Calibration of probability assessments by professional blackjack dealers, statistical experts, and lay people

The question addressed in this study is whether experts are better calibrated than lay people. We investigated how well people are calibrated when they assess the probabilities of card combinations in the game of blackjack. Three groups of subjects were used: professional dealers, statistical experts, and control subjects. The results showed that experience and statistical expertise do not make people better calibrated in this task. It is argued that the concept of calibration is not wholly appropriate to describe the obtained deviations from the normatively correct responses. This is illustrated by a discriminant analysis performed on the signed deviation scores, which resulted in an almost perfect separation of the three groups, although they were overlapping with respect to calibration.     

Slow brain potentials in the CNV-paradigm

Slow brain potentials were recorded during the foreperiod of a reaction time task, and the effects of instructions governing the trade-off between speed and accuracy were investigated. One brain potential, a slow negative shift preceding S₂, was largely attenuated under accuracy instructions. It is suggested that this shift is dependent on a motor response and that its amplitude reflects the level of motor preparation. Two other brain potentials, a slow positive and a slow negative wave, seem to depend on the psychological properties of S₁. Enhanced amplitudes were found, when S₁ provides information, besides its warning function.     

Postdecisional preference for decision-relevant information as a function of the competence of its source and the degree of familiarity with this information

Three experiments are reported concerning the determinants of postdecisional preferences for decision-relevant information. Two factors were considered: the competence of the source of the information and the degree of prior familiarity with the contents of the information. The first two experiments showed that the competence of the source of decision-supporting information affected the desirability of reading both types of information, whereas the competence of the source of decision-opposing information had very little effect on the desirability of reading either type. In the third experiment, the effects of giving subjects access to prior information supporting or opposing their view on their preferences for further information were investigated under conditions in which the number of choices of this later information were either limited or unlimited. The effects of prior information on choices of decision-supporting information were identical regardless of whether the total amount of information available was limited or unlimited: Less decision-supporting information was chosen when subjects had previously been exposed to decision-supporting information than when they had not, and this difference was greater when they had not previously been exposed to decision-opposing information. However, the choices of decision-opposing information under unlimited choice conditions increased with the amount of decision-supporting information previously read, but decreased with the amount of decision-opposing information previously read. The processes that underlie the choices of information under conditions in which several types are available are discussed.     

Towards a model of stress and human performance

An outline is presented of a model that aims to relate energetical and structural mechanisms of human information processing and to incorporate an interactionally defined stress notion in performance research. The first section summarizes objections to unidimensional notions of arousal and stress. It is concluded that further progress requires the analysis of joint cognitive-energetical processing structures. In the second section two current performance models - in terms of linear stages and resources - are briefly reviewed. Despite a number of problems and objections, it is decided to base the model upon linear stage notions of information processing. This is further elaborated in the third section. In accord with Pribram and McGuinness (1975) three energetical supply systems are proposed which are selectively related to specific cognitive processing mechanisms. Stress is defined as a state of imbalance in the energetical supply which is difficult to restore or to compensate. The final section is devoted to the discussion of some lines of evidence and to suggestions for future research.     

Atomic imaging of the interface between M23C6-type carbide and matrix in a long-term ageing polycrystalline Ni-based superalloy

Besides the well-known cube-on-cube orientation relationship (OR) between M₂₃C₆ carbide and matrix, we have determined a new OR named as the twin-related OR in a long-term ageing Ni-based superalloy on the basis of the extensive and detailed electron diffraction analyses. Furthermore, by means of atomic-resolution high angle annular dark-field imaging technique which is implemented in the aberration-corrected scanning transmission electron microscope, we elucidated the interfacial characteristics between M₂₃C₆ and matrix for above two types of ORs. Taking into account of the interfacial characteristics, we propose that the twin-related OR possesses a higher total interfacial energy. Thus, its frequency of occurrence is lower than that of the cube-on-cube OR though both ORs are usually seen in the long-term ageing samples.     

Matrix differential calculus with applications to simple,hadamard, and kronecker products

Several definitions are in use for the derivative of an m × p matrix function F(X) with respect to its n × q matrix argument X. We argue that only one of these definitions is a viable one, and that to study smooth maps from the space of n × q matrices to the space of m × p matrices it is often more convenient to study the map from nq-space to mp-space. Also, several procedures exist for a calculus of functions of matrices. It is argued that the procedure based on differentials is superior to other methods of differentiation, and leads inter alia to a satisfactory chain rule for matrix functions.     

The effect of negative feedback about oneself and cost of information on preferences for information about the source of this feedback

The present paper reports an experiment in which different amounts of negative self-discrepant information were induced and its effects on information seeking were tested. In addition, the monetary cost of the information available was manipulated. Subjects received fictitious intelligence test results that were negatively discrepant from their self-evaluation. They were then given the opportunity to choose among several articles containing information that either derogated intelligence tests (test-disparaging information) or argued for their validity (test-supporting information). The relative preference for test-disparaging over test-supporting information increased with feedback discrepancy up to a point, but then decreased as this discrepancy became more extreme. The relative preference in reading desirability for test-disparaging over test-supporting articles was also higher when the information cost money than when it did not. In addition, the difference between the desire for the two types of information was greater under cost than under no cost conditions, particularly at the extreme levels of feedback discrepancy.     

Conceptual system and personality: A multivariate study of system stage and personality correlates

Conceptual system as a cognitive-developmental variable in personality has been assumed to relate to different cognitions of self and others and of interpersonal relations at each developmental stage. The assumed relationship between conceptual system and some personality variables was studied in a group of students (N = 85). The “This-I-Believe” test (TIB) [Harvey, O. J. System structure, adaptability and creativity. In O. J. Harvey (Ed.), Experience, structure, and adaptability. New York: Springer, 1966.] for assessing the developmental stage of the conceptual system was administered together with personality scales for traits assumed important in socialization. A modified TIB scoring procedure was used. Highly significant differences in personality were obtained by a MANOVA, using conceptual system for classification. One dimension accounted for discrimination. Measures assumed to relate to sensitivity for and conformity to a social environment contributed most to the discrimination.