to be particularly useful in differentiating among hypotheses which predict similar speed-accuracy tradeoff functions. The lag by positive-negative interaction for latencies of correct responses is highly significant for lists of one consonant, a result predicted by the hypothesis derived from the model of Theios et al. and incompatible with hypotheses derived from exhaustive search and single-threshold strength models.     

Speed-accuracy tradeoff models for auditory detection with deadlines

Two neural models for response latency in auditory signal detection are considered: the Timing model of Luce and Green (1972) and a modified counting model based on that of McGill (1967). The modified counting model is described in some detail. The experimental situation to which the models are applied is one where a deadline in response time is enforced on signal trials only or on noise trials only, the condition of deadlines on both cases having previously been studied by Green and Luce (1973). The results for mean latencies of the various categories of response, together with response probabilities, favour either the counting model or a dual process model. Data for ROC curves indicate either the operation of a dual process model or that the ‘interval of uncertainty’ of the counting model may vary with bias position. Some consideration is also given to the possibility of differential residual response time components and it is concluded that such components may be important in the deadline situation.     

Comparison of yes-no and latency measures of auditory intensity discrimination.

Rats discriminated auditory intensity differences of sinusoids at 3.0 kilohertz in a go/no-go signal detection procedure. Responses to the signal (hits) were reinforced with electrical brain stimulation, and misses produced a brief timeout. On intermixed noise trials, withholding of responses (correct rejections) was reinforced, and false alarms produced the time-out. In two test conditions, the signal was either the louder (100 decibels) or softer (90, 93, 96, or 99 decibels) of the pair of intensities presented within a set of trials. Each animal was first trained with signal value louder or softer, and reversed for the second condition so that the former noise value served as signal. Hits showed shorter latencies than false alarms, regardless of the relative intensity of signal and noise, and the magnitude of differentiation was proportional to signal-noise separation. Both hits and false alarms showed longer latencies as the discrimination became more difficult. Isosensitivity contours derived from the latencies showed close similarity across conditions; in comparison, the yes-no measure of detectability, d', showed greater variability. The similarity of latency differentiation across louder and softer signal conditions supports a detection model in which the observer's judgment is controlled by the distance of sensory effect from criterion on each trial, as opposed to the loudness of the tones per se.     

Effects of rate of signal rise and decay on reaction time to the onset and offset of acoustic stimuli

This study assessed the effects of variations in signal rise-decay time on response latencies to the onset and cessation of a 1,000-Hz tone. Onset and offset reactions were combined factorially with five rates of signal rise-decay (0.5, 5, 25, 100, and 250 msec) to produce a total of 10 experimental conditions. Offset RTs were significantly longer than onset RTs when the rise-decay time of the tone was 250 msec. Disparities in speed of reaction to tone onset and cessation were negligible at the remaining rates of signal rise-decay.     

Attentional localization prior to simple and directed manual responses

The relationship between attention and the programming of motor responses was investigated, using a paradigm in which the onsets of targets for movements were preceded by peripheral attentional cues. Simple (button release) and reaching manual responses were compared under conditions in which the subjects either made saccades toward the target location or refrained from making eye movements. The timing of the movement onset was used as the dependent measure for both simple and reaching manual responses. Eye movement latencies were also measured. A follow-up experiment measured the effect of the same peripheral cuing procedure on purely visual processes, using signal detection measures of visual sensitivity and response bias. The results of the first experiment showed that reaction time (RT) increased with the distance between the cued and the target locations. Stronger distance effects were observed when goal-directed responses were required, which suggests enhanced attentional localization of target positions under these conditions. The requirement to generate an eye movement response was found to delay simple manual RTs. However, mean reaching RTs were unaffected by the eye movement condition. Distance gradients on eye movement latencies were relatively shallow, as compared with those on goal-directed manual responses. The second experiment showed that the peripheral cue had only a very small effect on visual detection sensitivity in the absence of directed motor responses. It is concluded that cue-target distance effects with peripheral cues are modulated by the motor-programming requirements of the task. The effect of the peripheral cue on eye movement latencies was qualitatively different from that observed on manual RTs, indicating the existence of separate neural representations underlying both response types. At the same time, the interactions between response modalities are consistent with a supramodal representation of attentional space, within which different motor programs may interact.     

Behavioral definition of minimal reaction time in monkeys

Two monkeys (Macaca mulatta) were trained to press a key after onset of a tone and to release it after a 1-sec fixed foreperiod terminated by a light. The effects of imposing temporal contingencies on key release reaction times were determined by reinforcing only those releases whose latencies from the light fell within a “payoff band”, two time limits 50 msec apart located at some delay following the light. Over several days this delay was first gradually decreased, shortening the interval between light and payoff band, and then gradually increased again. For each delay, the median reaction time and a measure of variability were obtained from the latency distribution. For both animals, median latency could be decreased to 180 msec with the variability remaining small. Moving the payoff band still closer to the light resulted in further decrease in median latency but an abrupt increase in variability. This is in agreement with a model for simple reaction time derived from human research which suggests that this increased variability results from the inclusion of high-variability foreperiod time estimations in the latency distribution. These results indicate that interpretation of monkey response latencies as “minimal reaction times” requires examination of temporal reinforcement contingencies and variability of latencies.     

Connectionist and diffusion models of reaction time.

Two connectionist frameworks, GRAIN (J. L. McClelland, 1993) and brain-state-in-a-box (J. A. Anderson, 1991), and R. Ratcliff's (1978) diffusion model were evaluated using data from a signal detection task. Dependent variables included response probabilities, reaction times for correct and error responses, and shapes of reaction-time distributions. The diffusion model accounted for all aspects of the data, including error reaction times that had previously been a problem for all response-time models. The connectionist models accounted for many aspects of the data adequately, but each failed to a greater or lesser degree in important ways except for one model that was similar to the diffusion model. The findings advance the development of the diffusion model and show that the long tradition of reaction-time research and theory is a fertile domain for development and testing of connectionist assumptions about how decisions are generated over time.     

Controlled attention sharing influences time estimation

A seminal attentional model of time estimation predicts that subjective duration will be positively correlated to the amount of attention given to temporal processing. This prediction holds under prospective conditions, in which one is forewarned that judgments of time will be asked, in contrast to retrospective conditions, in which such judgments are required after the relevant period without any prior warning. In three experiments, an attention-sharing method was used. Subjects were asked to control the amount of attention that they devoted to one or the other component of a dual-task paradigm. The first experiment involved word categorization and reproduction of duration. The following experiments, based on signal detection theory, required discrimination of both the duration and the intensity of a single stimulus, in the visual (Experiment 2) or the auditory (Experiment 3) modality. The results indicate that when the attention is directly controlled by the subject, the subjective duration shortens as the amount of attention devoted to the temporal task diminishes. The implications of these results for the possible existence of an internal timer are considered.     

Attentional localization prior to simpleand directed manual responses

The relationship between attention and the programming of motor responses was investigated, using a paradigm in which the onsets of targets for movements were preceded by peripheral attentional cues. Simple (button release) and reaching manual responses were compared under conditions in which the subjects either made saccades toward the target location or refrained from making eye movements. The timing of the movement onset was used as the dependent measure for both simple and reaching manual responses. Eye movement latencies were also measured. A follow-up experiment measured the effect of the same peripheral cuing procedure on purely visual processes, using signal detection mea-sures of visual sensitivity and response bias. The results of the first experiment showed that reaction time (RT) increased with the distance between the cued and the target locations. Stronger distance ef-fects were observed when goal-directed responses were required, which suggests enhanced attentional localization of target positions under these conditions. The requirement to generate an eye movement response was found to delay simple manual RTs. However, mean reaching RTs were unaffected by the eye movement condition. Distance gradients on eye movement latencies were relatively shallow, as compared with those on goal-directed manual responses. The second experiment showed that the peripheral cue had only a very small effect on visual detection sensitivity in the absence of directed motor responses. It is concluded that cue-target distance effects with peripheral cues are modulated by the motor-programming requirements of the task. The effect of the peripheral cue on eye movement latencies was qualitatively different from that observed on manual RTs, indicating the existence of separate neural representations underlying both response types. At the same time, the interactions be-tween response modalities are consistent with a supramodal representation of attentional space, within which different motor programs may interact.     

Exploring the time course of semantic interference and associative priming in the picture-word interference task

The picture-word interference (PWI) task is a widely used technique for exploring effects of semantic context on lexical access. In this task, printed words are superimposed over pictures to be named, with the timing of the interfering word relative to the picture systematically manipulated. Two experiments (N = 24 adults in each) explored the time course of effects of associates (e.g., CARROT superimposed on a picture of a rabbit) versus coordinates (e.g., CHIPMUNK superimposed on a picture of a rabbit) on naming latencies. Associates led to faster picture naming than did unrelated words, with facilitative effects occurring at stimulus onset asynchronies (SOAs, in ms) ranging from -450 to 0. Coordinates led to slower naming latencies, with the interference effect restricted to SOAs of -150 and 0. The overlapping time course of associative priming and coordinate interference provides important constraints on models of lexical access in speech production.     

The Ornstein-Uhlenbeck model for decision time in cognitive tasks: An example of control of nonlinear network dynamics

The Ornstein-Uhlenbeck (OU) model for human decision-making has been successfully applied to account for response accuracy and response time (RT) data in recent two-choice decision models. A variant of the OU model is shown to arise from the response dynamics of a nonlinear network consisting of randomly connected neural processing units. When feedback control of the network is effected by the stimulus onset, the average network response is an autocorrelated random signal satisfying the stochastic differential equation for the OU process. An alternative, more general, stimulus detection procedure is proposed which involves the use of an adaptive Kalman filter process to track any temporal change in autoregressive parameters. The predicted decision time distributions suggest that both the OU and the Kalman filter processes can serve as alternative models for RT data in experimental tasks. Received: 15 October 1998 / Accepted: 27 May 1999     

Response latencies in the yes/no detection task: An assessment of two basic models

Two general forms of model for response latency in the yes no signal detection task are described and their predictions examined in the light of experimental data. One model supposes a latency function along the detection axis and the other supposes that a count is made of multiple observation, Experiment I looks at the auditory detection situation with short observation interval, but the results are generally equixocal, although the latency function model gives a simpler interpretation Other results are then discussed, particularly those of Gescheider et al (1969). and it is concluded that an attempt must be made to replicate the results of Carterette et al (1965) for the extended observation interval detection experiment. This is achieved in Experiment II. and the obtained order of mean latencies is then examined in terms of the models The counting model appears by far the more suitable for this situation.     

Decreases in simple reaction time as a function of stutterers'' participation in a behavioral therapy

Stutterers and fluent speakers were compared on a simple reastion time task to determine whether participation in a behaviorally based stuttering program had an effect on clients' reaction time scores. A group of fluent speakers was used to control the possibility that any changes in reaction time latency were due to practice or familiarity with the task. All participants responded with a finger-lift as quickly as possible to 25 visual stimuli presented by computer. Response latencies from the stutterers and the fluent speakers were compared. Stutterers' posttherapy reaction time latencies were significantly shorter than their pretherapy latencies. It was also observed that stutterers' reaction time scores prior to therapy did not differ significantly from fluent speakers' scores. However, stutterers' posttherapy reaction time scores did differ significantly from fluent speakers' posttest scores. The results are discussed in terms of arousal, motivation, familiarity with the environment, conditioned inhibition, and two aspects of therapy.     

Effects of race on responses and response latencies in the weapon identification task: a test of six models

The authors consider six models of underlying process in the weapon identification task: The first two are response-time extensions of signal detection models; the last four, of the process dissociation model. Predictions for accuracy data, correct response latencies, and false response latencies are used to discriminate between models. In the present study, racial bias in responses and correct response latency was replicated. New findings were that the direction of bias was reversed in error latency and that errors were faster than correct responses. These findings rule out four models, in particular, the idea that race biases early perception and interpretation of targets. Implications for reducing errors in the weapon identification task and possibilities of discriminating between the remaining two models are discussed.     

Smoothing enhances the detection of common structure from multiple time series

The effects of smoothing (i.e., temporal averaging) on the detection of intraindividual interdependency from between-subjects aggregated (i.e., multiple) bivariate time series were examined. A simple moving average smoother was applied to different types of simulated processes that included error. The results indicated that smoothing facilitates the detection of common intraindividual structure from multiple time series. The efficacy of smoothing was dependent on the characteristics of the underlying process. It is suggested that smoothing increases the efficiency of the detection of common structure by increasing the signal-to-noise ratio (i.e., temporal reliability) of the time series. The issue and application of smoothing is further discussed in terms of signal extraction and classical test theory.     

Separating the effects of interreinforcement time and number of interreinforcement responses

The relative importance of interreinforcement time and interreinforcement responses was evaluated by varying each independently. To do this, a blackout was presented after each nonreinforced response under both fixed-ratio and fixed-interval schedules of reinforcement. Manipulating the blackout duration under the fixed-ratio schedule caused interreinforcement time to vary without affecting the number of interreinforcement responses. Pigeons' post-reinforcement and post-blackout response latencies were found to increase linearly with interreinforcement time. Under the fixed-interval schedule, the same blackout manipulations changed the number of interreinforcement responses without affecting interreinforcement time. Post-reinforcement and post-blackout response latencies under this condition were approximately constant. These results suggest that responding is controlled by interreinforcement time and is not influenced by the number of responses emitted between reinforcements.     

A discrete time model for detection of randomly presented stimuli

Considered in this paper is a discrete-time Markov decision process with unobservable states, which occurs in equipment checking, medical diagnosis, signal detection, and reaction time studies. The process is characterized by (i) a state S₀ that at some unknown time t, which is determined probabilistically, turns into an absorbing state S₁; (ii) observations that provide fallible information about the true state and which are taken sequentially to determine whether or not the change from S₀ to S₁ has occurred; and (iii) losses for a false alarm and for delays in detecting the change. A response model is proposed, prescribing a terminal decision as soon as the posterior probability that S₁ obtains reaches or exceeds a fixed probability boundary. Predictions are derived concerning the probability of false alarm and several conditional distributions of the number of observations taken.     

The visual-auditory color-word Stroop asymmetry and its time course

Four experiments examined crossmodal versions of the Stroop task in order (1) to look for Stroop asymmetries in color naming, spoken-word naming, and written-word naming and to evaluate the time course of these asymmetries, and (2) to compare these findings to current models of the Stroop effect. Participants named color patches while ignoring spoken color words presented with an onset varying from 300 msec before to 300 msec after the onset of the color (Experiment 1), or they named the spoken words and ignored the colors (Experiment 2). A secondary visual detection task assured that the participants looked at the colors in both tasks. Spoken color words yielded Stroop effects in color naming, but colors did not yield an effect in spoken-word naming at any stimulus onset asynchrony. This asymmetry in effects was obtained with equivalent color- and spoken-word-naming latencies. Written color words yielded a Stroop effect in naming spoken words (Experiment 3), and spoken color words yielded an effect in naming written words (Experiment 4). These results were interpreted as most consistent with an architectural account of the color-word Stroop asymmetry, in contrast with discriminability and pathway strength accounts.     

Inspection time and the mental age deviation hypothesis

The ‘g’-loading of the inspection time (IT) measure was tested by applying Spitz's mental age (MA) deviation model to a sample of non-retarded adolescents and children. An MA 8 and MA 11 group, each composed of below-average, average and above-average intelligence Ss, were compared on an IT task in which latency of responses was also recorded. Results showed that IT related to MA but not to IQ. By contrast, the latency of responding in the IT differentiated Ss by IQ, but not MA, with above-average IQ Ss exhibiting longer response latencies. It was concluded that response latency exhibited a higher ‘g’-loading than did IT.