Requirements for minicomputer operating systems for human experimentation and an implementation on a 4K PDP-8 computer

A programming system is described which considerably simplifies preparation and running of experiments on PDP-8 computers.     

The effect of perceived distance on induced movement

The magnitude of induced movement was measured as a function of the perceived depth between the test object and the plane of the induction object, with this perceived depth produced by stereoscopic cues. Three experiments were conducted. In each experiment, the induction object (a frame of constant physical size) was positioned at one of three distances with the test object (a point of light) placed successively at each of the three distances. Predictions of the magnitude of induction as a function of the depth separation of the test and induction object were made from the subject-relative and object-relative hypotheses of induced motion. It was expected, however, that neither of these hypotheses would predict the results independently of a factor described in the adjacency principle. This principle states that the effectiveness of whatever cues or processes determine the induced movement will decrease with increased depth between the test and induction object. The data indicate that the adjacency principle must be considered in explaining the results. The subject-relative rather than object-relative hypothesis as modified by the adjacency principle was most successful in predicting the results. Control conditions in which the frame was stationary and the point of light was physically moving were also used. Despite the fact that the relative displacement of the objects on the eye in the experimental and control conditions were the same, the results indicate that O could distinguish between these two kinds of conditions. Although the apparent movement was greater in the control conditions than in the experimental conditions, the reverse is true if the total perceived movement of the test and induction object are considered together.     

Prediction of choice reaction time from information of individual stimuli

A model is developed to predict the reaction time to stimuli using information content of the individual stimuli. Review of previous research in the area showed inconsistencies due possibly to the mode of stimulus presentation or to the number of stimuli. Two experiments designed to cover the range of variables used in previous experiments were conducted. The results indicate that the model makes accurate predictions over the entire range of variables used. A comparison to earlier studies also indicates a close correspondence. nt|mis|Acknowledgment is due the Office of Naval Research which supported this research through a prime contract, NOnr 2512(00), with General Dynamics Electric Boat Division as a part of the SUBIC. (SUBmarine Integrated Control) program.     

Orthogonal inter-battery factor analysis

It is the purpose of this paper to present a method of analysis for obtaining (i) inter-battery factors and (ii) battery specific factors for two sets of tests when the complete correlation matrix including communalities is given. In particular, the procedure amounts to constructing an orthogonal transformation such that its application to an orthogonal factor solution of the combined sets of tests results in a factor matrix of a certain desired form. The factors isolated are orthogonal but may be subjected to any suitable final rotation, provided the above classification of factors into (i) and (ii) is preserved. The general coordinate-free solution of the problem is obtained with the help of methods pertaining to the theory of linear spaces. The actual numerical analysis determined by the coordinate-free solution turns out to be a generalization of the formalism of canonical correlation analysis for two sets of variables. A numerical example is provided.This investigation has been supported by the U.S. Office of Naval Research under Contract Nonr-2752(00).     

Reversal learning of object and positional discriminations by mink, ferrets and skunks

Mink, ferrets and skunks were tested on successive reversals of two-choice object or positional discriminations in a modified Wisconsin General Training Apparatus. All species showed considerable improvement in performance after considerable training and some subjects exhibited one-trial reversal learning. Mink and ferrets persistently made more errors when position cues were relevant than when object cues were relevant; the reverse was true of skunks.     

THE ROLE OF RESPONSE DELAY IN IMPROVING THE DISCRIMINATION PERFORMANCE OF AUTISTIC CHILDREN

This study investigated the influence of a response delay requirement on the discrimination performance of autistic children. In the context of a multiple baseline design with subsequent repeated reversals, two conditions were compared: a no-response-delay condition, where the child was allowed to make the target response immediately after presentation of the discriminative stimulus versus a response-delay condition, where the target response was permitted three seconds following the discriminative stimulus when the therapist would signal the child to respond. The results showed that the response-delay condition produced higher levels of correct responding than the no-response-delay condition. In addition, teachers in the research setting rated the response-delay procedure to be a practical and effective teaching technique that could be implemented in a classroom setting. The results were discussed in relation to the literature on impulsivity, and were interpreted as indicating that the response-delay procedure provides a valuable technique for teaching autistic children.     

A solid-state device for eliminating electrical noise and biopotentials in electromyographic (EMG) recordings

A small, low-cost, integrated circuit device is described. This circuit reduces electrical noise, such as that produced from a poor electrode-skin interface and power-line interference (60 Hz). Advantages of this device, with regard to use in electrically noisy environments and with long cables, are discussed.     

Relative cues and absolute distance perception

It is possible, in theory, for the simultaneous occurrence of several different relative cues of distances to increase the veridicality of the perception of absolute distance. To test whether this actually occurs, a three-dimensional display was viewed monocularly while moving the head laterally, under conditions in which some error in perceived absolute distance was expected. The perceived absolute distance of the display was measured with the number of relative cues of distance within the display varied. No systematic reduction was found in the error in perceived absolute distance as a consequence of the variation in the number of relative cues. The study provides no evidence that the potential source of absolute distance information provided by relative cues is utilized by the visual system.     

Transference reactions in conjoint therapy: A view from an observation group

Summary This paper reports on conjoint therapy conducted with the individual therapists of two of the group's members observing the group sessions. The development of the transference reactions of all group members are highlighted and suggestions are made regarding the most useful methods of handling these transference reactions to help create a mutative experience for the members of the group.The author wishes to thank Dr. Judith Isaac for her comments and editorial assistance throughout the preparation of this paper.