A real-time satellite system based on UNIX

One solution to the difficulty of running real-time applications under UNIX is to develop the application programs on an available UNIX system and execute them on a dedicated satellite processor. This combines the advantages of a powerful timesharing operating system with the real-time capabilities of a single-process system. PARASITE, a real-time satellite system, provides tools for developing the application program on the host and executing it on a satellite. A host utility serves to invoke the standard UNIX C compiler and link its output with the PARASITE library. The PARASITE library consists of routines that mimic the standard library and routines that read and write the real-time peripherals. PARASITE currently supports digital inputs and outputs, asynchronous serial-line interfaces, program-mable real-time clocks, and analog-to-digital and digital-to-analog converters. Another PARA-SITE utility downloads the object code of the user program and PARASITE support code into the satellite, where it runs independently. Once the application routine is executing on the satellite, it controls the satellite processor at all times and is continuously available for servicing hardware-generated interrupts. When a real-time peripheral interrupt routine is invoked by a hardware interrupt, it sends a software signal to the user program, in addition to processing the interrupt. This allows the user program to perform additional tasks that are specific to the application. All data to be permanently stored must be transferred to the host. Since the satellite has no direct access to the resources of the host, a process running on the host receives the data and manages files. PARASITE provides packet driver routines on both the host and the satellite, which together handle the data transmission protocol.     

Validity of teacher nominations of child behavior problems

The purpose of this study was to examine the validity of teachers' identification of problem children. Ninety-five third-grade children served as subjects. Teachers nominated children as a conduct problem, withdrawal problem, or normal, resulting in 16, 14, and 65 children being assigned to the three groups. Behavioral observations, peer sociometric ratings, and academic achievement scores were collected. The results indicated that conduct problem children differed from normal children on behavioral, sociometric, and academic measures, whereas withdrawn children differed from normals on the latter two measures. Conduct problem and withdrawal problem children did not differ on any of the dependent measures. The results suggest that teachers can identify children who are having difficulties in class but may be less accurate in differentiating between different types of problem children.This research was supported in part by NIMH grant MH-28859-01. Data reported in this article are part of a larger project assessing the social skills of children.     

Contextual potentiation of acquired behavior after devaluing direct context-US associations

In two experiments, water-deprived rats were exposed to tone-footshock pairings in a particular conditioning context. In Experiment 1, the training parameters were selected on the basis of parametric pilot data so as not to produce direct associations between the conditioning context and footshock. Despite independent evidence of no appreciable direct association between the conditioning context and footshock, animals tested in the conditioning context exhibited more lick suppression to the tone than other animals tested with the tone outside of the conditioning context. Thus, the conditioning context potentiated suppression to the tone in the absence of appreciable fear of the conditioning context. In Experiment 2, training parameters were used that permitted the formation of direct associations between the conditioning context and footshock; however, for half the animals, these associations to the context were then extinguished. With the tone absent, a comparison of extinguished animals tested either in the conditioning context or outside the conditioning context detected no differences in suppression, demonstrating the effectiveness of the extinction manipulation. However, other animals also subjected to extinction of direct context-footshock associations displayed greater suppression to the tone within the conditioning context than comparable animals tested outside the context. Collectively the data indicate that the superior retention-test performance seen within the training context can arise both from the commonly assumed direct associations between the training context and the unconditioned stimulus and from the potentiation by the training context of the associations between the nominal conditioned stimulus and unconditioned stimulus.     

Choice reaction time with a random foreperiod

Choice reaction latencies were measured at three different a priori probabilities for two stimulus alternatives. Unlike the results of some other studies, the mean latency of a given response was nearly the same whether the response was correct or incorrect. The discriminable stimuli were a 1000- or a 1700-Hz tone presented at 70 dB SPL. Latencies and standard deviations, based on about 17,000 observations, are reported for three observers. The data are compared with predictions of the optimum sequential model of Wald and Stone and two modifications of that random-walk model, one proposed by Link and Heath and the other proposed by Laming. Fast-guess analyses were also carried out. The three-parameter version of either the sequential or the modified random-walk models provided reasonably accurate predictions of the mean data for each observer. The parameters estimated by the fast-guess analysis were unrealistic. There are three obvious differences between this experiment and most previous choice reaction-time experiments. First is stimulus modality#x2014;we used an auditory signal, whereas most of the previous studies used a visual signal. Second, the observers practiced more in this experiment than in most previous experiments. Finally, there was a random foreperiod with a heavy penalty for anticipations. One or more of these factors is the probable reason for the discrepancy between our results and those of previous studies.     

A COMPREHENSIVE EVALUATION OF REINFORCER IDENTIFICATION PROCESSES FOR PERSONS WITH PROFOUND MULTIPLE HANDICAPS

We evaluated comprehensively a preference assessment for identifying reinforcers for persons with profound multiple handicaps. Four experiments were conducted involving 18 individuals. Results of Experiment 1 replicated previous findings in that the assessment identified student preferences for respective stimuli, and caregiver opinion of preferences did not coincide with the systematic assessment. Results of Experiment 2 indicated highly preferred stimuli were likely to function as reinforcers in training programs, whereas stimuli not highly preferred did not function as reinforcers. Results of Experiment 3 suggested the 12 stimuli used in the assessment represented a comprehensive stimulus set for identifying preferences, although the utility of the set sometimes could be enhanced by caregiver opinion. Results of Experiment 4 indicated the assessment identified preferences likely to be maintained over time. Overall, results are discussed in terms of identifying limits and alternatives to a behavioral teaching technology when applied to persons with profound multiple handicaps.     

Economic substitutability of electrical brain stimulation, food, and water.

Concurrent variable-ratio schedules of electrical brain stimulation, food, and water were paired in various combinations as reinforcement of rats' lever presses. Relative prices of the concurrent reinforcers were varied by changing the ratio of the response requirements on the two levers. Economic substitutability, measured by the sensitivity of response ratio to changes in relative price, was highest with brain stimulation reinforcement of presses on both levers and lowest with food reinforcement of presses on one lever and water reinforcement of presses on the other. Substitutability with brain stimulation reinforcement of presses on one lever and either food or water reinforcement for presses on the other was about as high as with brain stimulation for presses on both levers. Electrical brain stimulation for rats may thus serve as an economic substitute for two reinforcers, neither of which is substitutable for the other.     

Decreasing junk-food consumption through the use of self-management procedures: a case study

By using a self-management program, a 25-yr.-old white male was able to decrease the amount of junk food and beverage consumed while increasing the amount of healthier food and beverage ingested during evening snacks. This change was evident at 6 wk. and at a 6-mo. follow-up. Factors contributing to this success were discussed.     

Integral processing of visual place and auditory voicing information during phonetic perception.

Results of auditory speech experiments show that reaction times (RTs) for place classification in a test condition in which stimuli vary along the dimensions of both place and voicing are longer than RTs in a control condition in which stimuli vary only in place. Similar results are obtained when subjects are asked to classify the stimuli along the voicing dimension. By taking advantage of the "McGurk" effect (McGurk & MacDonald, 1976), the present study investigated whether a similar pattern of interference extends to situations in which variation along the place dimension occurs in the visual modality. The results showed that RTs for classifying phonetic features in the test condition were significantly longer than in the control condition for the place and voicing dimensions. These results indicate a mutual and symmetric interference exists in the classification of the two dimensions, even when the variation along the dimensions occurs in separate modalities.     

Interpersonal problem solving: An intervention program for preschool children

The purpose of the present study was to evaluate the effectiveness of an intervention program designed to train preschool children in interpersonal problem solving skills. Forty preschool age children were randomly assigned to an experimental or control group. Experimental subjects were trained in interpersonal problem solving skills for ten weeks, four days per week, for a total of 10–13 hours. Problem-solving skills were assessed at pretest, posttest, and three months after training was completed. Seventy-eight percent of the children who participated in pretest and posttest were tested at follow-up. Results indicated that the experimental group, compared to the control group, showed a significant increase in both cognitive—verbal and behavioral interpersonal problem-solving skills from pretest to posttest and that these changes were maintained at follow-up testing. Discussion focuses on suggestions for future research and implications for applied settings.