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Friedrich, A. M., Clement, T. S., & Zentall, T. R. (2004). Functional equivalence in pigeons involving a four-member class. Behav. Process., 67(3), 395–403.
Abstract: Research suggests that animals are capable of forming functional equivalence relations or stimulus classes of the kind usually demonstrated by humans (e.g., the class defined by an object and the word for that object). In pigeons, such functional equivalences are typically established using many-to-one matching-to-sample in which two samples are associated with one comparison stimulus and two different samples are associated with the other. Evidence for the establishment of functional equivalences between samples associated with the same comparison comes from transfer tests. In Experiment 1, we found that pigeons can form a single class consisting of four members (many-to-one matching) when the alternative class has only one member (one-to-one matching). In Experiment 2, we ruled out the possibility that the pigeons acquired the hybrid one-to-one/many-to-one task by developing a single-code/default coding strategy as earlier research suggested that it might. Thus, pigeons can develop a functional class consisting of as many as four members, with the alternative class consisting of a single member.
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Zentall, T. R. (2005). Selective and divided attention in animals. Behav. Process., 69(1), 1–15.
Abstract: This article reviews some of the research on attentional processes in animals. In the traditional approach to selective attention, it is proposed that in addition to specific response attachments, animals also learn something about the dimension along which the stimuli fall (e.g., hue, brightness, or line orientation). More recently, there has been an attempt to find animal analogs to methodologies originally applied to research with humans. One line of research has been directed to the question of whether animals can locate a target among distracters faster if they are prepared for the presentation of the target (search image and priming). In the study of search image, the target is typically a food item and the cue consists of previous trials on which the same target is presented. In research on priming effects, the cue is typically different from the target but is a good predictor of its occurrence. The study of preattentive processes shows that perceptually, certain stimuli stand out from distracters better than others, depending not only on characteristics of the target relative to the distracters, but also on relations among the distracters. Research on divided attention is examined with the goal of determining whether an animal can process two elements of a compound sample with the same efficiency as one. Taken together, the reviewed research indicates that animals are capable of centrally (not just peripherally) attending to selective aspects of a stimulus display.
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Zentall, T. R. (2005). Timing, memory for intervals, and memory for untimed stimuli: the role of instructional ambiguity. Behav. Process., 70(3), 209–222.
Abstract: Theories of animal timing have had to account for findings that the memory for the duration of a timed interval appears to be dramatically shorted within a short time of its termination. This finding has led to the subjective shortening hypothesis and it has been proposed to account for the poor memory that animals appear to have for the initial portion of a timed interval when a gap is inserted in the to-be-timed signal. It has also been proposed to account for the poor memory for a relatively long interval that has been discriminated from a shorter interval. I suggest here a simpler account in which ambiguity between the gap or retention interval and the intertrial interval results in resetting the clock, rather than forgetting the interval. The ambiguity hypothesis, together with a signal salience mechanism that determines how quickly the clock is reset at the start of the intertrial interval can account for the results of the reported timing experiments that have used the peak procedure. Furthermore, instructional ambiguity rather than memory loss may account for the results of many animal memory experiments that do not involve memory for time.
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Zentall, T. R. (2006). Timing, memory for intervals, and memory for untimed stimuli: The role of instructional ambiguity. Behav. Process., 71(2-3), 88–97.
Abstract: Theories of animal timing have had to account for findings that the memory for the duration of a timed interval appears to be dramatically shorted within a short time of its termination. This finding has led to the subjective shortening hypothesis and it has been proposed to account for the poor memory that animals appear to have for the initial portion of a timed interval when a gap is inserted in the to-be-timed signal. It has also been proposed to account for the poor memory for a relatively long interval that has been discriminated from a shorter interval. I suggest here a simpler account in which ambiguity between the gap or retention interval and the intertrial interval results in resetting the clock, rather than forgetting the interval. The ambiguity hypothesis, together with a signal salience mechanism that determines how quickly the clock is reset at the start of the intertrial interval can account for the results of the reported timing experiments that have used the peak procedure. Furthermore, instructional ambiguity rather than memory loss may account for the results of many animal memory experiments that do not involve memory for time.
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Zentall, T. R. (2006). Mental time travel in animals: a challenging question. Behav. Process., 72(2), 173–183.
Abstract: Humans have the ability to mentally recreate past events (using episodic memory) and imagine future events (by planning). The best evidence for such mental time travel is personal and thus subjective. For this reason, it is particularly difficult to study such behavior in animals. There is some indirect evidence, however, that animals have both episodic memory and the ability to plan for the future. When unexpectedly asked to do so, animals can report about their recent past experiences (episodic memory) and they also appear to be able to use the anticipation of a future event as the basis for a present action (planning). Thus, the ability to imagine past and future events may not be uniquely human.
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Zentall, T. R. (1999). Support for a theory of memory for event duration must distinguish between test-trial ambiguity and actual memory loss. J Exp Anal Behav, 72(3), 467–472.
Abstract: Staddon and Higa's (1999) trace-strength theory of timing and memory for event duration can account for pigeons' bias to “choose short” when retention intervals are introduced and to “choose long” when, following training with a fixed retention interval, retention intervals are shortened. However, it does not account for the failure of pigeons to choose short when the intertrial interval is distinct from the retention interval. That finding suggests that stimulus generalization (or ambiguity) between the intertrial interval and the retention interval may result in an effect that has been attributed to memory loss. Such artifacts must be eliminated before a theory of memory for event duration can be adequately tested.
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Zentall, T. R. (2007). Temporal discrimination learning by pigeons. Behav. Process., 74(2), 286–292.
Abstract: Memory for time by animals appears to undergo a systematic shortening. This so-called choose-short effect can be seen in a conditional temporal discrimination when a delay is inserted between the sample and comparison stimuli. We have proposed that this temporal shortening may result from a procedural artifact in which the delay appears similar to the intertrial interval and thus, produces an inadvertent ambiguity or 'instructional failure'. When this ambiguity is avoided by distinguishing the intertrial interval from the delay, as well as the samples from the delay, the temporal shortening effect and other asymmetries often disappear. By avoiding artifacts that can lead to a misinterpretation of results, we may understand better how animals represent time. An alternative procedure for studying temporal discriminations is with the psychophysical bisection procedure in which following conditional discrimination training, intermediate durations are presented and the point of subjective equality is determined. Research using the bisection procedure has shown that pigeons represent temporal durations not only as their absolute value but also relative to durations from which they must be discriminated. Using this procedure, we have also found that time passes subjectively slower when animals are required to respond to the to-be-timed stimulus.
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Zentall, T. R., Galizio, M., & Critchfied, T. S. (2002). Categorization, concept learning, and behavior analysis: an introduction. J Exp Anal Behav, 78(3), 237–248.
Abstract: Categorization and concept learning encompass some of the most important aspects of behavior, but historically they have not been central topics in the experimental analysis of behavior. To introduce this special issue of the Journal of the Experimental Analysis of Behavior (JEAB), we define key terms; distinguish between the study of concepts and the study of concept learning; describe three types of concept learning characterized by the stimulus classes they yield; and briefly identify several other themes (e.g., quantitative modeling and ties to language) that appear in the literature. As the special issue demonstrates, a surprising amount and diversity of work is being conducted that either represents a behavior-analytic perspective or can inform or constructively challenge this perspective.
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Nallan, G. B., Pace, G. M., McCoy, D. F., & Zentall, T. R. (1979). Temporal parameters of the feature positive effect. Am J Psychol, 92(4), 703–710.
Abstract: Trial duration and intertrial interval duration were parametrically varied between groups of pigeons exposed to a discrimination involving the presence vs. the absence of a dot. Half the groups received the dot as the positive stimulus (feature positive groups) and half the groups received the dot as the negative stimulus (feature negative groups). Faster learning by the feature positive birds (feature positive effect) was found when the trial duration was short (5 sec) regardless of whether the intertrial interval was short (5 sec) or long (30 sec). No evidence for a feature positive effect was found when the trial duration was long (30 sec) regardless of the length of the intertrial interval (30 sec or 180 sec). The results suggest that short trial duration is a necessary condition for the occurrence of the feature positive effect, and neither intertrial interval nor trial duration/intertrial interval ratio are important for its occurrence. The suggestion that mechanisms underlying the feature positive effect and autoshaping might be similar was not supported by the present experiment since the trial duration/intertrial interval ration parameter appears to play an important role in autoshaping but not the feature positive effect.
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Zentall, S. S., & Zentall, T. R. (1983). Optimal stimulation: a model of disordered activity and performance in normal and deviant children. Psychol Bull, 94(3), 446–471.
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