Charles Sherrington identified the properties of the synapse by purely behavioral means—the study of reflexes—more than 100 years ago. They were subsequently confirmed neurophysiologically. Studying reflex interaction, he also showed that activating one reflex often facilitates another, antagonistic one: successive induction, which has since been demonstrated in a wide range of species, from aphids to locusts to dogs and humans. We show a particularly orderly example in zebrafish (Danio rerio) larvae; the behavior (locomotion) of larvae is low in dark and intermediate in light, but low in light and substantially higher in dark when dark followed light. A quantitative model of a simple dynamic process is described that readily captures the behavior pattern and the effects of a number of manipulations of lighting conditions.
Research on animal metacognition has typically used choice discriminations whose difficulty can be varied. Animals are given some opportunity to escape the discrimination task by emitting a so-called uncertain response. The usual claim is that an animal possesses metacognition if (a) the probability of picking the uncertain response increases with task difficulty, and (b) animals are more accurate on “free-choice” trials —i.e., trials where the uncertain response was available but was not chosen—than on “forced-choice” trials, where the uncertain response is unavailable. We describe a simple behavioral economic model (BEM), based on familiar learning principles, and thus lacking any metacognition construct, which is able to meet both criteria in most of these tasks. We conclude that rather than designing ever more complex experiments to identify “metacognition,” a necessarily ill-defined concept, knowledge might better be advanced not by further refining behavioral criteria for the concept, but by the development and testing of theoretical models for the clever behavior that many animals show in these experiments.
Professor Hocutt and I agree that David Hume first pointed out that “ought”—what should be done—cannot be derived from “is”—what is the case. Hocutt goes on to claim that “ought,” in fact, derives from factual observation of “what we care about,” which amounts to saying “you should do what you want to do.” This seems to me unsatisfactory as moral philosophy.
We propose a simple behavioral economic model (BEM) describing how reinforcement and interval timing interact. The model assumes a Weber-law-compliant logarithmic representation of time. Associated with each represented time value are the payoffs that have been obtained for each possible response. At a given real time, the response with the highest payoff is emitted. The model accounts for a wide range of data from procedures such as simple bisection, metacognition in animals, economic effects in free-operant psychophysical procedures and paradoxical choice in double-bisection procedures. Although it assumes logarithmic time representation, it can also account for data from the time-left procedure usually cited in support of linear time representation. It encounters some difficulties in complex free-operant choice procedures, such as concurrent mixed fixed-interval schedules as well as some of the data on double bisection, that may involve additional processes. Overall, BEM provides a theoretical framework for understanding how reinforcement and interval timing work together to determine choice between temporally differentiated reinforcers.
Why stop signs and speed limits endanger Americans.
"Metacognition" in animals can be explained by familiar learning principles...
ats, people, and many other omnivores eat in meals rather than continuously. We show by experimental test that eating in meals is regulated by a simple bang-bang control system, an idea foreshadowed by Le Magnen and many others, shown by us to account for a wide range of behavioral data, but never explicitly tested or tied to neurophysiological facts. The hypothesis is simply that the tendency to eat rises with time at a rate determined by satiety signals. When these signals fall below a set point, eating begins, in on–off fashion. The delayed sequelae of eating increment the satiety signals, which eventually turn eating off. Thus, under free conditions, the organism eats in bouts separated by noneating activities. We report an experiment with rats to test novel predictions about meal patterns that are not explained by existing homeostatic approaches. Access to food was systematically but unpredictably interrupted just as the animal tried to start a new meal. A simple bang-bang model fits the resulting meal-pattern data well, and its elements can be identified with neurophysiological processes. Hypothalamic inputs can provide the set point for longer-term regulation carried out by a comparator in the hindbrain. Delayed gustatory and gastrointestinal aftereffects of eating act via the nucleus of the solitary tract and other hindbrain regions as neural feedback governing short-term regulation. In this way, the model forges real links between a functioning feedback mechanism, neuro–hormonal data, and both short-term (meals) and long-term (eating-rate regulation) behavioral data.
Interval timing, anticipation of periodic events signalled by a time marker, has been explained by a separate pacemaker-counter clock. But recent theoretical work suggests that memory strength can act as clock. The way that memory strength declines with time can be inferred from the properties of habituation and the same process provides a parsimonious explanation for proportional timing, the Weber-law property and several other proper-ties of interval timing.
E. O. Wilson and B. F. Skinner have argued for an evolutionary ethics that allows what ought to be to be derived from what is, ethics from science. But evolution is inherently unpredictable. Some practices whose benefits cannot be proved may nevertheless turn out to be good for the survival of a culture or the race. Others that seem good may turn out to be bad. Consequently the evolutionary argument implies that a successful culture will believe some things that cannot be proved. It also tells us we cannot know in advance what those things will be.
Operant behavior is behavior “controlled” by its consequences. In practice operant conditioning is the study of reversible behavior maintained by reinforcement schedules. We review empirical studies and theoretical approaches to two large classes of operant behavior: interval timing and choice. We discuss cognitive vs. behavioral approaches to timing, the “gap” experiment and its implications, proportional timing and Weber’s law, temporal dynamics and linear waiting and the problem of simple chain-interval schedules. We review the long history of research on operant choice: the matching law, its extensions and problems, concurrent chain schedules and self control. We point out how linear waiting may be involved in timing, choice and reinforcement schedules generally. There are prospects for a unified approach to all these areas.
Memory decay is rapid at first and slower later—a feature that accounts for Jost’s memory law: that old memories gain on newer ones with lapse of time. The rate-sensitive property of habituation—that recovery after spaced stimuli may be slower than after massed—provides a clue to the dynamics of memory decay. Rate-sensitive habituation can be modeled by a cascade of thresholded integrator units that have a counterpart in human brain areas identified by magnetic source imaging (MSI). The memory trace component of the multiple-time-scale model for habituation can provide a ‘clock’ that has the properties necessary to account for both static and dynamic properties of interval timing: static proportional and Weber-law timing as well as dynamic tracking of progressive, ‘impulse’ and periodic interval sequences.
A popular view of interval timing in animals is that it is driven by a discrete pacemaker-accumulator (PA) mechanism that yields a linear scale for encoded time. But PA mechanisms are fundamentally at odds with the Weber-law property of interval timing and experiments supporting linear encoded time can be interpreted in other ways. We argue that the dominant PA theory, scalar expectancy theory (SET), fails to explain some basic properties of operant behavior on interval-timing procedures and can only accommodate a number of discrepancies by modifications and elaborations that raise questions about the entire theory. We propose an alternative that is based on principles of memory dynamics derived from the multiple-time-scale (MTS) model of habituation. The MTS timing model can account for data from a wide variety of time-related experiments: proportional and Weber-law temporal discrimination, transient as well as persistent effects of reinforcement omission and reinforcement magnitude, bisection, the discrimination of relative as well as absolute duration, the choose-short effect and its analogue in number-discrimination experiments. Resemblances between timing and counting are an automatic consequence of the model. We also argue that the transient and persistent effects of drugs on time estimates can be interpreted as well within MTS theory as in SET. Recent real-time physiological data conform in surprising detail to the assumptions of the MTS habituation model. Comparisons between the two views suggest a number of novel experiments.
See also comments from seven other researchers in this issue of JEAB.
A popular view of interval timing in animals is that it is driven by a discrete pacemaker-accumulator (PA) mechanism that yields a linear scale for encoded time. But PA mechanisms are fundamentally at odds with the Weber-law property of interval timing and experiments supporting linear encoded time can be interpreted in other ways. We argue that the dominant PA theory, scalar expectancy theory (SET), fails to explain some basic properties of operant behavior on interval-timing procedures and can only accommodate a number of discrepancies by modifications and elaborations that raise questions about the entire theory. We propose an alternative that is based on principles of memory dynamics derived from the multiple-time-scale (MTS) model of habituation. The MTS timing model can account for data from a wide variety of time-related experiments: proportional and Weber-law temporal discrimination, transient as well as persistent effects of reinforcement omission and reinforcement magnitude, bisection, the discrimination of relative as well as absolute duration, the choose-short effect and its analogue in number-discrimination experiments. Resemblances between timing and counting are an automatic consequence of the model. We also argue that the transient and persistent effects of drugs on time estimates can be interpreted as well within MTS theory as in SET. Recent real-time physiological data conform in surprising detail to the assumptions of the MTS habituation model. Comparisons between the two views suggest a number of novel experiments.
See also commentaries by seven other researchers in this issue.
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