Additive factors analysis of inhibitory processing in the stop-signal paradigm

This article reports an additive factors analysis of choice reaction and selective stop processes manipulated in a stop-signal paradigm. Three experiments were performed in which stimulus discriminability (SD) and stimulus-response compatibility (SRC) were manipulated in a factorial fashion. In each experiment, the effects of SD and SRC were assessed first for going and next for stopping. Two experiments yielded the anticipated additive relation between SD and SRC for going but stopping appeared to be insensitive to the SD manipulation. Increasing the SD demands in the third experiment by using a different display resulted in a significant (over-additive) interaction between SD and SRC for going and a non-significant (under-additive) interaction for stopping. The pattern of results that emerged from this set of experiments was interpreted to suggest that going and stopping are both similar and different. They are similar in that distinct stages can be identified in both going and stopping but they are also different, as selective stopping seems to be less sensitive to discrimination manipulations relative to going.     

Horse-race model simulations of the stop-signal procedure

In the stop-signal paradigm, subjects perform a standard two-choice reaction task in which, occasionally and unpredictably, a stop-signal is presented requiring the inhibition of the response to the choice signal. The stop-signal paradigm has been successfully applied to assess the ability to inhibit under a wide range of experimental conditions and in various populations. The current study presents a set of evidence-based guidelines for using the stop-signal paradigm. The evidence was derived from a series of simulations aimed at (a) examining the effects of experimental design features on inhibition indices, and (b) testing the assumptions of the horse-race model that underlies the stop-signal paradigm. The simulations indicate that, under most conditions, the latency, but not variability, of response inhibition can be reliably estimated.     

The duration of response inhibition in the stop-signal paradigm varies with response force

In a previous study, we have found that the speed of stopping a response is delayed when response readiness is reduced by cuing the probability of no-go trials [Acta Psychol. 111 (2002) 155]. Other investigators observed that responses are more forceful when the probability to respond is low than when it is high (e.g. [Quart. J. Exp. Psychol. A 50 (1997) 405]). In this study, the hypothesis was tested that low probability responses are more forceful than high probability responses and that these responses are more difficult to stop. Subjects performed on a choice reaction task and on three tasks with respectively 100%, 80%, and 50% response probabilities. Stop signals were presented on 30% of the trials, instructing subjects to withhold their response. Response force on non-signal (go) trials and the duration of response inhibition on signal (stop) trials increased as response probability decreased. This pattern of findings was interpreted to support the hypothesis predicting that stopping is more difficult when response readiness is low than when it is high.     

Interidentity amnesia for neutral,episodic information in dissociative identity disorder

Interidentity amnesia is considered a hallmark of dissociative identity disorder (DID) in clinical practice. In this study, objective methods of testing episodic memory transfer between identities were used. Tests of both recall (interference paradigm) and recognition were used. A sample of 31 DID patients was included. Additionally, 50 control subjects participated, half functioning as normal controls and the other half simulating interidentity amnesia. Twenty-one patients subjectively reported complete one-way amnesia for the learning episode. However, objectively, neither recall nor recognition scores of patients were different from those of normal controls. It is suggested that clinical models of amnesia in DID may be specified to exclude episodic memory impairments for emotionally neutral material.     

What response times tell of children's behavior on the balance scale task

Analysis of accuracy of responses to balance scale problems gives a global idea of the cognitive processes that underlie problem-solving behavior on this task. We show that response times (RTs) provide additional detailed information about the kind and duration of these processes. We derive predictions about the RTs from Siegler's (1981) model for the balance scale task, including the counterintuitive prediction that young adults are slower than children in solving particular balance scale problems. The predictions were tested in a study in which 191 6- to 22-year-old participants were presented with a computerized balance scale task. RTs were analyzed with regression models. In addition to qualitative differences between items, we also modeled quantitative differences between items in the regression models. Analyses supported the predictions and provided additional knowledge on the rules. Rule II was reformulated as a rule that always involves the encoding, but not always the correct application of the distance cue. RTs provided evidence for the use of a buggy-rule and not an addition-rule. Finally, a relation between rule inconsistency and increased RT was found.     

Using response times to detect aberrant responses in computerized adaptive testing

A lognormal model for response times is used to check response times for aberrances in examinee behavior on computerized adaptive tests. Both classical procedures and Bayesian posterior predictive checks are presented. For a fixed examinee, responses and response times are independent; checks based on response times offer thus information independent of the results of checks on response patterns. Empirical examples of the use of classical and Bayesian checks for detecting two different types of aberrances in response times are presented. The detection rates for the Bayesian checks outperformed those for the classical checks, but at the cost of higher false-alarm rates. A guideline for the choice between the two types of checks is offered.This study received funding from the Law School Admission Council (LSAC). The opinions and conclusions contained in this paper are those of the authors and do not necessarily reflect the policy and position of LSAC. The authors are most indebted to Wim M. M. Tielen for his computational assistance and to the US Defense Manpower Data Center for the permission to use the ASVAB data set in the empirical examples.     

Effects of mixed versus blocked design on stimulus evaluation: combining underadditive effects

According to the asynchronous discrete coding model of Miller, two manipulations should display underadditive effects on reaction time if they slow down noncontingent stages associated with the processing of two separable dimensions of a stimulus. Underadditive effects are also predicted by a dual route model when a task variable is factorially varied with design type (mixed vs blocked). Interpretations of both underadditive effects and their combination were evaluated. Intact and degraded stimuli were presented to 18 young adults either in a single block (mixed) or in separate blocks (blocked). Spatial stimulus-response (S-R) compatibility was manipulated in all conditions. Stimulus degradation and S-R compatibility interacted underadditively, but only in blocked presentations. Both interpretations of underadditive effects were supported. Eye-movement registrations provided additional support for the alternative routes model.     

Empathy, an integrative model

Empathy research has yielded various separate insights into empathy and its correlates. Yet a comprehensive theoretical account that situates these factors within a larger framework is lacking. In this paper a conception of empathy is proposed and defended, which makes it possible to provide an encompassing reconstruction of the processes that are characteristic of empathic encounters. This conception situates empathy within a context of communication. Doing so allows one to connect various treads in empathy research, but at the same time urges one to take new factors into account. It is argued that empathy is a response to a specific demand occurring in a specific context. The type of answer persons are able to provide depends on four types of factors. First, there are the psychological empathic components. We argue that empathy should be seen as a combination of (especially) parallel and reactive emotions, against a background of specific cognitive abilities. Second, it is argued that empathy is aided by a twofold control system, comprised of judgements and forms of self-control. Third, personality factors play a part in how a person responds to demands. Finally, but most importantly, it is pointed out that specific relational factors codetermine empathic reactions. In this paper we describe the theoretical background of our model and provide an elaborated account of the four factors that determine empathic acts in a given context. We illustrate the viability of our model by presenting observational data of children's empathic acts.     

WAIS-III factor index score patterns after traumatic brain injury

Profile subtypes, based on the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) factor index scores, were examined in a sample of 166 patients with traumatic brain injury (TBI) by means of a two-stage clustering procedure. Three reliable subtypes were found that were differentiated primarily by level of performance across all factor index scores, although each of them demonstrated a relative weakness on the Processing Speed index. These subtypes were then validated on the basis of demographic variables, injury parameters, and additional psychometric measures that had not been included in the clustering procedures. The results indicated that performance on the WAIS-III after TBI was affected by both injury severity and level of education. It is concluded that there is no unique "signature" profile on the WAIS-III after TBI, except that a relative strength on the Processing Speed index is uncommon with this condition.