Response Errors Explain the Failure of Independent-Channels Models of Perception of Temporal Order

Independent-channels models of perception of temporal order (also referred to as threshold models or perceptual latency models) have been ruled out because two formal properties of these models (monotonicity and parallelism) are not borne out by data from ternary tasks in which observers must judge whether stimulus A was presented before, after, or simultaneously with stimulus B. These models generally assume that observed responses are authentic indicators of unobservable judgments, but blinks, lapses of attention, or errors in pressing the response keys (maybe, but not only, motivated by time pressure when reaction times are being recorded) may make observers misreport their judgments or simply guess a response. We present an extension of independent-channels models that considers response errors and we show that the model produces psychometric functions that do not satisfy monotonicity and parallelism. The model is illustrated by fitting it to data from a published study in which the ternary task was used. The fitted functions describe very accurately the absence of monotonicity and parallelism shown by the data. These characteristics of empirical data are thus consistent with independent-channels models when response errors are taken into consideration. The implications of these results for the analysis and interpretation of temporal order judgment data are discussed

Improving the Estimation of Psychometric Functions in 2AFC Discrimination Tasks

Ulrich and Vorberg (2009) presented a method that fits distinct functions for each order of presentation of standard and test stimuli in a two-alternative forced-choice (2AFC) discrimination task, which removes the contaminating influence of order effects from estimates of the difference limen. The two functions are fitted simultaneously under the constraint that their average evaluates to 0.5 when test and standard have the same magnitude, which was regarded as a general property of 2AFC tasks. This constraint implies that physical identity produces indistinguishability, which is valid when test and standard are identical except for magnitude along the dimension of comparison. However, indistinguishability does not occur at physical identity when test and standard differ on dimensions other than that along which they are compared (e.g., vertical and horizontal lines of the same length are not perceived to have the same length). In these cases, the method of Ulrich and Vorberg cannot be used. We propose a generalization of their method for use in such cases and illustrate it with data from a 2AFC experiment involving length discrimination of horizontal and vertical lines. The resultant data could be fitted with our generalization but not with the method of Ulrich and Vorberg. Further extensions of this method are discussed

Accuracy and precision of responses to visual analog scales: Inter- and intra-individual variability

Visual analog scales (VASs) are gaining popularity for collecting responses in computer administration of psychometric tests and surveys. The VAS format consists of a line marked at its endpoints with the minimum and maximum positions that it covers for respondents to place a mark at their selected location. Creating the line with intermediate marks along its length was discouraged, but no empirical evidence has ever been produced to show that their absence does any good. We report a study that asked respondents to place marks at pre-selected locations on a 100-unit VAS line, first when it only had numerical labels (0 and 100) at its endpoints and then when intermediate locations (from 0 to 100 in steps of 20) were also labeled. The results show that settings are more accurate and more precise when the VAS line has intermediate tick marks: The average absolute error decreased from 3.02 units without intermediate marks to 0.82 units with them. Provision of intermediate tick marks also reduced substantially inter- and intra-individual variability in accuracy and precision: The standard deviation of absolute error decreased from 0.87 units without tick marks to 0.25 units with them and the standard deviation of signed distance to target decreased from 1.16 units without tick marks to 0.24 units with them. These results prompt the recommendation that the design of VASs includes intermediate tick marks along the length of the line

Sistematización del seguimiento/acreditación de los títulos de doctorado: Un protocolo de buenas prácticas

El objetivo de este proyecto es diseñar una estrategia de monitorización del Programa de Doctorado en Psicología, junto con un protocolo de buenas prácticas para que cualquier titulación de la UCM pueda superar con éxito el proceso de acreditación.Fac. de PsicologíaFALSEVicerrectorado de Calidad, UCMsubmitte