Skinner's original description of the effects of fixed-ratio reinforcement schedules in terms of response-rate measures (14) has served as the point of departure for all such subsequent investigations. The two salient aspects of fixedratio performance that have thus far received the most attention are the high response rates toward the end of the inter-reinforcement period and the characteristic pause after the delivery of a reinforcement (1,3,5,8,10,13).Fixed-ratio schedules also have some behavioral effects that are not easily described in terms of response-rate changes. For instance, the internal cohesion of response sequencesmaintainedby ratio reinforcementishigher thanit is for interval reinforcement. The extinction pattern after fixed-ratio reinforcement provides some of the evidence for this property. This pattern is characterized by maximal response rates which are maintained until they give way to an abrupt cessation of responding. If additional responses appear, they appear in bursts, rather than at the intermediate response rates that emerge during extinction after interval reinforcement (14). Further evidence for such cohesion can be seen in Dews' (4) and also in Herrnstein and Morse's (7) pharmacological data, which indicate that be-' havior maintained under ratio schedules is more resistant to disintegration by drug action than is behavior maintained under interval schedules.The concept of "Internal cohesion" of response runs (the term run is used in the sense of sequence) will be defined in terms of the probability that the run will terminate--a definition which is not inconsistent with common usage. Thus, the cohesion of a run would be high when the probability of its termination is low. A systematic investigation of this property of response runs would, therefore, involve a description of runs in terms of their probabilistic structure, i. e., in terms of the probability that the run will terminate at any point. Once a technique is available, the effects of various parameters can be investigated.

Two procedures were used in an investigation of the effects of deprivation upon counting and timing. Under the first procedure, fixed minimum interval (FMI), the rat received liquid reinforcement every time it pressed bar B after having waited a minimum of 5 sec following a press on bar A. Under the second procedure, fixed consecutive number (FCN), reinforcement was delivered every time the rat pressed bar B following a run of at least four consecutive responses on bar A.Water deprivation was varied over a set of values ranging from 4 to 56 hr. Deprivation had almost no effect on the waiting time in the FMI procedure, or on the number of responses per run in the FCN procedure. With both procedures, increasing deprivation shortened the pause between reinforcement and the next response. In the FCN procedure, the speed with which the runs were exectrted increased with increasing deprivation, although the number of responses in these runs was relatively unaffected.

The "revealed operant" is described as a practical research tool. It differs from traditional types of operants that are recorded as single instantaneous events, in that some of the revealed operant's sub-operants can be recorded conveniently, and that the first and last of these are made on separate manipulanda. A revealed operant can be studied by examining multiple measures relating to the internal structure of individual occurrences of the operant, including incomplete occurrences. A practical method for implementing revealed operants for human subjects, using only a personal computer and keyboard, is used in pilot studies of (a) resurgence after extinction and after an abrupt increase in the revealed operant's work requirement, (b) variabil ity changes during and after extinction, (c) effects of fixed ratio size and of the revealed operant's work requirement, (d) sensitivity of different components as a function of their distance from the end of the revealed ope (ant, and (e) changes in the revealed operant's internal patterns as a function of long-term repetition.

One characteristic shared by all behavior experimentation is that stimuli are presented to a subject according to pre-designed rules. These rules are variously called conditioning procedures, behavioral procedures, reinforcement contingencies, or reinforcement schedules. While behavioral investigations may differ widely with regard to the rigor of specification as well as the nature of the stimuli they employ (even the term stimulus is far from universal), the rules or conditions that govern the presentation of these stimuli must always in some way be conveyed in reporting the work. The purpose of this paper is to propose a notation for the description of these rules.In published papers they are most frequently described by circumlocution, a method of communication which may require anywhere from several sentences to several pages of text. depending on the author's style and the complexity of the rules concerned. On occasion, authors dissatisfied with the inelegance and verbosity of this mode of description have also devised special notations suitable for their own particular needs. One drawback of such specialized notations has always been, however, that their usefulness tends to be restricted to the applications for which they were designed. The notation system proposed in the present paper represents an attempt to satisfy a wide-enough range of requirements to make it a reasonable first approximation to a generally useful system for describing the essential features of behavioral procedures by means of symbolic diagrams. It is essentially an amalgam of four other notations that are in current use: (1) the one traditionally used in psychological paradigms to describe the succession of stimuli and responses; (2) the flow-chart notation widely used in electronics, computer programming, and systems engineering; (3) the notation of Boolean algebra, which has found its main applications in set theory and logic; and (4) the notation of mathematics.The history of science bears testimony to the fact that the advent of a good notation can have effects beyond merely expediting communication. The symbolic notation of chemistry, for example, served as a catalyst for the development of theory in providing a framework within which existing knowledge could be systematized. It is possible that in behavioral science a successful notation, whether it be the present one or some other, could play an analogous role in the classification of procedures. By presenting a set of intricate interrelations in a concise and schematic form, a diagrammatic or symbolic notation can often lay bare the essential structural features of these interrelations, thereby facilitating their analysis. Thus, a good notation system could implement the discovery of formal parallels between behavioral procedures, and generally suggest schemes for their classification. DEFINITIONS OF SYMBOLS Stimuli, Responses, and Time IntervalsThe symbols used to designate stimuli, responses, and time intervals are the usual abbreviations S, R, and T, respectively. These s...

In three experiments with college students, the effects of different acquisition procedures on response variability were studied. The computer keypressing task involved learning a sequence with a minimum number of presses on a subset of the keyboard. Procedures differed in type of training and in the number, size, and sequence of training steps. Experiment 1 showed that instructions and shaping in three steps generated less variability in the number of responses made in each keypress sequence than shaping in six steps. Subsequent experiments showed that a large increase in the response requirement early in shaping increased variability. Postacquisition variability remained unchanged in the number of responses per sequence-the aspect of responding on which reinforcement was contingent-but declined in location and timing of keypressing. The results are discussed in terms of the implicit reinforcement of variability and how the acquisition of qualitatively different response strategies could influence variability.