Foraging and associative learning of visual signals in a parasitic wasp

To cope with environmental variability, animals should gather and use information to reduce uncertainty. In insect parasitoids, associative learning has been widely documented in the context of host foraging. However, despite its potential adaptive value, the insect food searching strategy and cues used to search are poorly understood. In this study, we examined the ability of hymenopteran Venturia canescens females to associate food to a visual cue. To broaden the scope of our results, experiments were performed with both arrhenotokous (sexual) and thelytokous (asexual) individuals. The wasps showed innate attraction for yellow and orange stimuli when presented versus blue stimuli. When trained to associate a food reward with one of the attractive colours (orange), they significantly moved from a distance towards the colour previously associated with food. The choice of the innately preferred colour (yellow) was not modified by associative learning. In the context of food foraging, this study is the first to show associative learning using visual stimuli in a parasitoid and active choice of this colour. This ability gives new insights concerning potential food sources for V. canescens in the field, since flowers are sugar sources, which emit colour signals.     

Measuring Daytime Drowsiness in Nursing Home Residents: The MSLT-NH

A standardized method of assessing daytime drowsiness in frail nursing home residents has not been previously available. We present here the development and test characteristics of an instrument to measure daytime drowsiness in nursing home residents with cognitive and functional impairment, the Multiple Sleep Latency Test-Nursing Home (MSLT-NH). In a standardized manner, the resident is tested three times in one day (at 9 a.m., 11 a.m., and 1 p.m.) to measure the amount of time until the subject falls asleep. The average sleep latency (minutes to fall asleep) is the measure of interest. We tested the MSLT-NH in 95 residents from six community nursing homes in the Los Angeles area (82% of subjects were female; 81% were white, mean age was 86.6 years and mean score on the Mini-Mental State Examination [MMSE] was 9.4). Interrater reliability of the MSLT-NH was quite good (correlations between raters ranged from 0.98 to 0.99; all p values were <.0001). Validity was assessed by comparing MSLT-NH results to simultaneous wrist activity estimation of sleep, and by comparing MSLT-NH findings to results from nighttime sleep estimation by wrist actigraphy the night prior to MSLT-NH. The percent agreement between MSLT-NH and wrist actigraph ranged from 77% to 79% MSLT-NH results were significantly associated with peak duration of nighttime sleep episodes the night prior to testing. The MSLT-NH was also quite acceptable for use in the NH setting. In conclusion, we have developed a promising measure of daytime drowsiness in NH residents. Further testing will help establish whether this test is a clinically useful measure of daytime drowsiness from medications or other conditions in the NH setting.     

Response demands and the recruitment of heuristic strategies in syllogistic reasoning

Two experiments investigated whether dealing with a homogeneous subset of syllogisms with time-constrained responses encouraged participants to develop and use heuristics for abstract (Experiment 1) and thematic (Experiment 2) syllogisms. An atmosphere-based heuristic accounted for most responses with both abstract and thematic syllogisms. With thematic syllogisms, a weaker effect of a belief heuristic was also observed, mainly where the correct response was inconsistent with the atmosphere of the premises. Analytic processes appear to have played little role in the time-constrained condition, whereas their involvement increased in a self-paced, unconstrained condition. From a dual-process perspective, the results further specify how task demands affect the recruitment of heuristic and analytic systems of reasoning. Because the syllogisms and experimental procedure were the same as those used in a previous neuroimaging study by Goel, Buchel, Frith, and Dolan (2000), the result also deepen our understanding of the cognitive processes investigated by that study.     

An interactive multiobjective procedure for selecting medium-term countermeasures after nuclear accidents

This paper presents a methodology for supporting medium-term decisions in the context of nuclear accidents. An interactive procedure based on a multiobjective linear model is introduced, allowing the set of feasible strategies to be explored. This procedure enables the users to express preferences on both criterion values and the structure of the strategies. Additional flexibility is provided by the possibility of integrating evolutive constraints during the decision process. © 1998 John Wiley & Sons, Ltd.     

A solution to the many attitudes problem

Philosophical Studies - According to noncognitivism, normative beliefs are just desire-like attitudes. While noncognitivists have devoted great effort to explaining the nature of normative belief,...     

Correlational analyses of explicit and implicit memory performance

Sixty-four subjects were administered two tests of explicit memory (selective recall and recognition) and four tests of implicit memory (identification in a perceptual clarification procedure, word-fragment completion, tachistoscopic identification, and anagram solution). Each test drew on a different subset of a long list of previously displayed words. Although the four implicit memory tests showed sizable priming effects, correlational and factor analyses showed striking dissociations. On the one hand, performance on the perceptual clarification procedure and word-completion tests were related to one another, as well as to recall and recognition. On the other hand, performance on tachistoscopic identification and anagram solution were related to one another, but not to the measures for the other tasks. A framework is proposed to reconcile these new results with current knowledge on the explicit/implicit memory distinction, based in particular on studies of amnesic subjects. It is argued that a small number of tasks, especially tachistoscopic identification, may serve as relatively uncontaminated and ubiquitous indicators of implicit memory. However, explicit remembering could affect performance in so-called implicit memory tasks that allow for a strategy of controlled selection of candidate responses from accumulating cues, in experimental conditions that make the explicit remembering of relevant events possible.     

The relation between formal operational reasoning and academic course selection and performance among college freshmen and sophomores

The significance of Inhelder and Piaget's (1958) construct of “formal operations” depends in part on establishing the extent to which formal operations have real-world relevance beyond the narrow domain of assessment situations in which Inhelder and Piaget studied them. The present research investigates this question by examining the effect of exhibiting a concrete versus formal operational level of reasoning in an isolation of variables task on academic program selection and performance of beginning college students over a two-year period. Students who reasoned at the concrete operational level did not differ from students matched on ACT scores who reasoned at a formal operational level with respect to either number of college credits obtained or overall grade point average. When courses were broken down into three categories, however, “formals” took significantly more science/math courses and received significantly higher grades in them. No differences were found in the other two categories: liberal arts/social sciences or activities/vocational courses. A further study of beginning college students already enrolled in science/math courses confirmed that very few concrete operational reasoners were present in these courses, suggesting that a process of self-selection is in operation.     

A nonlinear dynamic artificial neural network model of memory

Nonlinearity and dynamics in psychology are found in various domains such as neuroscience, cognitive science, human development, etc. However, the models that have been proposed are mostly of a computational nature and ignore dynamics. In those models that do include dynamic properties, only fixed points are used to store and retrieve information, leaving many principles of nonlinear dynamic systems (NDS) aside; for instance, chaos is often perceived as a nuisance. This paper considers a nonlinear dynamic artificial neural network (NDANN) that implements NDS principles while also complying with general neuroscience constraints. After a theoretical presentation, simulation results will show that the model can exhibit multi-valued, fixed-point, region-constrained attractors and aperiodic (including chaotic) behaviors. Because the capabilities of NDANN include the modeling of spatiotemporal chaotic activities, it may be an efficient tool to help bridge the gap between biological memory neural models and behavioral memory models.     

The influence of spatial context and the role of intentionality in the interpretation of animacy from motion

We present three experiments investigating how spatial context influences the attribution of animacy to a moving target. Each of our displays contained a moving object (the target) that might, depending on the way it moved, convey the impression that it was alive (animate). We investigated the mechanisms underlying this attribution by manipulating the nature of the spatial context surrounding the target. In Experiment 1, the context consisted of a simple static dot (the foil), whose position relative to the target's trajectory was manipulated. With some foil positions--for example, when the foil was lying along the path traveled by the target--animacy judgments were elevated relative to control foil locations, apparently because this context supported the impression that the target was "reacting to" or was in some other way mentally influenced by the foil. In Experiment 2, contexts consisted of a static oriented rectangle (the "paddle"). On some trials, the target collided with the paddle in a way that seemed to physically account for the target's motion pattern (in the sense of having imparted momentum to it); this condition reduced animacy ratings. Experiment 3 was similar, except that the paddles themselves were in motion; again, animacy attribution was suppressed when the target's motion seemed to have been caused by a collision with the paddle. Hence, animacy attributions can be either elevated or suppressed by the nature of the environment and the target's interaction with it. Animacy attribution tracks intentionality attribution; contrary to some earlier proposals, we conclude that attributing animacy involves, and may even require, attributing to the target some minimal mental capacity sufficient to endow the target with intentionality.