The use of heuristics in intuitive mathematical judgment

Anecdotal evidence points to the use of beauty as an indication of truth in mathematical problem solving. In the two experiments of the present study, we examined the use of heuristics and tested the assumption that participants use symmetry as a cue for correctness in an arithmetic verification task. We manipulated the symmetry of sets of dot pattern addition equations. Speeded decisions about the correctness of these equations led to higher endorsements for both correct and incorrect equations when the addend and sum dot patterns were symmetrical. Therefore, this effect is not due to the fact that symmetry facilitates calculation or estimation. We found systematic evidence for the use of heuristics in solving mathematical tasks, and we discuss how these findings relate to a processing-fluency account of intuition in mathematical judgment.     

Social Identity and Social Exchange: Identification, Support, and Withdrawal From the Job

Integrating insights from the social exchange perspective and the social identity perspective, we propose that evaluations of support received from the organization and its representatives and organizational identification interact to predict withdrawal from the job. The relationship of support with withdrawal is proposed to be weaker the more strongly employees identify with the organization. This prediction was confirmed in 2 samples focusing on different operationalizations of support and withdrawal. Study 1 explored the interaction between organizational support and organizational identification in predicting turnover intention; Study 2 investigated the link between supervisor support and organizational identification and absenteeism. The present study thus yields evidence that may lay the groundwork for further integration of social exchange and social identity analyses of organizational behavior.     

Investigating a computerised test of the Stroop effect extended by inclusion of a third, more difficult task

A validation study of a computerised test recently developed involving the Stroop effect, extended here by inclusion of a third, more difficult test series, is presented. Three groups of men belonging to the Swedish armed forces and adjudged to differ in their qualifications (20, 32, and 19 men of levels 1, 2, and 3, respectively) and a fourth group of 18 men convicted of serious crimes of violence were given this test, termed the Stress Strategy Test. Discriminant analysis of the test's 12 variables (four for each of the three test series) yielded a discriminant power of 65% for the total group, highest for the level 1 group (80%) and for the nonmilitary group (72%), results substantially better than obtained for the original version of the test with use of similar subject groups.     

The other way around: does health predict perceived support?

The aim in this study was to identify predictors of perceived social support before and after cataract surgery. We hypothesized that physical (comorbidity and visual acuity) and mental (depressive symptoms) health indicators would be directly and indirectly (through actually received support) associated with perceived support. One hundred and thirty-six cataract patients (69% women; mean age = 71.6 years) completed questionnaires before and after cataract surgery. Results showed that received support partially mediated the association between depressive symptoms and perceived support. However, mental and physical health variables were also directly associated with perceived support. We conclude that health status might feedback to perceptions of available support.     

Effects of route guidance variable message signs (VMS) on driver behaviour

Effects of route guidance Variable Message Signs (VMS) on speed and route choice were investigated in a field study on two sites on motorways. Two VMS were used in the study, which displayed information about a closed road section downstream on the motorways and recommendations for alternative routes. Route choice, speed and braking behaviour were compared between vehicles approaching the VMS while they displayed messages and while they were left blank without message. There was high compliance with the messages on the VMS. About every fifth vehicle changed route choice according to the recommendation, and almost none drove as far as the closed road section. Speed measurements of 3342 vehicles showed large speed reductions, and video observations showed that large proportions of vehicles braked while approaching the VMS. The speed reductions and braking manoeuvres can partly be attributed to attention overload or distraction due to the information on the VMS. However, a proportion of the speed reductions was due to chain reactions where one vehicle braked and forced the following vehicles to brake or change lanes in order to avoid collisions. Safety problems may result directly from distraction, or indirectly from the reactions of the drivers to the distraction.     

On the optimality of serial and parallel processing in the psychological refractory period paradigm: Effects of the distribution of stimulus onset asynchronies

Within the context of the psychological refractory period (PRP) paradigm, we developed a general theoretical framework for deciding when it is more efficient to process two tasks in serial and when it is more efficient to process them in parallel. This analysis suggests that a serial mode is more efficient than a parallel mode under a wide variety of conditions and thereby suggests that ubiquitous evidence of serial processing in PRP tasks could result from performance optimization rather than from a structural bottleneck. The analysis further suggests that the experimenter-selected distribution of stimulus onset asynchronies (SOAs) influences the relative efficiency of the serial and parallel modes, with a preponderance of short SOAs favoring a parallel mode. Experiments varying the distribution of SOAs were conducted, and the results suggest that there is a shift from a more serial mode to a more parallel mode as the likelihood of short SOAs increases.     

Perceptual learning in auditory temporal discrimination: No evidence for a cross-modal transfer to the visual modality

Perceptual learning was used to study potential transfer effects in a duration discrimination task. Subjects were trained to discriminate between two empty temporal intervals marked with auditory beeps, using a twoalternative forced choice paradigm. The major goal was to examine whether perceptual learning would generalize to empty intervals that have the same duration but are marked by visual flashes. The experiment also included longer intervals marked with auditory beeps and filled auditory intervals of the same duration as the trained interval, in order to examine whether perceptual learning would generalize to these conditions within the same sensory modality. In contrast to previous findings showing a transfer from the haptic to the auditory modality, the present results do not indicate a transfer from the auditory to the visual modality; but they do show transfers within the auditory modality.