The pigeon's discrimination of visual entropy: a logarithmic function

We taught 8 pigeons to discriminate 16-icon arrays that differed in their visual variability or "entropy" to see whether the relationship between entropy and discriminative behavior is linear (in which equivalent differences in entropy should produce equivalent changes in behavior) or logarithmic (in which higher entropy values should be less discriminable from one another than lower entropy values). Pigeons received a go/no-go task in which the lower entropy arrays were reinforced for one group and the higher entropy arrays were reinforced for a second group. The superior discrimination of the second group was predicted by a theoretical analysis in which excitatory and inhibitory stimulus generalization gradients fall along a logarithmic, but not a linear scale. Reanalysis of previously published data also yielded results consistent with a logarithmic relationship between entropy and discriminative behavior.     

Reaching while calculating: scheduling of cognitive and perceptual-motor processes

To address the neglected question of how cognitive and perceptual-motor processes are coordinated, the authors asked participants to move a cursor from one target to another to reveal operators and operands for a running arithmetic task. In Experiment I performance on this task was compared with performance on tasks requiring only aiming or only arithmetic. Aiming was faster in the aiming-only task than in the combined task. More importantly, times for steps requiring calculation were equivalent in the combined and arithmetic-only tasks. The results from this and a second experiment suggest that participants slowed their aiming to allow calculations to be completed before subsequent targets were entered. As a whole, the results suggest that cognitive and perceptual-motor processes are coordinated through scheduling.     

Stimulus control by same-versus-different relations among multiple visual stimuli

The authors devised a go/no-go discrimination learning task that allowed but did not require pigeons to report (a) from which of 2 different sets a collection of visual items was drawn and (b) the relations between or among the items as being the same as or different from one another. The results of 2 experiments using this task disclosed stimulus control by the particular items in the arrays and by the same-different relations exemplified by those items. Relational and item control depended on how many items were in the arrays. Same-different discrimination was evident with 2-item displays, but it was much stronger with 6 or more items. These findings help to define the substrates of advanced conceptual behavior.     

The eyebrow frown: a salient social signal

Seven experiments investigated the finding that threatening schematic faces are detected more quickly than nonthreatening faces. Threatening faces with v-shaped eyebrows (angry and scheming expressions) were detected more quickly than nonthreatening faces with inverted v-shaped eyebrows (happy and sad expressions). In contrast to the hypothesis that these effects were due to perceptual features unrelated to the face, no advantage was found for v-shaped eyebrows presented in a nonfacelike object. Furthermore, the addition of internal facial features (the eyes, or the nose and mouth) was necessary to produce the detection advantage for faces with v-shaped eyebrows. Overall, the results are interpreted as showing that the v-shaped eyebrow configuration affords easy detection, but only when other internal facial features are present.     

Concurrent learning of temporal and spatial sequences

In a serial reaction time task, stimulus events simultaneously defined spatial and temporal sequences. Responses were based on the spatial dimension. The temporal sequence was incidental to the task, defined by the response-to-stimulus intervals in Experiment 1 and stimulus onset asynchronies in Experiment 2. The two sequences were either of equal length and correlated or of unequal length. In both experiments, spatial learning occurred regardless of sequence length condition. In contrast, temporal learning occurred only in the correlated condition. These results suggest that timing is an integrated part of action representations and that incidental learning for a temporal pattern does not occur independently from the action. Interestingly, sequence learning was enhanced in the correlated condition, reflecting the integration of spatial-temporal information.     

Restless legs syndrome and drug-induced akathisia in headache patients

The purpose of the research presented in this article was to characterize restless leg syndrome (RLS) in a headache population and correlate treatment induced risks with dopamine blockers. Fifty patients with severe headache who were admitted to an outpatient infusion center were enrolled. The diagnosis of RLS was established using the International Restless Leg Syndrome Study Group criteria. Patients were screened for baseline akathisia using an akathisia scale and reexamined for akathisia after receiving intravenous infusion with one of four dopamine receptor blocking agents as treatment for their headaches. A change from baseline to post-infusion assessment of two points on a global assessment of akathisia was considered positive for drug-induced akathisia. Our results indicated that 41 (82%) of patients had episodic or chronic migraine. The rest had new daily persistent headache, cluster, or posttraumatic headache. Seventeen subjects (34%) met the criteria for RLS. Nineteen (38%) of the subjects developed drug-induced akathisia. Thirteen (76.5%) of the subjects with RLS developed akathisia compared with only 6 of the 33 (18.2%) without RLS (P<.0001). Finally, we concluded that headache patients with RLS are at a greatly increased risk of developing drug-induced akathisia when treated with intravenous dopamine receptor blocking agents.     

Social preferences of developing guinea pigs (Cavia porcellus) from the preweaning to the periadolescent periods

Preference tests in a novel environment (Experiment 1) and unobtrusive observations in a specialized living environment (Experiment 2) examined the attractiveness of various classes of conspecifics for maturing guinea pigs (Cavia porcellus). It was found that (a). the young continued to remain near the mother well beyond weaning; (b). there was increased time spent with unrelated adult females, but not males, after weaning; (c). male and female offspring behaved similarly; and (d). littermates spent considerable time with each other. These results provide no evidence that guinea pigs approaching sexual maturity begin to associate preferentially with novel animals or potential breeding partners. Choices were largely predictable from earlier findings of the ability of various classes of conspecifics to reduce hypothalamic-pituitary-adrenal activity of the young.     

Dissociation of pure korean words and Chinese-derivative words in phonological dysgraphia

Phonological dysgraphia is a writing impairment, characterized by marked disability to spell pronounceable pseudo-words as opposed to relatively mild reduction in ability to spell real words. Within the realm of Korean vocabulary, there are two categories of real words: pure Korean words and Chinese-derivative words. We present a patient with a history of CVA, resulting in phonological dysgraphia and, further, a dissociated performance in the aforementioned two categories of real words. It is suggested that the lexicon for pure Korean words is segregated from that for Chinese-derivative words.     

Predictors of Managerial Performance: More Than Cognitive Ability

This study investigated the discriminant validity of cognitive ability, managerial potential, fear of negative evaluation, interaction anxiousness, and audience anxiousness as predictors of managerial performance. As hypothesized cognitive ability significantly predicted only thinking and knowledge criteria. However, managerial potential was significantly correlated with all the criteria. As predicted, fear of negative evaluation predicted thinking and knowledge criteria, interaction anxiousness, and audience anxiousness. In turn, as predicted, interaction anxiousness significantly predicted interpersonal behavior and audience anxiousness significantly predicted communication behavior. Managerial potential and fear of negative evaluation were the only two predictors that were significantly correlated with overall performance.     

A first impression of the future

We offer a response to six commentaries on our target article ‘Understanding trait impressions from faces’. A broad consensus emerged with authors emphasizing the importance of increasing the diversity of faces and participants, integrating research on impressions beyond the face, and continuing to develop methods needed for data-driven approaches. We propose future directions for the field based on these themes.