Minimal Reaction Time Research Articles

Optimal policies for batch, chain addition polymerizations

The Maximum Principle was applied to determine temperature and initiator addition policies that minimize reaction times for chain addition polymerizations in batch reactors. The gel effect was considered. The optimal policies were found to be a rising temperature and a constant initiator concentration such that k eff for monomer conversion is constant. Under a strong “dead end” effect, the optimal policy results in a significant reduction in the polymerization reaction time. Numerical examples for the polymerization of styrene and methyl methacrylate are presented.

BEHAVIORAL DEFINITION OF MINIMAL REACTION TIME IN MONKEYS1

Two monkeys (Macaca mulatta) were trained to press a key after onset of a tone and to release it after a 1-sec fixed foreperiod terminated by a light. The effects of imposing temporal contingencies on key release reaction times were determined by reinforcing only those releases whose latencies from the light fell within a "payoff band", two time limits 50 msec apart located at some delay following the light. Over several days this delay was first gradually decreased, shortening the interval between light and payoff band, and then gradually increased again. For each delay, the median reaction time and a measure of variability were obtained from the latency distribution. For both animals, median latency could be decreased to 180 msec with the variability remaining small. Moving the payoff band still closer to the light resulted in further decrease in median latency but an abrupt increase in variability. This is in agreement with a model for simple reaction time derived from human research which suggests that this increased variability results from the inclusion of high-variability foreperiod time estimations in the latency distribution. These results indicate that interpretation of monkey response latencies as "minimal reaction times" requires examination of temporal reinforcement contingencies and variability of latencies.

THE RESPONSE TO LIGHT IN ICHTHYOPHIS (AMPHIBIA‐APODA) FROM CEYLON

SUMMARY Specimens of the virtually blind apodan, Ichthyophis glutinosus, have been exposed to general and local illumination, their sensitivity to light confirmed, and the character and timing of the resulting movements analysed. To general illumination the animal usually gives a general stirring and locomotory resopnse after a considerable and variable delay. In some animals this general response is preceded by a shock reflex, the twitch response, the reaction times of which are reasonably consistent and show the intensity/duration relationships discovered by Hecht in automatic light reflexes in Ciona and other animals. The twitch resopnse gives an estimate of the minimal reaction time and shows that the long delay and variability in the timing of the general locomotory movements are due to central processes which determine the response to light in accordance with the general condition and activity of the animal at the time. Ichthyophis is sensitive to light falling anywhere on the head, and on the tail from above. The rest of the body is only slightly sensitive. Local illunination on the head or tail gives rise usually to the general locomotory response, but with caudal illumination a local reflex with a very short reaction time precedes the general response. Judged both from reaction times and from numbers of responses obtained, the tail seems to be more sensitive to light than the head. Operations showed that for a general response to develop from caudal illumination, the spinal cord must be intact, but the local tail reflex is not affected by spinal section. The response of the head to light was not affected by severing the optic nerves. The time relations, sensitivity, general character and spatial distribution of the dermal light sense of Ichthyophis are discussed in relation to the mode of life of the animal and it is concluded that in all respects, its properties coincide very remarkably with the animal's needs.