Reaction times as a measure of uncertainty / El tiempo de reacción como una medida de incertidumbre

In this article, a method is presented to analyse relationships between detection or discrimination frequencies and reaction times in psychophysical tasks. It is shown in three empirical data sets that reaction time decreases as a linear function of the absolute value of the logit transforms of the response probabilities. Such a function stresses the characteristic uncertainty associated with subjects’ responses and the relation between their response parameters and the response criterion used by the subjects (AU)

En este artículo se presenta un método para analizar las relaciones entre las frecuencias de detección o discriminación y el tiempo de reacción en tareas psicofísicas. A partir de tres conjuntos de datos empíricos se demuestra que el tiempo de reacción disminuye según una función lineal del valor absoluto del logit de las probabilidades de respuesta. Esta función pone de relevancia la incertidumbre característica asociada a las respuestas de los sujetos y la relación entre sus parámetros y el criterio de respuesta empleado por éstos (AU)

Reaction times as a measure of uncertainty.

In this article, a method is presented to analyse relationships between detection or discrimination frequencies and reaction times in psychophysical tasks. It is shown in three empirical data sets that reaction time decreases as a linear function of the absolute value of the logit transforms of the response probabilities. Such a function stresses the characteristic uncertainty associated with subjects' responses and the relation between their response parameters and the response criterion used by the subjects.

Visual representations of dynamic actions from static pictures.

We investigated how subjects used their knowledge of biomechanical constraints when judging whether different items were in balance or in the process of falling, as a function of their angle of slant. In the first experiment, the stimuli were pictures of postures of a human body, of a wooden mannequin, and of a skeleton. The results show that for these 3 items, fall responses appeared for a smaller slant angle for a backward slant than for a forward one. This difference may reflect the influence of biomechanical constraints. To verify whether the asymmetry of the responses to the mannequin and the skeleton was genuine or due to some semantic context effect, a second experiment was run with only pictures of a wooden mannequin. The same asymmetry was observed. In a third experiment, falling judgments were obtained for pictures of a human body and of a structurally comparable artifactual object. The asymmetry of the fall responses appeared only for the human body.

Tiempo de reacción: del cronoscopio a la teoría de ondas / Reaction time: from chronoscope to wave theory

En este trabajo se presenta un procedimiento para el análisis de los datos de tiempo de reacción. El procedimiento se deriva del modelo funcional propuesto por Bonnet y cols (Bonnet y Link, 1998; Bonnet y Dresp, 2001) que a su vez fue desarrollado a partir de las ideas de la Teoría de Ondas para la diferencia y la similitud propuesta por Link (1992). El propósito de dicho procedimiento es separar los componentes sensoriales de los decisionales en una respuesta conductual. A partir de los datos obtenidos en un experimento en donde se midió el tiempo de reacción al inicio del movimiento, se muestra la utilidad del procedimiento y se discuten las implicancias teóricas y las posibles aplicaciones que se derivan de la capacidad de discriminar los componentes sensoriales de los decisionales en las respuestas de tiempo de reacción (AU)

In this work we present a procedure to analyse reaction time data. The procedure is derived from the functional model proposed by Bonnet and others (Bonnet and Link, 1998; Bonnet and Dresp, 2001) which in it’s turn was developed from ideas stemming from the Wave Theory of difference and similarity proposed by Link (1992). The aim of this procedure is to separate sensorial from decisional components in a behavioural response. Using data obtained from an experiment in which we measured reaction time to motion onset, we show the usefulness of the procedure and we discuss the theoretical implications and possible applications that can be derived from the ability to discriminate sensorial from decisional components in reaction time responses (AU)

Speed of response initiation in a time-to-contact discrimination task reflects the use of eta.

Avoiding collisions and making interceptions seem to require an organism to estimate the time that will elapse before an object will arrive to the point of observation (time-to-contact). The most outstanding account for precise timing has been the tau hypothesis. However, recent studies demonstrate that tau is not the only source of information in judging time-to-contact. By measuring reaction time in a time-to-contact discrimination task, we show that the eta function, which is a specific combination of optical size and rate of expansion, explains both accuracy and the observed RT pattern. The results conform to the hypothesis that the observers initiate the response when eta reaches a response threshold value.

On the delay in processing high spatial frequency visual information: reaction time and VEP latency study of the effect of local intensity of stimulation.

Saleh and Bonnet [Fechner Day 98, p. 344] have shown that, upon parafoveal stimulation and up to 6.5 c/deg, reaction time (RT) is a function of grating contrast multiplied by grating period. The present experiments extend these findings to foveal stimulation within a wider spatial-frequency (SF) range and to stimuli of different duration. Both RT and latency of visually evoked potentials (VEP) were measured. The findings might be explained by the following assumption: Most RT and VEP latency variations across the SF range are a result of local intensity factors (retinal contrast and width of grating bars). Residual RT variations were found that might be due to processing of high SFs by slower mechanisms than those processing low and medium SFs.