Two interpretations of the discrimination parameter

In this paper we propose two interpretations for the discrimination parameter in the two-parameter logistic model (2PLM). The interpretations are based on the relation between the 2PLM and two stochastic models. In the first interpretation, the 2PLM is linked to a diffusion model so that the probability of absorption equals the 2PLM. The discrimination parameter is the distance between the two absorbing boundaries and therefore the amount of information that has to be collected before a response to an item can be given. For the second interpretation, the 2PLM is connected to a specific type of race model. In the race model, the discrimination parameter is inversely related to the dependency of the information used in the decision process. Extended versions of both models with person-to-person variability in the difficulty parameter are considered. When fitted to a data set, it is shown that a generalization of the race model that allows for dependency between choices and response times (RTs) is the best-fitting model.     

The General Health Questionnaire and Eysenck's three-dimensional model of personality

A sample of 115 men and women between the ages of 20 and 60 completed the 30-item General Health Questionnaire together with the short-form Revised Eysenck Personality Questionnaire. The data indicate psychological distress so assessed is correlated .43 (p <.001) with Neuroticism and -.26 (p <.01) with Introversion but is unrelated to Psychoticism scores.     

Fragment memories mark the end of childhood amnesia

Adults described and dated two kinds of first remembrances: a personal event memory (the recollection of a personal episode that had occurred at some time in some place) and a memory fragment (an isolated memory moment having no event context and remembered, perhaps, as an image, a behavior, or an emotion). First fragment memories were judged to have originated substantially earlier in life than first event memories--approximately 3 1/3 years of age for first fragment memories versus roughly 4 years of age for first event memories. We conclude that the end of childhood amnesia is marked not by our earliest episodic memories, but by the earliest remembered fragments of childhood experiences.     

Decision-bound theory and the influence of familiarity

In this article, we derive a nonparametric prediction from decision-bound theory (DBT). The crucial aspect that is tested is whether or not familiarity of a stimulus affects response time in categorization. We show that, for our design, DBT, extended with some reasonable and testable assumptions, predicts no familiarity effect. Our prediction is nonparametric in that, rather than fit a specific instantiation of general DBT, we posit only some general assumptions of this theory and derive the prediction from these assumptions. It is found that familiarity did have a strong impact on response time for at least half of our participants. We suggest that DBT is in itself incomplete and should be extended to account for the full range of available data.     

Interactions of afterimages for orientation and color: experimental data and model simulations

Sequential viewing of two orthogonally related patterns produces an afterimage of the first pattern. We report an experiment that quantifies some properties of this type of afterimage. It is shown that it is important for the two patterns to have orthogonal orientations and that the appearance of the afterimage does not depend on the spatial frequency of the second pattern. We then show that Grossberg's model of interacting boundary and feature contour systems can account for the observed properties of these afterimages.     

On the (non)categorical perception of lexical tones

Identification and discrimination of lexical tones in Cantonese were compared in the context of a traditional categorical perception paradigm. Three lexical tone continua were used: one ranging from low level to high level, one from high rising to high level, and one from low falling to high rising. Identification data showed steep slopes at category boundaries, suggesting that lexical tones are perceived categorically. In contrast, discrimination curves generally showed much weaker evidence for categorical perception. Subsequent investigation showed that the presence of a tonal context played a strong role in the identification of target tones and less of a role in discrimination. The results are consistent with the hypothesis that tonal category boundaries are determined by a combination of regions of natural auditory sensitivity and the influence of linguistic experience.     

Inhibition of return for the length of a line?

Inhibition of return is most often measured using an exogenous spatial cuing method. The experiments presented here follow up on a small number of studies that have examined whether a similar effect occurs for nonspatial stimulus attributes. In Experiments 1 and 2, the task was to identify a target line as either short or long. In this context, targets on valid trials were of the same length as that of a preceding cue, whereas targets on invalid trials were of a different length than that of a preceding cue. The results were similar to those in spatial orienting studies in that responses were slower for valid than for invalid targets only at stimulus onset asynchronies (SOAs) longer than 300 msec. In Experiment 3, the stimuli were the same but the task was to detect the onset of the target line. This task change resulted in slower responses for valid than for invalid targets at all SOAs. A similar result was observed in Experiment 4, in which validity was defined by color rather than line length, and the task was to identify the target color. The discussion centers on an opponent process approach to interpreting cuing effects, and consequent difficulties in distinguishing spatial and nonspatial cuing effects based on their time course.     

A nonlinear mixed model framework for item response theory

Mixed models take the dependency between observations based on the same cluster into account by introducing 1 or more random effects. Common item response theory (IRT) models introduce latent person variables to model the dependence between responses of the same participant. Assuming a distribution for the latent variables, these IRT models are formally equivalent with nonlinear mixed models. It is shown how a variety of IRT models can be formulated as particular instances of nonlinear mixed models. The unifying framework offers the advantage that relations between different IRT models become explicit and that it is rather straightforward to see how existing IRT models can be adapted and extended. The approach is illustrated with a self-report study on anger.     

Psychological type and attitude toward Christianity: a replication

A sample of 149 university students completed the Francis Psychological Type Scales together with the Francis Scale of Attitude Toward Christianity. The data indicated that university students classified as Feeling Types hold a more positive attitude toward Christianity than those classified as Thinking Types. These findings replicate the 1999 report of Jones and Francis.