Simple matrix methods for analyzing diffusion models of choice probability, choice response time, and simple response time

Diffusion processes (e.g., Wiener process, Ornstein-Uhlenbeck process) are powerful approaches to model human information processes in a variety of psychological tasks. Lack of mathematical tractability, however, has prevented broad applications of these models to empirical data. This tutorial explains step by step, using a matrix approach, how to construct these models, how to implement them on a computer, and how to calculate the predictions made by these models. In particular, we present models for binaries choices for unidimensional and multiattribute choice alternatives; for simple reaction time tasks; and for three alternatives choice problems.     

Perceived characteristics of “competent” people

The purpose of this research was to determine the specific behaviors and cues which 104 assessors perceived as indicating the presence of psychological variables shown to be related to competent job behavior. The cue systems utilized were found to be reminiscent of theory Y conceptions of effective job behavior. Implications of the lack of correlation of cue utilization with assessor characteristics are discussed.     

Writing the (researcher) self: reflective practice and undergraduate research

This paper discusses the way in which postmodern emergence was used to assist a group of undergraduate students come to new understandings of research practice as they participated in a reflective component of an Undergraduate Research Summer School. Students were encouraged to ‘write the (researcher) self’ through a collaborative writing group based on the theoretical and pedagogical work of Somerville. Postmodern emergence highlights three stages of learning; firstly, assigning time for wondering, then a liminal space for becoming and finally an opportunity for generating new knowledge. This article is both the tangible product of this emergence reflective writing process and a recommendation about the capacity of undergraduate students to engage with their own professionalisation and meaning-making.     

Prudentia as becoming-shame: knowledge production in Southern Theory research Practice

Over the last decade authors have critiqued the hegemonic structures that perpetuate knowledge hierarchies in the dominant research regimes that foster privilege across the globe. The authors in this article use collective biography to reflectively engage with knowledge production in the academy. They explore the nature of prudentia as an affective shame that surfaces through reflexive engagement with the politics of research cultures. Collective biography, as a ‘grassroots’ form of deliberate and collaborative interrogation, produces insight from ‘difficult knowledge’ that sheds light on power imbalance in North/South relations in research practice. In endeavouring to grapple with Southern Theory, the authors surface ‘unwelcome truths’. These disquieting ruptures reveal the power of prudentia for academics who are desirous to unsettle the complacency of Northern assumptions as they engage in an ongoing struggle with doing Southern Theory.     

A further test of sequential-sampling models that account for payoff effects on response bias in perceptual decision tasks

Recently, Diederich and Busemeyer (2006) evaluated three hypotheses formulated as particular versions of a sequential-sampling model to account for the effects of payoffs in a perceptual decision task with time constraints. The bound-change hypothesis states that payoffs affect the distance of the starting position of the decision process to each decision bound. The drift-rate-change hypothesis states that payoffs affect the drift rate of the decision process. The two-stage-processing hypothesis assumes two processes, one for processing payoffs and another for processing stimulus information, and that on a given trial, attention switches from one process to the other. The latter hypothesis gave the best account of their data. The present study investigated two questions: (1) Does the experimental setting influence decisions, and consequently affect the fits of the hypotheses? A task was conducted in two experimental settings--either the time limit or the payoff matrix was held constant within a given block of trials, using three different payoff matrices and four different time limits--in order to answer this question. (2) Could it be that participants neglect payoffs on some trials and stimulus information on others? To investigate this idea, a further hypothesis was considered, the mixture-of-processes hypothesis. Like the two-stage-processing hypothesis, it postulates two processes, one for payoffs and another for stimulus information. However, it differs from the previous hypothesis in assuming that on a given trial exactly one of the processes operates, never both. The present design had no effect on choice probability but may have affected choice response times (RTs). Overall, the two-stage-processing hypothesis gave the best account, with respect both to choice probabilities and to observed mean RTs and mean RT patterns within a choice pair.     

Clarification of the dual task dilemma: Lateralized effects for perfunctory and purposeful tasks in left- and right-handed males

The hypothesis that behavioral asymmetries with the dual task paradigm represent manual dominance was investigated with right- and left-handed males performing verbal and spatial tasks ordered by complexity. Lateralization was assessed for nonideational (perfunctory) and ideational (purposeful) components of tasks with multivariate and ANCOVA procedures. The outcomes of prerequisite tests showed the assumptions for conducting ANCOVA procedures were not satisfied with different handedness groups in the same design. However, results of the multivariate analyses suggest lateralized effects are more likely to represent the cognitive task when interference is high and may represent manual dominance when interference is low.     

Relationships between academic intrinsic motivation and anxiety in children and young adolescents

To test the hypothesis that academic intrinsic motivation and anxiety are negatively related when both are differentiated into academic subject areas, two self-report inventories measuring academic intrinsic motivation and anxiety were administered to fourth and seventh graders. Each inventory was differentiated into the subject areas of reading, math, social studies, and science to determine whether the relationship between academic intrinsic motivation and anxiety would vary according to subject area. The results supported the hypothesis and showed that the relationship is differentiated according to subject area. Fourth and seventh graders differed in the pattern of relationships. For seventh graders, negative correlations between academic intrinsic motivation and anxiety occurred only within corresponding subject areas, while for fourth graders the negative correlations occurred both within corresponding and between noncorresponding subject areas. Implications for assessment and school intervention are advanced.     

Main and interaction effects of metallic toxins on classroom behavior

This study investigated the relationships of metal levels and metal combinations to children's classroom behavior. Hair-metal concentrations of lead, arsenic, mercury, cadmium, and aluminum were determined in 80 randomly selected elementary-age children, who were also rated by their classroom teacher on the Walker Problem Behavior Identification Checklist (WPBIC). Parents were interviewed to control for confounding variables that may have affected behavioral development. Regression analysis indicated that the set of metals was significantly related to increased scores on four of the five WPBIC subscales and on the total scale, with lead being a major contributor to four of the six dependent measures. Metal combinations were significantly related to increased scores on the WPBIC subscales measuring acting-out, disturbed peer relations, and immaturity, and on the total scale. A continuing reexamination of metal poisoning concentrations is needed because metal levels and metal combinations previously thought harmless may be associated with nonadaptive classroom behavior.