Real-time clocks for microcomputers in behavioral research

Real-time clock strategies are described for microcomputers in behavioral research. Software-oriented and hardware-oriented counters are described in both free-running and strobed modes. An example of a clock using the Intel 8253 is given, along with driving software in 8080 assembly code and hardware for the S-100 bus.     

Parental Visitation of the Institutionalized Retarded

An inverse relationship was found between the number of parental visits an institutionalized retarded child received and the distance of the parental home from the institution. When the natural parents were living together, the retarded child was shown to receive more visits than when the child's parents were separated or one parent was deceased. Single mothers were found to be living significantly closer to the facility than single fathers. Single fathers appeared to put more effort into visiting, since they visited just as often as the mothers, but had to travel further distances than the mothers to do so. Visitation frequency followed a curvilinear pattern, decreasing uniformly from 20–60 miles (from 0–20 miles visitation frequency is uniform), and then leveling off.     

Temporal properties of responding during stimuli that precede response-independent food

Pigeons' keypecks were reinforced with grain on the average of once per minute by schedules that maintained low response rates and by schedules that maintained high response rates. During these schedules, a fixed-duration conditioned stimulus (CS) ranging from 7.5 to 120 sec in duration across conditions terminated with response-independent food. Response rates during the CS were inversely related to CS duration. The rates and the temporal patterns of responding during the shortest CS were similar whether the ongoing schedule maintained high response rates or low response rates. As CS duration increased, the rate and pattern of responding during the CS converged on the rate and pattern of responding maintained by the baseline schedule. These data indicate that changes in responding during stimuli that signal response-independent reinforcement are not homogeneous throughout the CS; that response measures, such as “suppression ratios”, which presume homogeneity may mislead us; and that conditioned suppression and conditioned enhancement may be better talked about in terms of species-specific approach and avoidance than in terms of emotional states.