Effects of redundant visual stimuli on temporal order judgments

Four experiments were conducted in order to compare the effects of stimulus redundancy on temporal order judgments (TOJs) and reaction times (RTs). In Experiments 1 and 2, participants were presented in each trial with a tone and either a single visual stimulus or two redundant visual stimuli. They were asked to judge whether the tone or the visual display was presented first. Judgments of the relative onset times of the visual and the auditory stimuli were virtually unaffected by the presentation of redundant, rather than single, visual stimuli. Experiments 3 and 4 used simple RT tasks with the same stimuli, and responses were much faster to redundant than to single visual stimuli. It appears that the traditional speedup of RT associated with redundant visual stimuli arises after the stimulus detection processes to which TOJs are sensitive.     

Updating situation models

The authors examined how situation models are updated during text comprehension. If comprehenders keep track of the evolving situation, they should update their models such that the most current information, the here and now, is more available than outdated information. Contrary to this updating hypothesis, E. J. O'Brien, M. L. Rizzella, J. E. Albrecht, and J. G. Halleran (1998) obtained results suggesting that outdated or incorrect information may still influence the comprehension process. The authors of the current study demonstrate that the nature of E. J. O'Brien et al.'s materials were the likely cause of this pattern of results. Hence, the current authors constructed materials that circumvent identified confounds and in a reading-time experiment obtained evidence supporting the here-and-now hypothesis.     

A computer program for Spearman-Kärber and probit analysis of psychometric function data

PMETRIC is a computer program for the analysis of observed psychometric functions. It can estimate the parameters of these functions, using either probit analysis (a parametric technique) or the Spearman-Kärber method (a nonparametric one). For probit analysis, either a maximum likelihood or a minimum χ² criterion may be used for parameter estimation. In addition, standard errors of parameter estimates can be estimated via bootstrapping. The program can be used to analyze data obtained from either yes-no orm-alternative forced-choice tasks. To facilitate the use of PMETRIC in simulation work, an associated program, PMETGEN, is provided for the generation of simulated psychometric function data. Use of PMETRIC is illustrated with data from a duration discrimination task.     

Perceptions of Ethical Behaviour among Business Faculty in Canada

Faculty members at Canadian business schools were surveyed regarding their ethical perceptions of behaviours related to undergraduate instruction. Fifty-five behavioural statements were listed and respondents were asked to rate the extent to which they felt each behaviour was ethical or unethical. The only item that respondents endorsed as unequivocally unethical (90% indicated it was definitely unethical) was Becoming sexually involved with an undergraduate in one of your classes. We also compared the results of our sample to those of an American sample. Overall, an interesting pattern of differences emerged between the responses obtained in Canada and the U.S. In general, the direction of the significant differences was such that Canadian professors viewed the behaviours in question as less ethical than did their American counterparts.     

Hemispheric differences in semantic-relatedness judgments

Subjects judged the semantic relatedness of word pairs presented to the left or right visual field. The word pairs were presented one below the other. On critical trials, the words' referents had a typical spatial relation, with one referent oriented above the other (e.g. ATTIC/BASEMENT). The spatial relation of the words either matched or mismatched the spatial relation of their referents. When presented to the left hemisphere, the match or mismatch did not have an effect. However, there was a reliable mismatch effect for pairs presented to the right hemisphere. The results are interpreted in the context of perceptual theories of mental representation.     

Untangling developmental relations between depressed mood and delinquency in male adolescents

Relations between depressed mood and delinquency were investigated in a longitudinal sample of 506 urban adolescent males across ages 13.5–17.5, while adjusting for common risk factors. Adolescents provided yearly reports of their delinquent activities and depressed mood, as well as reports of peer delinquency at age 13.5 (i.e., baseline). Primary caregivers and teachers provided reports of risk factors for depressed mood and delinquency such as aggressive behavior problems and low academic achievement. Two-level hierarchical generalized linear models of concurrent relations indicated that depressed mood predicted concurrent variety of delinquent acts, and more variety of delinquent acts predicted concurrent depressed mood, even after controlling common risk factors. Longitudinal analyses indicated that after controlling for common risk factors, depressed mood had a more robust effect on delinquency variety trajectories than delinquency variety had on depressed mood trajectories. Time-averaged depressed mood significantly predicted a more positive rate of change in delinquency variety across time. Baseline delinquency variety predicted baseline depressed mood and time-averaged delinquency variety predicted a more positive rate of change in depressed mood; however, both effects were marginally significant. Implications of the results for theory and intervention are discussed.     

Aging and functional spatial relations in comprehension and memory

Previous research has suggested that, relative to younger adults, older adults devote a greater proportion of their discourse processing to the situation model level. The current experiment assessed whether this is due, in part, to a preserved ability to focus on functionally appropriate information. The focus here was on spatial relations. Both reading time and recognition data showed superior performance for functional over nonfunctional information, and this functional effect was similar in younger and older adults. This is consistent with the idea that older adults' ability to process information at the situation model level is relatively well preserved.     

Visual perspective taking for avatars in a Simon task

In modern digital applications, users often interact with virtual representations of themselves or others, called avatars. We examined how these avatars and their perspectives influence stimulus–response compatibility in a Simon task. Participants responded to light/dark blue stimuli with left/right key presses in the presence of a task-irrelevant avatar. Changes in stimulus–response compatibility were used to quantify changes in the mental representation of the task and perspective taking toward this avatar. Experiments 1 and 2 showed that perspective taking for an avatar occurred in orthogonal stimulus–response mappings, causing a compatibility effect from the avatar’s point of view. In the following two experiments we introduced a larger variety of angular disparities between the participant and avatar. In Experiment 3, the Simon effect with lateralized stimulus positions remained largely unaffected by the avatar, pointing toward an absence of perspective taking. In Experiment 4, after avatar hand movements were added in order to strengthen the participants’ sense of agency over the avatar, a spatial compatibility effect from the avatar’s perspective was observed again, and hints of the selective use of perspective taking on a trial-by-trial basis were found. Overall, the results indicate that users can incorporate the perspective of an avatar into their mental representation of a situation, even when this perspective is unnecessary to complete a task, but that certain contextual requirements have to be met.     

Knowledge level learning and the power law: A soar model of skill acquisition in scheduling

Zusammenfassung. Das hier vorgestellte Modell lernt graduell, Planungsaufgaben aus der Klasse der Maschinenbelegungsprobleme (job-shop-scheduling problems) zu lösen. Mit Hilfe des Chunking-Mechanismus von Soar wird episodisches Wissen über die Belegungsreihenfolge von Aufträgen auf Maschinen memoriert. Bei der Entwicklung des Modells wurden zahlreiche qualitative (z. B. Transfereffekte) und quantitative Befunde (z. B. Bearbeitungszeiten) aus einer früheren empirischen Untersuchung berücksichtigt. In einer Validierungsstudie wurden dieselben Aufgaben von 14 Probanden und dem Modell bearbeitet. Die Passung von Simulationsdaten und empirischen Ergebnissen fiel insgesamt gut aus. Allerdings löst das Modell die Aufgaben schneller und zeigt auch einen etwas besseren Lernverlauf als die Probanden. Das Modell liefert eine Erklärung für das Rauschen, das typischerweise bei Bearbeitungszeiten zu beobachten ist: es handelt sich um erworbenes Wissen, das mehr oder weniger gut und auch unterschiedlich häufig auf neue Situationen übertragen wird. Der Lernverlauf der Probanden entspricht nur für aggregierte Daten einer Potenzfunktion (power law). Der vorgestellte Mechanismus zeigt, wie ein symbolisches Modell der Informationsverarbeitung graduelle Verhaltensänderungen generiert und wie der offensichtliche Erwerb allgemeiner Prozeduren ohne explizites Lernen von deklarativen Regeln erfolgen kann. Es wird nahegelegt, daß es sich hier um die Modellierung einer Form impliziten Lernens handelt. Summary. The model presented here gradually learns how to perform a job-shop scheduling task. It uses Soar's chunking mechanism to acquire episodic memories about the order to schedule jobs. The model was based on many qualitative (e.g., transfer effects) and quantitative (e.g., solution time) regularities found in previously collected data. The model was tested with new data where scheduling tasks were given to the model and to 14 subjects. The model generally fit these data with the restrictions that the model performs the task (in simulated time) faster than the subjects, and its performance improves somewhat more quickly than the subjects' performance. The model provides an explanation of the noise typically found in problem solving times - it is the result of learning actual pieces of knowledge that transfer more or less to new situations but rarely by an average amount. Only when the data are averaged (i.e., over subjects) does the smooth power law appear. This mechanism demonstrates how symbolic models can exhibit a gradual change in behavior and how the apparent acquisition of general procedures can be performed without resorting to explicit declarative rule generation. We suggest that this may represent a type of implicit learning.