The psychophysics of sugar concentration discrimination and contrast evaluation in bumblebees

The capacity to discriminate between choice options is crucial for a decision-maker to avoid unprofitable options. The physical properties of rewards are presumed to be represented on context-dependent, nonlinear cognitive scales that may systematically influence reward expectation and thus choice behavior. In this study, we investigated the discrimination performance of free-flying bumblebee workers (Bombus impatiens) in a choice between sucrose solutions with different concentrations. We conducted two-alternative free choice experiments on two B. impatiens colonies containing some electronically tagged bumblebees foraging at an array of computer-automated artificial flowers that recorded individual choices. We mimicked natural foraging conditions by allowing uncertainty in the probability of reward delivery while maintaining certainty in reward concentration. We used a Bayesian approach to fit psychometric functions, relating the strength of preference for the higher concentration option to the relative intensity of the presented stimuli. Psychometric analysis was performed on visitation data from individually marked bumblebees and pooled data from unmarked individuals. Bumblebees preferred the more concentrated sugar solutions at high stimulus intensities and showed no preference at low stimulus intensities. The obtained psychometric function is consistent with reward evaluation based on perceived concentration contrast between choices. We found no evidence that bumblebees reduce reward expectations upon experiencing non-rewarded visits. We compare psychometric function parameters between the bumblebee B. impatiens and the flower bat Glossophaga commissarisi and discuss the relevance of psychophysics for pollinator-exerted selection pressures on plants.     

Operationalisierte Psychodynamische Diagnostik des Kindes- und Jugendalters

There are only a few studies focusing on the mental structure and its change in children and adolescents with psychiatric disorders. This study aimed at investigating change in the mental structure of children and adolescents over time. At intake 60 inpatients were interviewed with the operationalized psychodynamic diagnostic interview for children and adolescents (OPD-CA). After an average of 27 months 25 patients agreed on participating in the follow-up study. The OPD-CA was conducted again and the Kiddie-Sads present and lifetime version (Kiddie-Sads-PL) as well as parent-based ratings child behaviour checklist (CBCL) and strength and difficulties questionnaire (SDQ) were applied. A consensus rating of the OPD-CA was attained by three researchers well experienced with the use of the OPD-CA. The level of structural integration improved significantly, in particular in the dimensions “control” and “communication skills”. There were no significant changes in the dimension “self-perception/object-perception”. The improvement was also observable in parent-report questionnaires. This study makes a contribution to the idea that changes in the mental structure of children and adolescents can be shown and measured with the OPD-CA.     

Hangover sensitivity after controlled alcohol administration as predictor of post-college drinking

Predicting continued problematic levels of drinking after the early 20's could help with early identification of persons at risk. This study investigated whether hangover insensitivity could predict postcollege drinking and problems beyond the variance due to drinking patterns. In a preliminary study, 134 college seniors from a laboratory study of hangover (Time 1) were contacted and assessed 1-4 years (M = 2.3) later (Time 2). Hangover severity was studied after controlled alcohol administration to a specific dose while controlling sleep and environmental influences. Hangover severity at Time 1 was used to predict Time 2 drinking volume and problems while controlling for relevant demographics and Time 1 drinking volume. Hangover insensitivity at Time 1 tended to predict a clinical level of alcohol problems with a large statistical effect size. Hangover sensitivity also correlated positively with sensitivity to alcohol intoxication. Hangover severity did not predict future drinking volume. Hangover insensitivity correlates with insensitivity to intoxication and might predict more serious alcohol problems in the future, suggesting that a future larger study is warranted. Hangover insensitivity could result from physiological factors underlying low sensitivity to alcohol or risk for alcoholism.     

解读曼殊五部曲

苏曼殊是清末民初萃集革命与刨作于一身的“奇人异僧”。从革命的角度说,他意志坚定,积极投身于孙中山领导的资产阶级民主革命,为推翻清朝统治和袁世凯帝制尽心竭力;从创作的角度说,他多才多艺,以风格独特的诗歌、小说、散、翻译、绘画树帜坛,赢得生前和身后无数读的击节和赞赏;从身份的角度说,他是个亦僧亦俗、亦侠亦儒的革命和艺家。他曾获得的桂冠大体停留在不大反映本质的“诗僧”、“情僧”、“风流和尚”、“革命和尚”等一类称号上,然而随着这位传奇的历史人物的“真面目”越来越清晰呈现于世,而不再继续充当人们揣测的对象。     

Exploratory Factor Analysis With Small Sample Sizes

Exploratory factor analysis (EFA) is generally regarded as a technique for large sample sizes (N), with N = 50 as a reasonable absolute minimum. This study offers a comprehensive overview of the conditions in which EFA can yield good quality results for N below 50. Simulations were carried out to estimate the minimum required N for different levels of loadings (λ), number of factors (f), and number of variables (p) and to examine the extent to which a small N solution can sustain the presence of small distortions such as interfactor correlations, model error, secondary loadings, unequal loadings, and unequal p/f. Factor recovery was assessed in terms of pattern congruence coefficients, factor score correlations, Heywood cases, and the gap size between eigenvalues. A subsampling study was also conducted on a psychological dataset of individuals who filled in a Big Five Inventory via the Internet. Results showed that when data are well conditioned (i.e., high λ, low f, high p), EFA can yield reliable results for N well below 50, even in the presence of small distortions. Such conditions may be uncommon but should certainly not be ruled out in behavioral research data.