Information underload: Recognition of slowly-presented alphabetic characters

The accuracy of identification of alphabetic letters was examined under three experimental procedures: slowly plotting all of the dots associated with a given display of letters in their correct spatial positions, but in a random temporal order; rapidly plotting one half of the dots associated with a display, and after a variable delay, rapidly plotting the other half of the dots; and rapidly plotting only a fraction of the total number of dots associated with the display. The accuracy of identification suffers as the rate of plotting is decreased and as the interval between the successive fields is increased. Therefore, a failure of spatial-temporal integration is inferred. The results of the separate procedures are partially consistent with an interpretation of a discrete, non-synchronized perceptual moment of 120–150 msec duration, assuming no accumulation of information across successive moments.     

Bias functions and operating characteristics of rats discriminating auditory stimuli

Rats were trained to discriminate between two bursts of random noise that differed in intensity. In a two-lever, discrete-trial procedure, correct responses were reinforced with brain stimulation, and incorrect responses produced timeout. Responding was studied as a function of the decibel difference between the stimuli, the probabilities of presenting the stimuli, the relative duration of timeout consequent upon the two types of incorrect responses, and the absolute duration of timeout consequent upon incorrect responses. The results showed that the distribution of responses between the two levers depended upon the stimulus probabilities, but were independent of either the absolute or relative durations of timeout. When the stimulus probabilities were varied, the response probabilities did not match the stimulus probabilities; when the relative durations of timeout were varied, the animals did not obtain the maximum rate of reinforcement per unit time. Instead, the animals distributed their responses so as to obtain the maximum number of reinforcements at each level of discrimination. In addition, the level of discrimination increased as a function of the decibel difference between the stimuli.     

A method for clustering eigenvalues

A method of computing communalities is presented which attempts to cluster eigenvalues about zero. Results are exhibited which show reduction of rank using computed communalities.This paper is based on work performed under Contract AF 30(602)-3300 monitored for the U. S. Air Force by Mr. Rocco Iuorno, Rome Air Development Center. The use, under the above contract, of the IBM 7094 computer located at Aeronautical Systems Division, Wright-Patterson Air Force Base, is gratefully acknowledged. Permission is granted for reproduction, translation, publication, use, and disposal in whole and in part by or for the United States Government.     

Evaluation of a preventive intervention for a self-selected subpopulation of children

Evaluated an experimental preventive intervention developed for children who perceived their parents as problem drinkers. The 8-session program was designed to improve children's coping, self-esteem, and social competence, and modify alcohol expectancies which were specified as mediators of the effects of parental alcohol abuse on child mental health. Participants were 271 self-selected 4th-, 5th-, and 6th-grade students in 13 schools. The children were randomly assigned to treatment or delayed treatment conditions and the program was given to three successive cohorts of students. A meta-analysis across three different cohorts indicated significant program effects to improve knowledge of the program content and the use of support- and emotion-focused coping behaviors for the full sample. A slightly stronger range of effects was found for a high-risk subsample. This research was funded by the National Institute of Mental Health Grant P50-MH39246 to support a Preventive Intervention Research Center and Prevention Training Grant T32-MH18387-02.     

Differential thresholds for limb movement measured using adaptive techniques.

Differential thresholds for limb movement were measured in 10 subjects, using the transformed up-down procedure. Subjects were required to indicate which of two random displacement perturbations delivered to their forearms had the larger standard deviation (SD). The SD of the reference signal was fixed for each experimental condition at one of seven values ranging from 0.05 to 3.2 mm. THe SD of the other signal varied depending on the subject's response. Using this procedure, the differential threshold for limb movement was calculated to be 8%, which is very similar to the thresholds estimated previously for changes in limb position (9%) and force (7%). The sensitivity of the human proprioceptive system to changes in limb displacement was much greater than anticipated, with subjects being able to resolve a 5-microns difference between two perturbations delivered to their arms.     

A Behavior Analytic Interpretation of the Therapeutic Relationship

The paper examines, from a behavior analytic perspective, the mechanisms through which change occurs within the context of the therapeutic relationship in individual psychotherapy. The analysis focuses upon the therapist’s shaping of the client’s behavior through subtle nonverbal cues and explicit verbal analyses. In the relationship, therapists modify behavior that has created difficulties for the client in the natural environment, and clinical change is dependent upon the extent to which those in the natural environment will reinforce functionally similar response classes. Ferster’s distinction between natural and arbitrary reinforcement and Skinner’s distinction between contingency-shaped and rule-governed behavior are also used to describe the manner through which change occurs. The goal of the paper is to stimulate behavior therapists to look more closely at the therapeutic relationship as a mechanism of clinical change and to help those of other perspectives see how their effectiveness within the relationship can be understood using the principles of learning.

     

Locus of control and self-esteem as moderators of stressor-symptom relations in children and adolescents

Locus of control and self-esteem were examined as moderators of links between negative life events and psychological symptoms in 238 young people 8 to 16 years old. Results indicated that locus of control buffered the effects of stressors on psychological symptoms, and the pattern of buffering did not differ by age or gender. Self-esteem buffered the link between Stressors and symptoms, but only for girls. Further analyses with girls only revealed a conjunctive moderation effect of locus of control and self-esteem: When faced with many negative life events, girls who have both an external locus of control and low esteem show the highest psychological maladjustment.The writing of this article was supported by National Institute of Mental Health Training grant 5 T 32 MH18387-03 in Child Mental Health/Primary Prevention.