An automatic micropipette fluid dispenser

An automatic device for repeated dispensation of a precisely controlled amount of fluid is described. The device employs a repeating micropipette powered by an electric motor geared to a rack-and-pinion drive. In our particular application, thirsty rats work for 0.2-ml shots of water delivered to a metal spout connected to a drinkometer circuit. This arrangement permits the recording of both volumetric intake and the number of licks directed at the spout.     

Social Support. Physiological Processes, and Health

Social relationships serve important functions in people's everyday lives. Epidemiological research indicates that supportive relationships may also significantly protect individuals from various causes of mortality, including cardiovascular disease. An important issue is how social support influences such long-term health outcomes. In this article, we review evidence indicating that social support may influence mortality via changes in the cardiovascular, endocrine, and immune systems. These data suggest that it may be worthwhile to incorporate social-support interventions in the prevention and treatment of physical health problems.     

Complex analyses of variance: General problems

Problems in applying the analysis of variance are discussed. Emphasis is placed on using the technique to understand the data. The scale of the dependent variable is important for the analysis. Crossed and nested categories must be recognized. The error terms in the analysis depend on whether the classes of each independent variable are (1) all out of a few or (2) a few out of many. To simplify the analysis, mean squares should be aggregated with their error term when they are less than twice its size. An illustrative example is discussed in detail.Prepared in connection with research sponsored in part by the Office of Naval Research, in part by the Educational Testing Service, and in part by Lincoln Laboratory, a center for research operated by Massachusetts Institute of Technology with the joint support of the U. S. Army, Navy, and Air Force.     

Discounting and the role of the relation between causes

This research investigates how the relation between two causes (i.e. whether they co‐occur or not) affects the likelihood to discount one of them. In two experiments, two causes were either systematically paired together (positive relation), were paired with many other causes (independent relation), or were never paired together (negative relation). The results indicate that discounting of one of the causes (target cause) depends on the relation with the other cause (alternative cause) and the order in which the alternative cause was presented and produced the outcome alone. If information on the independent outcome of the alternative cause came prior to the joint outcome of the alternative and target cause (forward order), then discounting of the target cause occurred regardless of the relation between the two causes. If, however, information on the independent outcome of the alternative cause came after the joint outcome of the alternative and target cause (backward order), then discounting of the target cause occurred mainly when there was a positive or negative relation between the causes, but not when there was an independent relation. The degree of backward discounting given a positive or negative relation was largely identical. These results are consistent with the retrospective revaluation hypothesis of Dickinson and Burke ( 1996 ) and shed new light on the role of the relation between causes on discounting. Copyright © 2004 John Wiley & Sons, Ltd.     

Selection Test Anxiety: Investigating applicants' self‐ vs other‐referenced anxiety in a real selection setting

Test anxiety has received limited attention in personnel selection research, although it may impair the test performance of applicants. This paper describes the development and validation of a new two‐dimensional measure of applicants' test anxiety, namely the Self‐ versus Other‐Referenced Anxiety Questionnaire (SOAQ), that embeds worrisome cognitions of anxious applicants in the social evaluative context of ‘self’ (Self‐Referenced Anxiety) and ‘significant others’ (Other‐Referenced Anxiety). An exploratory factor analysis (calibration sample), followed by a confirmatory factor analysis (validation sample) and correlations with several proximal and distal theoretical constructs indicated satisfactory psychometric properties and construct validity for both SOAQ scales. Structural equation modeling further showed a differential impact of Self‐ and Other‐Referenced Anxiety on applicants' test performance within a real personnel selection context. The scientific and practical relevance of these findings are discussed.     

Applicant Selection Expectations: Validating a multidimensional measure in the military

Research has suggested the importance of applicants' expectations of forthcoming selection procedures in predicting how applicants react to selection procedures. Validated measures of selection expectations are still scarce, however. This study reports on the validation of the Applicant Expectation Survey (AES), intended to measure applicants' expectations of forthcoming selection procedures. The AES was validated using three military applicant samples and showed sound psychometric properties (i.e., reliability, measurement invariance, discriminant validity) for a five‐factorial oblique structure consisting of 26 items. The five factors (i.e., Warmth/respect, Chance to demonstrate potential, Difficulty of faking, Unbiased assessment, Feedback) were positively related to several organizational outcome measures and to applicants' perceptions of the selection procedure, providing evidence for the predictive validity of the AES.     

Conscious and unconscious proportion effects in masked priming

The global neuronal workspace theory [Dehaene, S., & Naccache, L. (2001). Towards a cognitive neuroscience of consciousness: basic evidence and a workspace framework. Cognition, 79, 1–37.] proposes that it is impossible for an unconscious stimulus to be used strategically to enhance task performance (bottom–up effect), while a fully consciously perceived stimulus can be used to improve task performance (top–down effect). Two experiments were designed to investigate these hypotheses. In a first experiment we investigated whether a manipulation of the proportion of Arabic/number word targets had a top–down effect. Since the subjects were fully aware of the target, we expected that this manipulation could be used to enhance task performance. In a second experiment we determined whether a manipulation of the proportion of Arabic/number word primes had a bottom–up effect. Since the subjects were unaware of the prime, we hypothesized that they would be unable to use the manipulation to enhance task performance and therefore the manipulation would have no effect. Both hypotheses were largely confirmed.     

The predictive value of numerical magnitude comparison for individual differences in mathematics achievement

Although it has been proposed that the ability to compare numerical magnitudes is related to mathematics achievement, it is not clear whether this ability predicts individual differences in later mathematics achievement. The current study addressed this question in typically developing children by means of a longitudinal design that examined the relationship between a number comparison task assessed at the start of formal schooling (mean age = 6 years 4 months) and a general mathematics achievement test administered 1 year later. Our findings provide longitudinal evidence that the size of the individual’s distance effect, calculated on the basis of reaction times, was predictively related to mathematics achievement. Regression analyses showed that this association was independent of age, intellectual ability, and speed of number identification.