Search

Three behavioral options were available to food-deprived pigeons: (1) pecking one key resulted in food reinforcement according to a 50-response progressive-ratio schedule, (2) pecking a second key reset the progressive-ratio schedule to the initial progressive-ratio step, and (3) pecking a third key produced a 3-min timeout period. Pecks on the reset key were shocked. Under low and intermediate shock intensities, timeouts were not produced; under high shock levels, timeouts were produced regularly. Timeouts occurred during the initial period of a progressive-ratio step and were more frequent during the longer steps of the progressive-ratio schedule. Response-produced timeouts under these experimental conditions could be interpreted either as an escape from aversive behavioral options or as a low-probability behavior emerging when the food reinforcement schedule exerted weaker control.

A progressive-ratio reinforcement schedule, in which successive reinforcements required an additional 50 responses, was programmed on one key. A response on a second key reset the progressive-ratio schedule to the first step. Before punishment, all pigeons consistently reset the schedule after reinforcement on the first step, thereby minimizing the number of responses required for reinforcement. Punishment was a brief electric shock contingent upon each response on the reset key. The first effect of punishment was to change the frequency of extra responses on the reset key. Under higher intensities of punishment, the pigeons completed the advanced steps of the progressive-ratio schedule before resetting to the first step. Completions of advanced steps were accompanied by decreases in the overall rate of responding and the rate of reinforcement. When the punishment contingency was removed, the major features of pre-punishment performance were recovered.

t but Mendeleev did personally present a second discussion the following 23 August at a meeting of the Society and again on 3 December.2 In the meantime a foreign correspondent in St. Petersburg, V. von Richter, published a brief notice on Mendeleev's proposal in the 17 October 1869 issue of the Zeitschriftfar Chemie3 and again in December,4 and an extended German summary in the same year gave Mendeleev's tabulation, reset in German type.5 It was the latter article that caught the attention of the chemist Lothar Meyer and prompted immediate publication of his own similar studies,6 which in turn ignited such worldwide polemics among the numerous workers within the same stream that 1869 remains very clearly marked, historically at least, as the year of the launching of the new concept. This historical landmark became further highlighted a few years later by a dramatic inci* Baltimore, Maryland. The author acknow

In an attempt to develop techniques which might lead to quantitative measures of human conflict behavior, female college students were placed in a free operant situation where responding was concurrently reinforced (with money represented by counter tally) and punished (with electric shock) with increasing severity for successive responses. Ss were able to reset the shock to a low level by making a second response, which resulted in subtraction of counter tallies. Results indicate that as shock intensity increases, total responding decreases, and the average number of responses before reset also decreases. Variations in the magnitude of positive reinforcement failed to have any effects. Several factors which might have been involved were discussed. Suggestions were made for clarifying the role that duration of exposure to shock plays in the situation.

Each of three pigeons was studied first under a standard fixed-interval schedule. With the fixed interval held constant, the schedule was changed to a second-order schedule in which the response unit was the behavior on a small fixed-ratio schedule (first a fixed-ratio 10 and then a fixed-ratio 20 schedule). That is, every completion of the fixed-ratio schedule produced a 0.7-sec darkening of the key and reset the response count to zero for the next ratio. The first fixed-ratio completed after the fixed-interval schedule elapsed produced the 0.7-sec blackout followed immediately by food. These manipulations were carried out under two different fixed-interval durations for each bird ranging from 3 min to 12 min. The standard fixed-interval schedules produced the typical pause after reinforcement followed by responding at a moderate rate until the next reinforcement. The second-order schedules also engendered a pause after reinforcement, but responding occurred in bursts separated by brief pauses after each blackout. For a particular fixed-interval duration, post-reinforcement pauses increased slightly as the number of pecks in the response unit increased despite large differences in the rate and pattern of key pecking. Post-reinforcement pause increased with the fixed-interval duration under all response units. These data confirm that the allocation of time between pausing and responding is relatively independent of the rate and topography of responding after the pause.

Lever responses of rats were reinforced under progressive ratio schedules where the response requirement increased after each reinforcement. The ratio could be reset to its initial value by an alternative response. Systematic relations were found between the size of the progressive ratio schedule and the frequency of the reset responses. The procedure facilitated an analysis of the interaction of effort and time variables which were reflected in the sequential properties of the responses.

Two chimpanzees were required to choose between a fixed-ratio schedule and a progressive-ratio schedule which increased in response requirement by 20 responses each time it was chosen. Each choice of the fixed ratio reset the progressive ratio to its minimum value. The fixed-ratio requirement was varied from 40 to 1000 responses. The subjects' preferences for the progressive-ratio schedule varied as a function of the magnitude of the fixed-ratio requirement. An analysis of the preference data indicated that the animals tended to minimize reinforcement cost rather than match the progressive-ratio requirement to the fixed-ratio requirement. In a second experiment, selection of the fixed ratio did not reset the progressive-ratio requirement to its minimum value. In this case, the animals matched the progressive-ratio requirement to the fixed-ratio requirement. A model based on reinforcement cost is presented which permits accurate prediction of preferences between fixed and progressively increasing ratio schedules.

Publisher Summary This chapter discusses permutation-reset semi-automata. An input in a semiautomaton which permutes its states is called a permutation input. Various theorems are proven in the chapter. Permutation, reset semi-automata, and covering of reset semiautomata are discussed. Every reset semiautomaton can be covered by a direct product of two-state reset semiautomata. The chapter discusses grouplike semi-automata, and covering of grouplike semi-automata. A grouplike semiautomaton can be covered by a cascade product of simple grouplike semiautomata—that is, ones which correspond to simple groups. Every semiautomaton A can be covered by direct and cascade products of semiautomata of two kinds: (1) simple groupUke semiautomata, and (2) two-state reset semiautomata.

The Teaching of Chemistry By N. F. Newbury. Second edition, completely revised and reset. Pp. xv + 294. (London: William Heinemann, Ltd., 1958.) 21s. net.

Gas Calorimetry The Determination of the Calorific Value of Gaseous Fuels. By C. G. Hyde and M. W. Jones. Second edition, entirely revised and reset. Pp. vii + 456. (London: Ernest Benn, Ltd., 1960.) 105s. net.

CHAMBERS first published a volume of mathematical tables in 1844. This was enlarged and reset in 1878, and has been re-issued at intervals in the same format. The volume will be, familiar to most people who have, at some time or other, needed to use 7-figure tables. It is now replaced by the volumes under review. They are in no sense a revision, but rather an entirely new publication. For good reasons given in the preface, six-figure values are given in the new tables instead of seven. Chambers's Six-Figure Mathematical Tables By Dr. L. J. Comrie Vol. 1: Logarithmic Values. Pp. xxii+576, Vol. 2: Natural Values. Pp. xxxvi + 576. (Edinburgh and London: W. and R. Chambers, Ltd., 1948–1949.) 42s. net each.

THE adequate control of temperature is of fundamental importance in nearly all branches of science, and there are numerous applications in industrial and technical fields. Courses of study and text-books for students of physics, chemistry, engineering and metallurgy, invariably include, in the heat section, a discussion of the methods of temperature measurement ; but, in general, the treatment is too brief and inadequate. The practical difficulties inherent in all thermal measurements are very rarely appreciated, and insufficient regard is paid to the necessity of a correct choice of instrument and method for the temperature or temperature-difference measurement. Methods of Measuring Temperature By Dr. Ezer Griffiths. Third edition, revised and reset. Pp. x + 223. (London: Charles Griffin and Co., Ltd., 1947.) 20s. net.

n/a

Life of the Shore and Shallow Sea By Dr. Douglas P. Wilson. Second edition, completely revised and reset. Pp. xvii + 213 + 45 plates. (London: Nicholson and Watson, Ltd., 1951.) 15s. net.

R C Weast (Ed) Oxford: Blackwell Scientific 1969 pp xxiv + 2033 price £12 10s This is such a well known book that it needs no introduction which spells out its aims. Although some tables are still out of date, revisions are continuously being made and, in this edition, the table of isotopes (296 pp) and that of physical constants of organic compounds (468 pp) have been reset and updated.

By Herbert Bristol Dwight New York. London: The Macmillan Company. Pp. x + 336. Price 26s. A deservedly popular work of reference, first published almost thirty years ago, this book now appears in a fourth edition, re-designed and reset. The section on definite integrals has been considerably enlarged and a section added on integrals essentially of elliptic type.

Reading French's Differential Diagnosis has been a new experience for me. I was not sure how one should go about such a task; it is not my habit to read encyclopedias. My first attempt was to try to use the volume by asking a question and looking for the answer. This turned out to be unsatisfactory because my questions usually hinged upon etiology and French's is a volume dealing mainly with manifestations. The only recourse, then, was the simple one of starting at the beginning. If every page was not read, each was fingered. The format can be dispensed with as displaying the expected British excellence of composition. This edition has 1,034 pages compared to 1,111 pages in the previous one. This is because the present volume has been entirely reset and the use of double columns to the page greatly improves readability. There are now 812 illustrations compared

The Teaching of Science in Secondary Schools Compiled by a Joint Committee of the Incorporated Association of Assistant Masters and the Science Masters' Association. Second edition, revised and reset. Pp. ix + 274. (London: John Murray (Publishers), Ltd., 1958.) 17s. 6d. net.