It looks easy! Heuristics for combinatorial optimization problems

Human performance on instances of computationally intractable optimization problems, such as the travelling salesperson problem (TSP), can be excellent. We have proposed a boundary-following heuristic to account for this finding. We report three experiments with TSPs where the capacity to employ this heuristic was varied. In Experiment 1, participants free to use the heuristic produced solutions significantly closer to optimal than did those prevented from doing so. Experiments 2 and 3 together replicated this finding in larger problems and demonstrated that a potential confound had no effect. In all three experiments, performance was closely matched by a boundary-following model. The results implicate global rather than purely local processes. Humans may have access to simple, perceptually based, heuristics that are suited to some combinatorial optimization tasks.     

The scenic function of the ego and its role in symptom and character formation1

The author argues that the scenic function of the ego permits the situationally appropriate representation of an unconscious, infantile configuration – that is, of a relatively stable, personality‐based drive scene having the same status as latent dream thoughts. The products of conflict elaboration (symptoms, etc.) are manifested in different ways in accordance with the conditions of the relevant situation. The contents of the drive scene are created by the psychical apparatus on the basis of infantile perceptions and are revealed in screen memories. The capacity for situationally appropriate representation is apparently bound up with the mobile drive, including its narcissistic transformations. Desexualization (in the sense of neutralization) renders scenic elaboration impossible. The drive derivatives withdrawn from the scenic configuration contribute to ego organization and the formation of character traits, which no longer vary according to the situation, but can only be modified by a change in personality structure itself. It is as yet unclear whether a process of resexualization can make them amenable once more to analytic work. The form of narcissistic libido that can assume a scenic configuration is closely related to primary narcissism. Its manifestations, which may likewise emerge in situation‐dependent symptom formations, appear accessible to analysis.     

Stimulus generalization as a function of the delay between training and testing procedures: a reevaluation

Three groups of 12 pigeons each were trained to discriminate between lights of 550 mμ (S^D), correlated with 1-min variable-interval reinforcement and 570 mμ (S^Δ), correlated with extinction. Group A was tested for wavelength generalization in extinction 1 min after meeting the discrimination criterion; Group B was tested 24 hr later; Group C was tested 24 hr later after a 3-min (reinforced) warm-up with the S^D. The post-discrimination gradient of Group B was significantly flatter and showed significantly greater area shift than that of Groups A and C. The gradient of Group C was similar to that of Group A, indicating that the warm-up eliminated the effect of the delay period.     

Early top-down control over saccadic target selection: Evidence from a systematic salience difference manipulation

Previous research on the contribution of top-down control to saccadic target selection has suggested that eye movements, especially short-latency saccades, are primarily salience driven. The present study was designed to systematically examine top-down influences as a function of time and relative salience difference between target and distractor. Observers performed a saccadic selection task, requiring them to make an eye movement to an orientation-defined target, while ignoring a color-defined distractor. The salience of the distractor was varied (five levels), permitting the percentage of target and distractor fixations to be analyzed as a function of the salience difference between the target and distractor. This analysis revealed the same pattern of results for both the overall and the short-latency saccades: When the target and distractor were of comparable salience, the vast majority of saccades went directly to the target; even distractors somewhat more salient than the target led to significantly fewer distractor, as compared with target, fixations. To quantify the amount of top-down control applied, we estimated the point of equal selection probability for the target and distractor. Analyses of these estimates revealed that, to be selected with equal probability to the target, a distractor had to have a considerably greater bottom-up salience, as compared with the target. This difference suggests a strong contribution of top-down control to saccadic target selection—even for the earliest saccades.     

Motherhood and Counselor Education: Experiences With Work–Life Balance

Female professors with children continue to experience institutional and cultural barriers in academia. This article situates the experiences of counselor educator mothers in the context of current trends in academia and research related to mothers in the workforce.     

Musical training generalises across modalities and reveals efficient and adaptive mechanisms for reproducing temporal intervals

Expert musicians are able to time their actions accurately and consistently during a musical performance. We investigated how musical expertise influences the ability to reproduce auditory intervals and how this generalises across different techniques and sensory modalities. We first compared various reproduction strategies and interval length, to examine the effects in general and to optimise experimental conditions for testing the effect of music, and found that the effects were robust and consistent across different paradigms. Focussing on a ‘ready-set-go’ paradigm subjects reproduced time intervals drawn from distributions varying in total length (176, 352 or 704 ms) or in the number of discrete intervals within the total length (3, 5, 11 or 21 discrete intervals). Overall, Musicians performed more veridical than Non-Musicians, and all subjects reproduced auditory-defined intervals more accurately than visually-defined intervals. However, Non-Musicians, particularly with visual stimuli, consistently exhibited a substantial and systematic regression towards the mean interval. When subjects judged intervals from distributions of longer total length they tended to regress more towards the mean, while the ability to discriminate between discrete intervals within the distribution had little influence on subject error. These results are consistent with a Bayesian model that minimizes reproduction errors by incorporating a central tendency prior weighted by the subject's own temporal precision relative to the current distribution of intervals. Finally a strong correlation was observed between all durations of formal musical training and total reproduction errors in both modalities (accounting for 30% of the variance). Taken together these results demonstrate that formal musical training improves temporal reproduction, and that this improvement transfers from audition to vision. They further demonstrate the flexibility of sensorimotor mechanisms in adapting to different task conditions to minimise temporal estimation errors.     

Zuschriften an die Herausgeber

Ohne Zusammenfassung     

Attentional Orienting in Two-dimensional Space

This paper examines how the covert orienting of spatial attention affects motor responses to visual stimuli. Premotor theories, as well as hemi-field inhibition accounts of visual attention predict an increase in response times when a target stimulus appears in the opposite direction to a spatial cue. Some models also suggest that this meridional effect should be increased across oblique meridians. Two types of cue (central and peripheral) were used to orient attention towards locations prior to the onset of visual targets. Simple manual (press button) and saccadic responses were measured. No meridional effects were found with peripheral cues, whereas central cueing produced meridional effects across all meridians. Cueing effects did not vary significantly with two-dimensional axis for either manual or saccadic responses. Increases in response time with cue-target distance were found for both response and cue types. For saccades, distance gradients were shallower moving distally rather than proximally from the cued position. However, simple manual responses did not show this asymmetry. Orienting to central cues also modulated the amplitude of saccades. The results are consistent with an effect of attentional cues in oculomotor centres as well as the existence of actiondependent attentional representations. However, it is proposed that, rather than reflecting oculomotor programming, meridional effects arise from a directional organization within spatio-cognitive representations.     

Does Guilt Motivate Prayer?

We recruited 110 college students for an experimental investigation of the role of guilt in motivating religious behavior. We induced guilt in half of the participants before asking all subjects to indicate their current interest in prayer. Overall, participants in the guilt condition were more interested in praying, but this effect was not observed among those high in grandiose narcissism. Our findings make a contribution not only to the study of the role that emotions have in motivating religious behavior, but also to the study of narcissists’ susceptibility to guilt.