bluuebunny/crossref_metadata_2025 huggingface dataset:
RESIDENCE TIME IN CONCURRENT FORAGING WITH FIXED TIMES TO PREY ARRIVAL
Authors: Davison Michael , Jones B. Max
Published: March 2006

Five pigeons were trained in a concurrent foraging procedure in which reinforcers were occasionally available after fixed times in two discriminated patches. In Part 1 of the experiment, the fixed times summed to 10 s, and were individually varied between 1 and 9 s over five conditions, with the probability of a reinforcer being delivered at the fixed times always .5. In Part 2, both fixed times were 5 s, and the probabilities of food delivery were varied over conditions, always summing to 1.0. In Parts 3 and 4, one fixed time was kept constant (Part 3, 3 s; Part 4, 7 s) while the other fixed time was varied from 1 s to 15 s. Median residence times in both patches increased with increases in the food‐arrival times in either patch, but increased considerably more strongly in the patch in which the arrival time was increased. However, when arrival times were very different in the two patches, residence time in the longer arrival‐time patch often decreased. Patch residence also increased with increasing probability of reinforcement, but again tended to fall when one probability was much larger than the other. A detailed analysis of residence times showed that these comprised two distributions, one around a shorter mode that remained constant with changes in arrival times, and one around a longer mode that monotonically increased with increasing arrival time. The frequency of shorter residence times appeared to be controlled by the probability of, and arrival time of, reinforcers in the alternative patch. The frequency of longer residence times was controlled directly by the arrival time of reinforcers in a patch, but not by the probability of reinforcers in a patch. The environmental variables that control both staying in a patch and exiting from a patch need to be understood in the study both of timing processes and of foraging.
THE S‐R ISSUE: ITS STATUS IN BEHAVIOR ANALYSIS AND IN DONAHOE AND PALMER'S LEARNING AND COMPLEX BEHAVIOR
Authors: Donahoe John W. , Palmer David C. , Burgos José E.
Published: March 2006

The central focus of this essay is whether the effect of reinforcement is best viewed as the strengthening of responding or the strengthening of the environmental control of responding. We make the argument that adherence to Skinner's goal of achieving a moment‐to‐moment analysis of behavior compels acceptance of the latter view. Moreover, a thoroughgoing commitment to a moment‐to‐moment analysis undermines the fundamental distinction between the conditioning processes instantiated by operant and respondent contingencies while buttressing the crucially important differences in their cumulative outcomes. Computer simulations informed by experimental analyses of behavior and neuroscience are used to illustrate these points.
MEAL PATTERNS OF CATS ENCOUNTERING VARIABLE FOOD PROCUREMENT COST
Authors: Collier George , Johnson Deanne F. , Morgan Cynthia
Published: March 2006

The meal patterns of 2 cats in a laboratory habitat with variable foraging costs were examined in a foraging paradigm in which subjects could initiate meals at any time by completing a predetermined number of bar presses (the procurement price) and then could eat any amount. From meal to meal, the procurement price either was fixed or varied among a geometric series of five prices. As the fixed price or the mean of the variable prices increased, meal frequency decreased and meal size increased; daily intake was unaffected. Within variable‐price schedules, meal size was not related to the just‐paid procurement price. These results suggest that cats respond to the global rather than to the local cost structure of their habitat. They appear to respond to an average of the prices encountered, initiating meals of a frequency and size appropriate to that average. This was true even when the average price was high, meals were infrequent, and thus price encounters were widely separated in time. Therefore, the time window over which the consequences of behavior can affect behavior is longer than often conceived, at least in economies in which the animal controls its intake and the frequency, size, and distribution of its meals.
EFFECTS OF HISTORIES OF DIFFERENTIAL REINFORCEMENT OF RESPONSE RATE ON VARIABLE‐INTERVAL RESPONDING
Authors: Ono Koichi , Iwabuchi Keiko
Published: March 2006

Three pigeons were exposed first to multiple differential‐reinforcement‐of‐high‐rate and differential‐reinforcement‐of‐low‐rate schedules that were correlated with green and red keys, respectively, and then were shifted to a variable‐interval schedule arranged on a white key. In subsequent test sessions, the variable‐interval schedule continued to operate, but green and red keys replaced the white key in alternate sessions. In Part 1 of the experiment, the variable‐interval schedule correlated with the white key was introduced immediately after the multiple‐schedule condition, and the test condition began 15 days later. This sequence was repeated twice, with a reversal of the correlation of the key colors with the components of the multiple schedule at the start of each new cycle. Part 2 added a 6‐month break between the multiple‐schedule history and the white‐key variable‐interval schedule followed by test sessions. The procedure was then repeated with a reversal of the correlation between key colors and multiple‐schedule components. In the test sessions of Part 1, all pigeons consistently responded faster in the presence of the key color most recently correlated with the differential‐reinforcement‐of‐high‐rate contingency than during the color most recently correlated with the differential‐reinforcement‐of‐low‐rate contingency. Similar but smaller effects were observed in Part 2. The effects of the reversals in these two parts of the experiment showed that only the most recent contingency exerted an influence on subsequent responding. The data suggest that this effect of the most recent history continues to operate on behavior under current contingencies even after a long lapse of time.
MEMORY PROCESSES IN DELAYED SPATIAL DISCRIMINATIONS: RESPONSE INTENTIONS OR RESPONSE MEDIATION?
Authors: Urcuioli Peter J. , Demarse Thomas B.
Published: March 2006

Pigeons were trained on a pair‐comparison task in which left versus right choices were reinforced following different sequences of two center‐key stimuli. Choice accuracy was higher when retention intervals occurred after the entire sequence than when they separated the two stimuli comprising it, and this effect occurred independently of whether the initial and terminal stimuli came from the same or different dimensions. The initial stimulus from the prior trial was a source of proactive interference only in groups for which the retention interval separated the two sequence stimuli. By contrast, differential delay‐interval behavior was observed only in groups for which the retention interval followed presentation of the entire sequence. These results indicate that coding processes in delayed discriminations are influenced by the location of the retention interval, and that response mediation affects retention performances if the reinforced choice can be determined prior to the interval.
DETERMINATION OF DISCOUNT FUNCTIONS IN RATS WITH AN ADJUSTING‐AMOUNT PROCEDURE
Authors: Richards Jerry B. , Mitchell Suzanne H. , de Wit Harriet , Seiden Lewis S.
Published: March 2006

An adjusting‐amount procedure was used to measure discounting of reinforcer value by delay. Eight rats chose between a varying amount of immediate water and a fixed amount of water given after a delay The amount of immediate water was systematically adjusted as a function of the rats' previous choices. This procedure was used to determine the indifference point at which each rat chose the immediate amount and the delayed amount with equal frequency. The amount of immediate water at this indifference point was used to estimate the value of the delayed amount of water. In Experiment 1, the effects of daily changes in the delay to the fixed reinforcer (100 μl of water delivered after 0, 2, 4, 8, or 16 s) were tested. Under these conditions, the rats reached indifference points within the first 30 trials of each 60‐trial session. In Experiment 2, the effects of water deprivation level on discounting of value by delay were assessed. Altering water deprivation level affected the speed of responding but did not affect delay discounting. In Experiment 3, the effects of varying the magnitude of the delayed water (100, 150, and 200 μl) were tested. There was some tendency for the discounting function to be steeper for larger than for smaller reinforcers, although this difference did not reach statistical significance. In all three experiments, the obtained discount functions were well described by a hyperbolic function. These experiments demonstrate that the adjusting‐amount procedure provides a useful tool for measuring the discounting of reinforcer value by delay.
KEY PECKING DURING EXTINCTION AFTER INTERMITTENT OR CONTINUOUS REINFORCEMENT AS A FUNCTION OF THE NUMBER OF REINFORCERS DELIVERED DURING TRAINING
Authors: Zarcone Troy J. , Branch Marc N. , Hughes Christine E. , Pennypacker Henry S.
Published: March 2006

Key pecking by 7 pigeons was established and maintained on a multiple variable‐ratio variable‐ratio (VR) schedule of food presentation. The schedule in one of the components was then changed to fixed‐ratio (FR) 1 for a predetermined number of reinforcers. Both components were then changed to extinction (i.e., multiple extinction, extinction). This sequence was repeated a different number of times for each pigeon to determine the relation between the number of reinforcers delivered during each component of the multiple VR FR 1 schedule and the number of responses during extinction. For most pigeons, there were fewer responses during extinction in the presence of a stimulus recently correlated with FR 1, regardless of the number of reinforcers received. The ratio of the total responses in extinction in the former VR component to the total responses in the former FR 1 component increased as the number of reinforcers delivered during each component of the multiple schedule increased. Within‐subject replications of the partial‐reinforcement extinction effect generally occurred, and there were no overall reductions in the number of responses in extinction with repeated exposures to extinction.
INCREASING THE VARIABILITY OF RESPONSE SEQUENCES IN PIGEONS BY ADJUSTING THE FREQUENCY OF SWITCHING BETWEEN TWO KEYS
Authors: Machado Armando
Published: March 2006

Three experiments compared the amounts of behavioral variability generated with two reinforcement rules. In Experiments 1 and 2 pigeons received food whenever they generated a sequence of eight pecks, distributed over two keys, provided that the sequence contained a certain number of changeovers between the keys. Although no variability was required—the birds could obtain all reinforcers by repeating the same sequence—the pigeons emitted a large number of different sequences. In Experiment 3 pigeons received food whenever they generated a sequence that had not occurred during the last 25 trials. After prolonged training, the birds showed more sequence variability than in the first two experiments. The analysis of the internal structure of the response sequences revealed that, in general, (a) the location of the first peck was highly stereotyped; (b) as the trial advanced, the probability of switching to the initially preferred key decreased whereas the probability of switching to the other key increased; and (c) a first‐order Markov chain model with transition probabilities given by a logistic function accounted well for the internal structure of the birds' response sequences. These findings suggest that, to a large extent, the variability of response sequences is an indirect effect of adjustments in changeover frequency.
COMPARING LOCOMOTION WITH LEVER‐PRESS TRAVEL IN AN OPERANT SIMULATION OF FORAGING
Authors: Aparicio Carlos F. , Baum William M.
Published: March 2006

An operant model of foraging was studied. Rats searched for food by pressing on the left lever, the patch, which provided one, two, or eight reinforcers before extinction (i.e., zero reinforcers). Obtaining each reinforcer lowered the probability of receiving another reinforcer, simulating patch depletion. Rats traveled to another patch by pressing the right lever, which restored reinforcer availability to the left lever. Travel requirement changed by varying the probability of reset for presses on the right lever; in one condition, additional locomotion was required. That is, rats ran 260 cm from the left to the right lever, made one response on the right lever, and ran back to a fresh patch on the left lever. Another condition added three hurdles to the 260‐cm path. The lever‐pressing and simple locomotion conditions generated equivalent travel times. Adding the hurdles produced longer times in patches than did the lever‐pressing and simple locomotion requirements. The results contradict some models of optimal foraging but are in keeping with McNair's (1982) optimal giving‐up time model and add to the growing body of evidence that different environments may produce different foraging strategies.
DRUG DISCRIMINATION UNDER A CONCURRENT FIXED‐INTERVAL FIXED‐INTERVAL SCHEDULE
Authors: McMillan D. E. , Li Mi , Hardwick W. C.
Published: March 2006

Pigeons were trained to discriminate 5.0 mg/kg pentobarbital from saline under a concurrent fixed‐interval (FI) FI schedule of food presentation on which, after pentobarbital administration, responses on one key were reinforced with food under an FI 60‐s component and responses on the other key were reinforced under an FI 240‐s component. After saline administration, the schedule contingencies on the two keys were reversed. After both pentobarbital and saline, pigeons responded more frequently on the key on which responses had been programmed to produce the reinforcer under the FI 60 component of the concurrent schedule. The schedule was changed to concurrent FI 150 FI 150 s for drug‐substitution tests. In each bird, increasing doses of pentobarbital, ethanol, and chlordiazepoxide produced increases in the proportion of responses on the key on which responses had been reinforced under the FI 60 component after pentobarbital administration during training sessions. The proportion of responses on that key was slightly lower for ethanol than for chlordiazepoxide and pentobarbital. At a dose of pentobarbital higher than the training dose, responding decreased on the key that had been reinforced under the FI 60 component during training sessions. Phencyclidine produced less responding on the key programmed under the FI 60‐s component than did pentobarbital. Methamphetamine produced responding primarily on the key on which responses had been reinforced under the FI 60‐s component after saline administration.
MATCHING‐TO‐SAMPLE PERFORMANCE IN RATS: A CASE OF MISTAKEN IDENTITY?
Authors: Iversen Iver H.
Published: March 2006

Three rats had previously acquired a simultaneous matching‐to‐sample performance with steady and blinking lights. In training, the sample stimulus had always appeared on the middle of three horizontally arranged keys with the comparison stimuli on the side keys. In Experiment 1, the sample stimulus appeared on any of the three keys with the comparison stimuli on the remaining two. The matching‐to‐sample performance broke down with variable sample and comparison locations; the sample stimulus did not control responding to the comparison stimuli when it appeared on a side key, but it retained control when it appeared on the middle key (as in training). In Experiment 2, the rats were trained with the sample always on the left key. When the sample appeared on either of the trained locations (left or middle key), it retained control for both locations. When the sample then appeared on any of the three keys, as in Experiment 1, sample control did not transfer to the untrained location (right key). The experiments demonstrate that training with fixed sample and comparison locations may establish spatial location as an additional controlling aspect of the stimuli displayed on the keys; stimulus location had become part of the definition of the controlling stimuli. The rats' performance seemed best described as specific discriminations involving the visual stimuli and their spatial locations rather than as identity matching.
TOWARD A THEORY OF VERBAL BEHAVIOR
Authors: Horne Pauline J. , Lowe C. Fergus
Published: March 2006

This paper is a reply to an accompanying set of six commentaries by Sidman; Hayes and Barnes; Schusterman, Kastak, and Reichmuth; Tonneau and Sokolowski; Lowenkron; and Moerk. Those commentaries were prompted by our article “On the Origins of Naming and Other Symbolic Behavior” (1996), which was, in turn, followed by 26 commentaries and a reply. In the course of the present reply, we further develop the naming account to embrace more complex verbal relations such as same, different, more, and less. We also examine what we see as the lack of conceptual coherence in equivalence theories, including relational frame theory, and the disparities between these accounts and the findings from empirical research.
REINFORCER FREQUENCY AND RESTRICTED STIMULUS CONTROL
Authors: Dube William V. , McIlvane William J.
Published: March 2006

Stimulus control was evaluated in 3 individuals with moderate to severe mental retardation by delayed identity matching‐to‐sample procedures that presented either one or two discrete forms as sample stimuli on each trial. On pretests, accuracy scores on one‐sample trials were uniformly high. On two‐sample trials, the correct stimulus (i.e., the one that subsequently appeared in the comparison array) varied unpredictably, and accuracy scores were substantially lower, suggesting that both sample stimuli did not exert stimulus control on every trial. Subjects were then given training sessions with the one‐sample task and with a new set of four stimuli. For two of the stimuli, correct matching responses were followed by reinforcers on a variable‐ratio schedule that led to a high reinforcer rate. For the other two stimuli, correct responses were followed by reinforcers on a variable‐ratio schedule that led to a substantially lower reinforcer rate. Results on two‐sample tests that followed showed that (a) on trials in which comparison arrays consisted of one high reinforcer‐rate and one low reinforcer‐rate stimulus, subjects most often selected the high‐rate stimulus; and (b) on trials in which the comparison arrays were either two high reinforcer‐rate stimuli or two low reinforcer‐rate stimuli and the samples were one high reinforcer‐ and one low reinforcer‐rate stimulus, accuracy was higher on trials with the high‐rate comparisons. These results indicate that the frequency of stimulus control by high reinforcer‐rate samples was greater than that by low reinforcer‐rate samples. Following more training with the one‐sample task and reversed reinforcement schedules for all stimuli, the differences in stimulus control frequencies on two‐sample tests also reversed. These results demonstrate experimental control by reinforcement contingencies of which of two sample stimuli controlled selections in the two‐sample task. The procedures and results may prove to be relevant for understanding restricted stimulus control and stimulus overselectivity.
CONTIGUITY AND CONDITIONED REINFORCEMENT IN PROBABILISTIC CHOICE
Authors: McDevitt Margaret A. , Spetch Marcia L. , Dunn Roger
Published: March 2006

In a baseline condition, pigeons chose between an alternative that always provided food following a 30‐s delay (100% reinforcement) and an alternative that provided food half of the time and blackout half of the time following 30‐s delays (50% reinforcement). The different outcomes were signaled by different‐colored keylights. On average, each alternative was chosen approximately equally often, replicating the finding of suboptimal choice in probabilistic reinforcement procedures. The efficacy of the delay stimuli (keylights) as conditioned reinforcers was assessed in other conditions by interposing a 5‐s gap (keylights darkened) between the choice response and one or more of the delay stimuli. The strength of conditioned reinforcement was measured by the decrease in choice of an alternative when the alternative contained a gap. Preference for the 50% alternative decreased in conditions in which the gap preceded either all delay stimuli, both delay stimuli for the 50% alternative, or the food stimulus for the 50% alternative, but preference was not consistently affected in conditions in which the gap preceded only the 100% delay stimulus or the blackout stimulus for the 50% alternative. These results support the notion that conditioned reinforcement underlies the finding of suboptimal preference in probabilistic reinforcement procedures, and that the signal for food on the 50% reinforcement alternative functions as a stronger conditioned reinforcer than the signal for food on the 100% reinforcement alternative. In addition, the results fail to provide evidence that the signal for blackout functions as a conditioned punisher.
FOOD AND AMPHETAMINE SELF‐ADMINISTRATION BY BABOONS: EFFECTS OF ALTERNATIVES
Authors: Foltin Richard W.
Published: March 2006

The effects of the availability of an alternative reinforcer on responding maintained by food pellets or fluid solutions were examined in 6 adult male baboons (Papio cynocephalus anubis). During daily 23‐hr experimental sessions, baboons had concurrent access to both food pellets and fluid, with responding maintained under fixed‐ratio schedules of reinforcement that varied between the two commodities. The fixed‐ratio requirement, or cost, for pellets was increased when (a) no fluid, (b) a dilute dextrose vehicle, (c) 0.002 mg/kg d‐amphetamine, or (d) 0.004 mg/kg d‐amphetamine was available. When given nonrestricted concurrent access to food pellets and amphetamine at minimal cost (FR 2), baboons self‐administered sufficient amphetamine to decrease pellet intake. Increasing the response requirement for pellets decreased pellet intake at a similar rate regardless of the available fluid and increased fluid intake in a variable manner among baboons such that there were no statistically significant increases in fluid intake. In contrast, when access to pellets was restricted to 70% of maximal intake under nonrestricted conditions, increasing pellet cost decreased pellet intake and increased fluid intake more rapidly when the high amphetamine dose was available. Thus, amphetamine was more effective as an economic substitute for pellets when access to pellets was restricted. The response cost for vehicle and both amphetamine concentrations was increased when baboons had nonrestricted and restricted access to pellets. Increasing the response requirement for fluid delivery decreased intake of all three fluids similarly under both pellet‐access conditions. The results indicate that substitution between commodities with minimal commonalities can be studied under controlled laboratory conditions and is dependent upon reinforcement schedule and commodity restrictions.
PREDICTING THE EXTENSION OF EQUIVALENCE CLASSES FROM PRIMARY GENERALIZATION GRADIENTS: THE MERGER OF EQUIVALENCE CLASSES AND PERCEPTUAL CLASSES
Authors: Fields Lanny , Reeve Kenneth F. , Adams Barbara J. , Brown John L. , Verhave Thom
Published: March 2006

In Experiment 1, 6 college students were given generalization tests using 25 line lengths as samples with a long line, a short line, and a “neither” option as comparisons. The neither option was to be used if a sample did not go with the other comparisons. Then, four‐member equivalence classes were formed. Class 1 included three nonsense words and the short line. Class 2 included three other nonsense words and the long line. After repeating the generalization test for line length, additional tests were conducted using members of the equivalence classes (i.e., nonsense words and lines) as comparisons and intermediate‐length lines as samples. All Class 2 comparisons were selected in the presence of the test lines that also evoked the selection of the long line in the generalization test that had been given before equivalence class formation. Class 1 yielded complementary findings. Thus, the preclass primary generalization gradient predicted which test lines acted as members of each equivalence class. Regardless of using comparisons that were nonsense words or lines, the post‐class‐formation gradients overlapped, showing the substitutability of class members. Experiment 2 assessed the discriminability of the intermediate‐length test lines from the Class 1 (shortest) and Class 2 (longest) lines. The test lines that functioned as members of an equivalence class were discriminable from the line that was a member of the same class by training. Thus, these test lines also acted as members of a dimensionally defined class of “long” or “short” lines. Extension of an equivalence class, then, involved its merger with a dimensionally defined class, which converted a close‐ended class to an open‐ended class. These data suggest a means of predicting class membership in naturally occurring categories.
TRANSFER TESTS OF STIMULUS VALUE IN CONCURRENT CHAINS
Authors: Grace Randolph C. , Savastano Hernán I.
Published: March 2006

We report two experiments that use transfer tests to investigate whether in concurrent chains the value of a terminal‐link stimulus is affected by the alternate terminal link. In Experiment 1, two groups of pigeons were trained on multiple concurrent‐chains schedules in which switching between the schedules was via pecking a changeover key. For one group, the terminal links were fixed‐interval 8 s versus fixed‐interval 16 s in one component and fixed‐interval 16 s versus fixed‐interval 32 s in the other component. For a second group, the terminal links were variable‐interval 10 s versus variable‐interval 20 s in one component and variable‐interval 20 s versus variable‐interval 40 s in the other. After sufficient baseline training had been given so that performances had stabilized, transfer tests were conducted in which the two chains with equal terminal‐link schedules were presented together as a new concurrent pair. For 6 of the 7 subjects, initial‐link responding changed fairly rapidly during the test in the manner predicted if the values of the terminal links were equal. In Experiment 2, pigeons were trained on multiple concurrent chains using a two‐key procedure, and the terminal links were the same variable‐interval schedules as in Experiment 1. After baseline training, transfer tests were conducted that assessed (a) the relative reinforcing strength of the terminal‐link stimuli in a novel initial‐link situation and (b) the relative ability of those stimuli to evoke responding. The data from the reinforcing strength test were consistent with those from Experiment 1, but those from the evocation strength test were not. Although this discrepancy shows that responding in transfer tests is not solely a function of stimulus value, the results from both experiments suggest, overall, that value is determined by the stimulus—reinforcer relation independently of the alternative terminal link.
MECHANISMS UNDERLYING THE EFFECTS OF UNSIGNALED DELAYED REINFORCEMENT ON KEY PECKING OF PIGEONS UNDER VARIABLE‐INTERVAL SCHEDULES
Authors: Schaal David W. , Shahan Timothy A. , Kovera Craig A. , Reilly Mark P.
Published: March 2006

Three experiments were conducted to test an interpretation of the response‐rate‐reducing effects of unsignaled nonresetting delays to reinforcement in pigeons. According to this interpretation, rates of key pecking decrease under these conditions because key pecks alternate with hopper‐observing behavior. In Experiment 1, 4 pigeons pecked a food key that raised the hopper provided that pecks on a different variable‐interval‐schedule key met the requirements of a variable‐interval 60‐s schedule. The stimuli associated with the availability of the hopper (i.e., houselight and keylight off, food key illuminated, feedback following food‐key pecks) were gradually removed across phases while the dependent relation between hopper availability and variable‐interval‐schedule key pecks was maintained. Rates of pecking the variable‐interval‐schedule key decreased to low levels and rates of food‐key pecks increased when variable‐interval‐schedule key pecks did not produce hopper‐correlated stimuli. In Experiment 2, pigeons initially pecked a single key under a variable‐interval 60‐s schedule. Then the dependent relation between hopper presentation and key pecks was eliminated by arranging a variable‐time 60‐s schedule. When rates of pecking had decreased to low levels, conditions were changed so that pecks during the final 5 s of each interval changed the keylight color from green to amber. When pecking produced these hopper‐correlated stimuli, pecking occurred at high rates, despite the absence of a peck‐food dependency. When peck‐produced changes in keylight color were uncorrelated with food, rates of pecking fell to low levels. In Experiment 3, details (obtained delays, interresponse‐time distributions, eating times) of the transition from high to low response rates produced by the introduction of a 3‐s unsignaled delay were tracked from session to session in 3 pigeons that had been initially trained to peck under a conventional variable‐interval 60‐s schedule. Decreases in response rates soon after the transition to delayed reinforcement were accompanied by decreases in eating times and alterations in interresponse‐time distributions. As response rates decreased and became stable, eating times increased and their variability decreased. These findings support an interpretation of the effects of delayed reinforcement that emphasizes the importance of hopper‐observing behavior.
ON THE FUNCTIONS OF THE CHANGEOVER DELAY
Authors: Shahan Timothy A. , Lattal Kennon A.
Published: March 2006

The function of changeover delays in producing matching was examined with pigeons responding on concurrent variable‐interval variable‐interval schedules. In Experiment 1, no changeover delay was compared to two different types of changeover delay. One type, designated generically as response‐response but in the present example as peck‐peck, was timed from the first response on the switched‐to key; the other, designated generically as pause‐response but in the present example as pause‐peck, was timed from the last response on the switched‐from key. High changeover rates occurred with no changeover delay. Peck‐peck and pause‐peck changeover delays produced low and intermediate changeover rates, respectively. In Experiment 2, pause‐peck and peck‐peck changeover delays were compared across a range of relative reinforcement rates. Similar matching relations developed despite differences in the changeover rates and local response patterns as a function of the type of changeover delay. In Experiment 3, both types of changeover delay yielded similar changeover rates when their obtained durations were equal via yoking. The results suggest that changeover delays function to separate responses on one key from reinforcers on the other or to delay reinforcement for changing over. In addition, the distribution of responding during and after the changeover delay may vary considerably without affecting matching.
REPORTING CONTINGENCIES OF REINFORCEMENT IN CONCURRENT SCHEDULES
Authors: Jones B. Max , Davison Michael
Published: March 2006

Five pigeons were trained on concurrent variable‐interval schedules in which two intensities of yellow light served as discriminative stimuli in a switching‐key procedure. A conditional discrimination involving a simultaneous choice between red and green keys followed every reinforcer obtained from both alternatives. A response to the red side key was occasionally reinforced if the prior reinforcer had been obtained from the bright alternative, and a response to the green side key was occasionally reinforced if the prior reinforcer had been obtained from the dim alternative. Measures of the discriminability between the concurrent‐schedule alternatives were obtained by varying the reinforcer ratio for correct red and correct green responses across conditions in two parts. Part 1 arranged equal rates of reinforcement in the concurrent schedule, and Part 2 provided a 9:1 concurrent‐schedule reinforcer ratio. Part 3 arranged a 1:9 reinforcer ratio in the conditional discrimination, and the concurrent‐schedule reinforcer ratio was varied across conditions. Varying the conditional discrimination reinforcer ratio did not affect response allocation in the concurrent schedule, but varying the concurrent‐schedule reinforcer ratio did affect conditional discrimination performance. These effects were incompatible with a contingency‐discriminability model of concurrent‐schedule performance (Davison & Jenkins, 1985), which implies a constant discriminability parameter that is independent of the obtained reinforcer ratio. However, a more detailed analysis of conditional discrimination performance showed that the discriminability between the concurrent‐schedule alternatives decreased with time since changing over to an alternative. This effect, combined with aspects of the temporal distribution of reinforcers obtained in the concurrent schedules, qualitatively predicted the molar results and identified the conditions that operate whenever contingency discriminability remains constant.
HABITUATION TO THE REINFORCER MAY CONTRIBUTE TO MULTIPLE‐SCHEDULE BEHAVIORAL CONTRAST
Authors: McSweeney Frances K. , Weatherly Jeffrey N.
Published: March 2006

Habituation to the reinforcer may contribute to multiple‐schedule behavioral contrast. According to this argument, reducing reinforcers in one component of a multiple schedule reduces habituation to the reinforcer. Reducing habituation enhances the value, or effectiveness, of the remaining reinforcers, producing positive contrast. Enriching the reinforcers in one component increases habituation to that reinforcer. Increasing habituation decreases the effectiveness of the reinforcer, producing negative contrast. Such an idea is simple and parsimonious. It is not contradicted by any well‐established finding in the contrast literature. It makes several tested and untested predictions that are unusual. However, habituation cannot explain all contrast. A complete explanation requires postulating that at least one additional mechanism, controlled by the conditions of reinforcement in the following component, also contributes to contrast.
WHAT DOES A PIGEON SEE IN A PICASSO?
Authors: Monen Jos , Brenner Eli , Reynaerts Jenny
Published: March 2006

The present paper is primarily a response to Watanabe, Sakamoto, and Wakita's 1995 paper “Pigeons' Discrimination of Paintings by Monet and Picasso.” Our main criticism is that the key term concept, and in particular the way in which a class of stimuli is specified, remains equivocal. We argue that it is only useful to study categorization if the organism in question can be expected to have access to the information that is used in defining the classes, and that evidence for categorization requires selective responses that cannot be attributed to similarity in features that are not essential to the classification.
EFFECTS OF UNSIGNALED DELAY OF REINFORCEMENT ON PREFERENCE AND RESISTANCE TO CHANGE
Authors: Grace Randolph C. , Schwendiman Jed W. , Nevin John A.
Published: March 2006

In Phase 1, pigeons were trained on a concurrent chain in which a 3‐s unsignaled delay of reinforcement was imposed on responding in a terminal link in some conditions. Preference for that terminal link was always reduced in comparison with conditions in which there was no delay, substantially so for 3 of the 4 pigeons. In Phase 2, pigeons responded in a two‐component multiple schedule. The scheduled rates of reinforcement were equal, but a 3‐s unsignaled delay was imposed in one component. Resistance of responding to prefeeding and extinction was reduced in the delay component for the same 3 subjects for which the data had shown strong effects of delay on preference. Systematic observation revealed differences in response topography. In the delay component, subjects oriented more closely to the key and responses were less forceful compared with the no‐delay component. Our results give further evidence that preference and resistance to change covary within subjects. However, they challenge the premise that the critical determiners of preference (i.e., terminal‐link value) and resistance to change (behavioral mass) may be quantified purely in terms of stimulus—reinforcer relations.
BEHAVIORAL MOMENTUM: THE EFFECTS OF THE TEMPORAL SEPARATION OF RATES OF REINFORCEMENT
Authors: Cohen Steven L.
Published: March 2006

In Part 1 of the experiment, rats responded under a variable‐interval (VI) 30‐s schedule and a VI 120‐s schedule, with each in effect for a block of consecutive sessions. That is, the two VI schedules were presented in successive conditions. In Part 2 the VI schedules alternated each day, and in Part 3 the schedules alternated within the session as a multiple schedule. For half of the rats in Parts 1 and 2, the VI schedule alternated every few minutes within the session with a stimulus that signaled extinction. For each part, once response rates had stabilized, resistance to change was measured by prefeeding and extinction. When the schedules were examined in successive conditions (Part 1), resistance to extinction was greater under the VI 120‐s schedule of reinforcement than under the VI 30‐s schedule, but no consistent differences in resistance to prefeeding were observed between the two VI schedules. When the VI schedules alternated each day (Part 2), resistance to extinction was greater under the VI 120‐s schedule. However, no consistent differences in resistance to prefeeding were observed between the VI schedules without extinction in Group A, but resistance to prefeeding was greater under the VI 30‐s schedule for rats with the added extinction component in Group B. When the VI schedules alternated within the session as a multiple schedule (Part 3), resistance to extinction and resistance to prefeeding were greater under the VI 30‐s schedule. The data suggest that different rates of reinforcement, and their accompanying discriminative stimuli, must be compared within the same session (or at least on alternate days) to produce data consistent with the behavioral momentum model.
FOOD‐DEPRIVATION LEVEL ALTERS THE EFFECTS OF MORPHINE ON PIGEONS' KEY PECKING
Authors: Odum Amy L. , Haworth Stephen C. , Schaal David W.
Published: March 2006

Four pigeons pecked response keys under a multiple fixed‐ratio 30 fixed‐interval 5‐min schedule of food presentation. Components alternated separated by 15‐s timeouts; each was presented six times. Pigeons were maintained at 70%, 85%, and greater than 90% of their free‐feeding weights across experimental conditions. When response rates were stable, the effects of morphine (0.56 to 10.0 mg/kg) and saline were investigated. Morphine reduced response rates in a dose‐dependent manner under the fixed‐ratio schedule and at high doses under the fixed‐interval schedule. In some cases, low doses of morphine increased rates under the fixed‐interval schedule. When pigeons were less food deprived, reductions in pecking rates occurred at lower doses under both schedules for 3 of 4 birds compared to when they were more food deprived. When pigeons were more food deprived, low doses of morphine increased rates of pecking in the initial portions of fixed intervals by a greater magnitude. Thus, food‐deprivation levels altered both the rate‐decreasing and rate‐increasing effects of morphine. These effects may share a common mechanism with increased locomotor activity produced by drugs and with increased drug self‐administration under conditions of more severe food deprivation.
BEHAVIOR ANALYSIS AND DECISION MAKING
Authors: Fantino Edmund
Published: March 2006

Behavior analysts have developed powerful methodologies to assess central phenomena in areas that have been dominated by cognitive psychologists. Advances in instructional control, stimulus equivalence, choice, rule‐governed behavior, matching to sample, and verbal behavior are some of the tools that have been developed in the experimental analysis of behavior. Although the article focuses on the experimental analysis of reasoning, this is but one of the areas in which behavior analysts should have a greater impact on contemporary psychology.
PATCH CHOICE AS A FUNCTION OF PROCUREMENT COST AND ENCOUNTER RATE
Authors: Collier George , Johnson Deanne F. , Berman Justin
Published: March 2006

The effects of patch encounter rate on patch choice and meal patterns were studied in rats foraging in a laboratory environment offering two patch types that were encountered sequentially and randomly. The cost of procuring access to one patch was greater than the other. Patches were either encountered equally often or the high‐cost patch was encountered more frequently. As expected, rats exploited the low‐cost patch on almost 100% of encounters and exploited the high‐cost patch on a percentage of encounters that was inversely proportional to its cost. Meal size was the same at both patches. Surprisingly, when low‐cost patches were rare, the rats did not increase their use of high‐cost patches. This resulted in spending more time and energy searching for patches and a higher average cost per meal. The rats responded to this increased cost by reducing the frequency and increasing the size of meals at both patches and thereby limited total daily foraging cost and conserved total intake.
EFFECTS OF REINFORCEMENT RATE AND DELAY ON THE ACQUISITION OF LEVER PRESSING BY RATS
Authors: Bruner Carlos A. , Raul Avila S. , Acuña Laura , Gallardo Luis M.
Published: March 2006

The acquisition of lever pressing by naive rats, in the absence of shaping, was studied as a function of different rates and unsignaled delays of reinforcement. Groups of 3 rats were each exposed to tandem schedules that differed in either the first or the second component. First‐component schedules were either continuous reinforcement or random‐interval 15, 30, 60, or 120 s; second‐component schedules were fixed‐time 0, 1, 3, 6, 12, or 24 s. Rate of responding was low under continuous immediate reinforcement and higher under random‐interval 15 s. Random interval 30‐s and 60‐s schedules produced lower rates that were similar to each other. Random‐interval 120 s controlled the lowest rate in the immediate‐reinforcement condition. Adding a constant 12‐s delay to each of the first‐component schedule parameters controlled lower response rates that did not vary systematically with reinforcement rate. The continuous and random‐interval 60‐s schedules of immediate reinforcement controlled higher global and first‐component response rates than did the same schedules combined with longer delays, and first‐component rates showed some graded effects of delay duration. In addition, the same schedules controlled higher second‐component response rates in combination with a 1‐s delay than in combination with longer delays. These results were related to those from previous studies on acquisition with delayed reinforcement as well as to those from similar reinforcement procedures used during steady‐state responding.
REINFORCER EFFICACY IN A DELAYED MATCHING‐TO‐SAMPLE TASK
Authors: Weavers Richard , Foster T. Mary , Temple William
Published: March 2006

Five domestic hens were exposed to a delayed matching‐to‐sample task. Conditions 1, 5, and 8 were variable‐delay conditions in which five delays (0.25, 1, 2, 4, and 8 s) from the red or green sample to the presentation of the red and green comparison stimuli were presented a number of times during each session. In the fixed‐delay condition (Condition 3), each delay was presented for 15 sessions under a Latin square design across birds. When improvements in accuracy across the variable‐delay conditions are taken into account, the data were similar under both the variable and fixed delays. In Conditions 2, 4, 6, and 7 sample—reinforcer intervals were held at 8, 8, 4, and 2 s, respectively, while sample—choice intervals were varied within these during each session. With increasing sample—reinforcer interval, both initial discriminability (i.e., with sample—choice delay = 0) and rate of decrement in discriminability decreased. Although the former would be predicted if accuracy depends of the average sample—reinforcer interval, the latter would not. These data show that increasing the sample—choice interval had less effect on matching accuracy than increasing the sample‐reinforcer interval did.
HUMANS' CHOICE IN A SELF‐CONTROL CHOICE SITUATION: SENSITIVITY TO REINFORCER AMOUNT, REINFORCER DELAY, AND OVERALL REINFORCEMENT DENSITY
Authors: Ito Masato , Nakamura Kiyoko
Published: March 2006

Human subjects were exposed to a concurrent‐chains schedule in which reinforcer amounts, delays, or both were varied in the terminal links, and consummatory responses were required to receive points that were later exchangeable for money. Two independent variable‐interval 30‐s schedules were in effect during the initial links, and delay periods were defined by fixed‐time schedules. In Experiment 1, subjects were exposed to three different pairs of reinforcer amounts and delays, and sensitivity to reinforcer amount and delay was determined based on the generalized matching law. The relative responding (choice) of most subjects was more sensitive to reinforcer amount than to reinforcer delay. In Experiment 2, subjects chose between immediate smaller reinforcers and delayed larger reinforcers in five conditions with and without timeout periods that followed a shorter delay, in which reinforcer amounts and delays were combined to make different predictions based on local reinforcement density (i.e., points per delay) or overall reinforcement density (i.e., points per total time). In most conditions, subjects' choices were qualitatively in accord with the predictions from the overall reinforcement density calculated by the ratio of reinforcer amount and total time. Therefore, the overall reinforcement density appears to influence the preference of humans in the present self‐control choice situation.
EFFECTS OF CONSEQUENCES OF ADVICE ON PATTERNS OF RULE CONTROL AND RULE CHOICE
Authors: Schmitt David R.
Published: March 2006

Rules in the form of advice can inaccurately state the effects of recommended responses by overstating or understating size of the consequences. Three experiments investigated the effects of such inaccuracies on patterns of rule control and rule choice with female college students. In Experiment 1, signaled accurate, overstated, or understated rules specified that a given number of points would be earned by pressing a designated key. For some subjects, rules specified a number of points to be gained; for other subjects, rules specified a number of points to be lost from an amount given earlier. Point totals stated in the inaccurate rules averaged 25% more (overstated) or 25% less (understated) than those received. When subjects could choose either the response specified in the rule or an alternative response that produced an unpredictable number of points, they showed greater sensitivity to the inaccuracy of overstated rules than understated rules. In trials at the end of the experiment in which subjects could choose which rule to see, subjects did not always choose accurate rules and often chose inaccurate rules for which they had shown less sensitivity earlier. Experiment 2 replicated this pattern in which subjects could choose which type of rule to see on a greater number of trials. Some evidence suggested that subjects prefer an improvement from the outcomes promised to those later received. In Experiment 3, rules misstated by averages of 25% and 50% were compared. Evidence suggested that increasing the size of the misstatement reduced the discrimination of inaccurate rules from accurate ones.