Threshold estimation in two-alternative forced-choice (2AFC) tasks: The Spearman-Kärber method

The Spearman-Kärber method can be used to estimate the threshold value or difference limen in two-alternative forced-choice tasks. This method yields a simple estimator for the difference limen and its standard error, so that both can be calculated with a pocket calculator. In contrast to previous estimators, the present approach does not require any assumptions about the shape of the true underlying psychometric function. The performance of this new nonparametric estimator is compared with the standard technique of probit analysis. The Spearman-Kärber method appears to be a valuable addition to the toolbox of psychophysical methods, because it is most accurate for estimating the mean (i.e., absolute and difference thresholds) and dispersion of the psychometric function, although it is not optimal for estimating percentile-based parameters of this function.     

Structural Validation of the Hamilton Depression Rating Scale

Despite the prolific use of the Hamilton Depression Rating Scale (HDRS), there have been no prior studies using confirmatory factor analysis (CFA) to compare competing HDRS latent structures. The current study undertakes this task, examining CFAs on 397 older adults on the most stable latent models previously posited and a new rationally derived model by Cole and Motivala. CFAs were evaluated in their original first-order structure and in hierarchically related counterparts. All hierarchical models performed significantly better than their first-order counterparts. Moreover, the hierarchical Cole and Motivala model was significantly better on all comparative criteria than any of the other models. However, none of the tested models obtained sufficient fit with the data suggesting psychometric, scoring, or content limitations of the scale.     

Threatening pictures induce shortened time-to-contact estimates

The ability to estimate the time remaining until collision occurs with an approaching object (time-to-collision, TTC) is crucial for any mobile animal. In the present study, we report three experiments examining whether higher level cognitive factors, represented by affective value of approaching objects, could affect judgments of TTC. A theory of TTC estimates based purely on the optical variable tau does not predict an influence of the affective value of an approaching object. In Experiments 1 and 2, we compared TTC estimates of threatening and neutral pictures that approached our participants on a screen and disappeared from view before a collision would have occurred. Images were taken from the International Affective Picture System. Threatening pictures??in particular, the picture of a frontal attack??were judged to collide earlier than neutral pictures. In Experiment 3, the approaching stimuli were faces with different emotional expressions. TTC tended to be underestimated for angry faces. We discuss these results, considering the roles of affective and cognitive mechanisms modulating TTC estimation and general time perception.     

Nonselective motor-level changes associated with selective response inhibition: evidence from response force measurements

In the present study, we examined the effects of selective response inhibition on motor production using response force measures within a task that was based on that of Aron and Verbruggen (Psychological Science, 19, 1146–1153, 2008). In each trial, participants were signaled to respond bimanually with the two index fingers or the two middle fingers. After a short delay, a stop signal was sometimes presented, indicating that one of the two finger responses should be withheld. A given response was slowed when the response on the other hand was stopped, replicating a previously observed stopping interference effect. In addition, the given response was also made more forcefully when the response on the other hand was stopped, indicating that the requirement to stop one activated response has global motor-level consequences for other responses that are to be carried out normally.     

Levels of modality for BDI Logic

The use of rational agents for modelling real world problems has both been heavily investigated and become well accepted, with BDI (Beliefs, Desires, and Intentions) Logic being a widely used architecture to represent and reason about rational agency. However, in the real world, we often have to deal with different levels of confidence in the beliefs we hold, desires we have, and intentions that we commit to. This paper extends our previous framework that integrated qualitative levels of beliefs, desires, and intentions into BDI Logic. We describe an expanded set of axioms and properties of the extended logic. We present a modular structure for the semantics which involves a non-normal Kripke type semantics that may be used for other agent systems. Further, we demonstrate the usefulness of our framework with a scheduling task example.     

Toward an understanding of situational judgment item validity and group differences

This paper evaluates 2 adjustments to common scoring approaches for situational judgment tests (SJTs). These adjustments can result in substantial improvements to item validity, reductions in mean racial differences, and resistance to coaching designed to improve scores. The first adjustment, applicable to SJTs that use Likert scales, controls for elevation and scatter (Cronbach & Gleser, 1953). This adjustment improves item validity. Also, because there is a White-Black mean difference in the preference for extreme responses on Likert scales (Bachman & O'Malley, 1984), these adjustments substantially reduce White-Black mean score differences. Furthermore, this adjustment often eliminates the score elevation associated with the coaching strategy of avoiding extreme responses (Cullen, Sackett, & Lievens, 2006). Item validity is shown to have a U-shaped relationship with item means. This holds both for SJTs with Likert score response formats and for SJTs where respondents identify the best and worst response option. Given the U-shaped relationship, the second adjustment is to drop items with midrange item means. This permits the SJT to be shortened, sometimes dramatically, without necessarily harming validity.     

Effects of motivating operations on problem and academic behavior in classrooms

The current study examined the effects of motivating operations on problem behavior and academic engagement for 2 students with autism. Classroom sessions were preceded by periods in which the participants had access or no access to the items functionally related to their problem behavior. Results suggested that presession access may result in lower levels of problem behavior and higher levels of academic engagement during classroom instruction.