One-session cognitive treatment of dental phobia: preparing dental phobics for treatment by restructuring negative cognitions

The purpose of this study was to investigate the effectiveness of a single session of cognitive restructuring in a sample of phobic dental patients. Fifty-two patients were randomly assigned to one of three conditions: cognitive restructuring (modification of negative cognitions), provision of information (about oral health and dental treatment), and a waiting list control condition. Both interventions maximally lasted one hour. In comparison with the waiting list control condition and the information intervention condition, the cognitive intervention condition not only showed a large decrease in frequency and believability of negative cognitions, but also exhibited a clear decline in dental trait anxiety. Analysis at a follow-up of one year demonstrated a further, drastic reduction in dental anxiety in both intervention conditions, wherein the difference among these conditions was not maintained. It is concluded that it is possible to obtain substantial reductions of dental trait anxiety through a single session of cognitive restructuring. Nevertheless, repeated exposure to the dental situation seems necessary for a further reduction of anxiety.     

The relationship between locus of control and long-term stuttering treatment outcome in adult stutterers

The present study was designed to investigate the extent to which adult stutterers' scores on the Locus of Control of Behaviour (LCB) scale are predictive of their ability to maintain speech fluency immediately following intensive treatment and approximately 2 years later. Twenty-one subjects participated in a 3-week intensive treatment program based on the Precision Fluency Shaping Program. Thirteen subjects could be contacted again 2 years later to participate in a follow-up evaluation. While most subjects showed a significant long-term improvement in fluency, no predictive relationship was found between scores on the LCB scale and the level of fluency, measured in percentage of words stuttered, post-treatment or at follow-up. However, LCB scores were found to be predictive of the subjects' fluency self-evaluation measured post-treatment and at follow-up. Overall, the present study suggests that while the LCB scale may contribute to the prediction of long-term treatment outcome, particularly as perceived by the client, other client and process variables will need to be considered as well.     

Perceptual scaling of synthesized musical timbres: Common dimensions,specificities, and latent subject classes

To study the perceptual structure of musical timbre and the effects of musical training, timbral dissimilarities of synthesized instrument sounds were rated by professional musicians, amateur musicians, and nonmusicians. The data were analyzed with an extended version of the multidimensional scaling algorithm CLASCAL (Winsberg & De Soete, 1993), which estimates the number of latent classes of subjects, the coordinates of each timbre on common Euclidean dimensions, a specificity value of unique attributes for each timbre, and a separate weight for each latent class on each of the common dimensions and the set of specificities. Five latent classes were found for a three-dimensional spatial model with specificities. Common dimensions were quantified psychophysically in terms of log-rise time, spectral centroid, and degree of spectral variation. The results further suggest that musical timbres possess specific attributes not accounted for by these shared perceptual dimensions. Weight patterns indicate that perceptual salience of dimensions and specificities varied across classes. A comparison of class structure with biographical factors associated with degree of musical training and activity was not clearly related to the class structure, though musicians gave more precise and coherent judgments than did nonmusicians or amateurs. The model with latent classes and specificities gave a better fit to the data and made the acoustic correlates of the common dimensions more interpretable.     

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.     

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.     

Field dependence and the effect of REM deprivation on thirst.

Recently a number of studies have concerned the possible function of rapid eye movement (REM) sleep and the mastery of stress. The present study was designed to explore the possibility that REM sleep might play a function in reducing the potency of a stressful physiological stimulus, thirst, as well as the possibility that such a function might be specific to individuals falling at different points along the field-dependence dimension. While there was no difference between REM deprivation and non-REM awakening nights in subsequent morning thirst, there was a significant interaction between field dependence and night on morning thirst measures for 10 college students. These results are discussed in light of previous work on stylistic differences in dreaming and their possible role in adaptation to stress.     

The integration of motivational information: A conjoint measurement analysis

Within Anderson's (1974a, b, c, 1978b) information integration theory, the integration of motivational information was investigated by means of conjoint measurement techniques. Eighteen university students were asked to judge hypothetical co-students characterized by three features (intelligence, motivation and the extent to which they study) according to their chances to pass. Both rank order data and ratings were obtained. The orderings of most subjects could be represented very well by an additive model. A polynomial regression procedure was applied to determine the shape of the response function for the ratings. As this function was quite linear for all subjects, the ratings could be said to form an interval scale.     

Concurrent avoidance of shocks by pigeons pecking a key

Three pigeons were studied on concurrent, unsignaled, avoidance schedules in a two-key procedure. Shock-shock intervals were two seconds in both schedules. The response-shock interval on one key was always 22 seconds, while the response-shock interval associated with the other key was varied from 7 to 52 seconds in different experimental conditions. Response rates on the key associated with the varied schedule tended to decrease when the response-shock interval length was increased. Responding on the key associated with the constant schedule was not systematically affected.