Recall suffers from collaboration: Joint recall effects of friendship and task complexity

Collaborative recall in episodic memory tasks was investigated in two experiments. The experiments were explicitly designed to investigate how the interaction between two subjects influences group productivity. Subjects were requested to recall twice, first individually, and second, in different subject constellations (individually, or in dyads, as friends or non-friends). Experiment 1 employed free recall of words and story recall. In Experiment 2, a video-taped lecture on child development was recalled. The observed score at the second recall (Recall 2) was compared with the nominal predicted score, based on the initial recall. The results of the experiments are summarized and discussed in four clusters: (1) observed productivity for dyads never reached their predicted potential; (2) the negative effects of collaborative recall can be reduced; (3) friends rather than non-friends, and complex rather than simple tasks, reduce the loss in productivity; and (4) the data also suggest that encoding alone is superior to collaborative encoding.     

The Formal Characteristics of Behaviour—Temperament Inventory (FCB—TI): Validity studies

A psychometric study has been conducted with the aim of testing the validity of the Formal Characteristics of Behaviour—Temperament Inventory (FCB—TI). FCB—TI has been constructed to measure six temperament traits according to the Regulative Theory of Temperament (RTT): Briskness, Perseverance (referring to the temporal aspect of behavior), Sensory Sensitivity, Emotional Reactivity, Endurance, and Activity (referring to the energetic characteristics of behaviour). These traits have been compared with other temperament as well as personality dimensions. The following measures were used: PTS, EAS—TS, DOTS—R, EPQ—R, SSS—V, 16PF, and NEO-FFI. The study was conducted on samples consisting of over 1500 subjects with satisfactory balanced gender ratio (about 50 per cent), and with a broad range of age (from 15 to 77 years), representing a variety of professions and educational levels. The correlational and factor analytic findings are presented; these show high theoretical validity of the FCB—TI scales, except the Sensory Sensitivity scale. In the discussion some conclusions concerning the revision of the structure of temperament have been suggested.     

Modifications of the Poggendorff effect as a function of random dot textures between the verticals

In the present research, we investigated the modification of the strength of the Poggendortf illusion as a function of different densities ofrandom dot textures failing the space between the verticals. The results ofExperiment 1 show that the illusory effect is a nonlinear function ofthe texture parameterr, the ratio of black pixels to white and black pixels, with a minimum forr=0.5, approximately, and a maximum forr=0 andr=1. The results may be interpreted by an analytical model of perceptual space dynamics, in which the effect dependson the amount of interaction between points of different light intensity. A computer simulation performed by applying the analytical model to different values ofr shows a good agreement between the predictions and the experimental data. To test the hypothesis underlying the model, a second experiment was carried out to measure the magnitude of the expansion ofthe space between the verticals as a function of the parameterr. The results are consistent with the hypothesis of the model. The overall data are discussed in terms of their implications on various theories proposed for the Poggeadorff illusion.     

De Finetti's earliest works on the foundations of probability

Bruno de Finetti's earliest works on the foundations of probability are reviewed. These include the notion of exchangeability and the theory of random processes with independent increments. The latter theory relates to de Finetti's ideas for a probabilistic science more generally. Different aspects of his work are united by his foundational programme for a theory of subjective probabilities.This work would not have been possible in its present form without the generous help of Prof. Maria Carla Galavotti. For several years, she has unfailingly answered all my requests for papers difficult of access, and discussed the details of interpretation as well as the philosophy of probability in general. To her I express my gratitude for everything.     

Effects of diagnostic classification systems on clinical hypothesis-generation

In this study it was determined whether (a) classification as opposed to absence of classification has an effect on the quality of clinical hypotheses (b) the DSM-III-R and the CBCL have a different effect on the quality of clinical hypotheses, and (c) the potential difference between the DSM-III-R and the CBCL is moderated by the different number of syndromes identified by these systems. To investigate these questions, an experiment was conducted in which 86 clinicians generated hypotheses for six cases. The clinicians were divided into a DSM-III-R, a CBCL, and a control group. Of the six cases, two were classified by both classification systems as one syndrome, two were classified as one syndrome by the DSM-III-R but as two syndromes by the CBCL, and two were classified as two syndromes by the DSM-III-R but as one syndrome by the CBCL. The quality of the hypotheses was determined by means of four dependent variables selected from an overview of qualitative criteria: explanatory value, redundancy, possibility of operationalization, and specificity. No differences between the CBCL and the control groups were found. The DSM group performed better than the control group regarding explanatory value and redundancy. The DSM-III-R group also scored better than the CBCL group regarding explanatory value, particularly when the number of identified syndromes was two for the CBCL and one for the DSM-III-R.     

An injection olfactometer for humans and a new method for the measurement of the shape of the olfactory pulse

An injection olfactometer for human psychophysical experiments is described. The olfactometer is capable of presenting, either mono- or birhinally, single odorants and binary mixtures. The pulse form of the olfactory stimulus at the exit of the olfactometer approaches a rectangular form, which makes the olfactometer well suited for olfactory reaction time measurements. Since stimulation periods are independent of the subject’s inhalation, time-intensity measurements over prolonged periods of time are possible as well. In the second part of this paper, a new technique is described for the measurement of the stimulus pulse form at the exit of the olfactometer.