bluuebunny/crossref_metadata_2025 huggingface dataset:
HES1 Inhibits Cycling of Hematopoietic Progenitor Cells via DNA Binding
Authors: Yu Xiaobing , Alder Jonathan K. , Chun Jong Ho , Friedman Alan D. , Heimfeld Shelly , Cheng Linzhao , Civin Curt I.
Published: March 2006

Notch signaling is implicated in stem cell self-renewal, differentiation, and other developmental processes, and the Drosophila hairy and enhancer of split (HES) 1 basic helix-loop-helix protein is a major downstream effector in the Notch pathway. We found that HES1 was expressed at high levels in the hematopoietic stem cell (HSC)–enriched CD34+/[CD38/Lin]− /low subpopulation but at low levels in more mature progenitor cell populations. When CD34+ cells were cultured for 1 week, the level of HES1 remained high in the CD34+ subset that had remained quiescent during ex vivo culture but was reduced in CD34+ cells that had divided. To investigate the effects of HES1 in human and mouse hematopoietic stem–progenitor cells (HSPCs), we constructed conditional lentiviral vectors (lentivectors) to introduce transgenes encoding either wild-type HES1 or a mutant lacking the DNA-binding domain (ΔBHES1). We found that lentivector-mediated HES1 expression in CD34+ cells inhibited cell cycling in vitro and cell expansion in vivo, associated with upregulation of the cell cycle inhibitor p21cip1/Waf1 (p21). The HES1 DNA–binding domain was required for these actions. HES1 did not induce programmed cell death or alter differentiation in HSPCs, and while short-term repopulating activity was reduced in HES1-transduced mouse and human cells, long-term reconstituting HSC function was preserved. Our data characterize the complex, cell context–dependent actions of HES1 as a major downstream Notch signaling regulator of HSPC function.
EFFECTS OF EFFORT ON RESPONSE RATE1
Authors: Chung Shin‐Ho
Published: March 2006

Pigeons were trained to peck for food reinforcement, and the minimum effective force for a peck was varied. In a single‐key situation, the response rate was unaffected up to a certain force value, beyond which increments caused a proportional decrement in response rate. Transient enhancement and suppression effects were observed following a change in the force requirement. A change from a high force requirement to a low force requirement resulted in a temporary enhancement of response rate above the stable performance level, whereas a change from a low to a high requirement produced a temporary suppression of the rate below the stable rate. In a two‐key situation, the response rate on a key with a given force remained unaffected by the force requirement on the other key. When the rate of response was plotted against the required force, the resultant function was remarkably similar to that obtained from the single‐key experiment. When the rates of reinforcement on the two keys differed, the decrement in response rate produced by an increase in the force requirement was proportionally greater on the key with the lower rate of reinforcement.
STRESS‐INDUCED BREAKDOWN OF AN APPETITIVE DISCRIMINATION1
Authors: Hearst Eliot
Published: March 2006

Rats trained to discriminate between SD and SΔ for food reinforcement showed marked impairments in this discrimination when strong, unavoidable shocks occurred at the termination of a third stimulus. The predominant feature of this impairment was a supernormal rate of unreinforced (SΔ) behavior. Shocks delivered without exteroceptive warning also led to a discriminative breakdown. The effect was a direct function of shock intensity. When behavior was strongly suppressed in the third stimulus by response‐correlated shock (“punishment”), instead of unavoidable shock, breakdowns were only temporary; as soon as responding recovered from its overall suppression, discriminative performance returned to normal. The discriminative deterioration may be interpreted as an emotional by‐product of frequent aversive stimulation, but accidental contingencies could also have played a role.
INTEROCULAR TRANSFER OF DISCRIMINATIONS IN THE PIGEON1
Authors: Catania A. Charles
Published: March 2006

Pigeons with one eye covered were trained to discriminate intensities or colors of stimuli located to one side of the head, or intensities, colors or forms of stimuli located in front of the beak. Each discrimination transferred to the covered eye, even when previous training with the covered eye included the reversal of the tested discrimination. Pigeons also were able to learn conditional discriminations in which appropriate responding depended on which eye was covered.
A FORTY‐THREE DAY AVOIDANCE SESSION1
Authors: Ulrich Roger E. , Brierton Gary R. , Mabry John H. , Stachnik Thomas J.
Published: March 2006

A single Sprague‐Dawley rat was subjected to an extended discriminated avoidance session in effect continuously for over 1000 hr (43 days). The longest possible shock‐free interval that the subject could obtain without responding was 5 min. Since the subject did not sleep through shock, all resting or sleeping was interrupted at least once every 5 min by either a response or a shock. Neither the experimental (avoidance) animal nor a second animal which received all shocks not avoided by the first, gave any appearance of ill effects from the protracted session.
TEMPORAL ALTERNATION IN THE WHITE RAT?
Authors: Keehn J. D.
Published: March 2006

Four white rats were reinforced after 15 then 45 then 15 then 135 (or 5) responses to a bar under a single exteroceptive stimulus condition. Three came to make long pauses before the longest ratio in the schedule but not before any of the others. Four other rats were reinforced after alternate response chains each made on two bars. The first chain was FR5FR5 for all subjects, the second FR5FR40 for two, and FR40FR5 and FR20FR5 for one subject each. Subjects reinforced on schedule mix (chain FR5FR5 chain FR5FR40) both paused longer after the first than after the second chain relatively early in training. Later, the subject reinforced on mix (chain FR5FR5 chain FR40FR5) also paused longer after the first chain, but pauses of the fourth subject were equally short after both chains. When the ratios in the second chain were reversed the two subjects now reinforced on mix (chain FR5FR5 chain FR40FR5) paused much longer after the first chain, but the other two paused only slightly longer after the first than after the second chain.
DEVELOPMENT OF BEHAVIORAL COMPENSATION TO THE EFFECTS OF SCOPOLAMINE DURING FIXED‐INTERVAL REINFORCEMENT1
Authors: Charney Nicolas H. , Reynolds G. S.
Published: March 2006

Rats were injected with scopolamine before every daily session of water reinforcement on a fixed‐interval (FI) schedule. Initially the drug decreased the rate of responding. Control injections of scopolamine following each session did not. Over 119 sessions, the typical FI performance developed more slowly in the animals drugged before the sessions. Their rates of responding increased from session to session, to a level slightly greater than that of the animals drugged after the sessions. Their rates did not increase. The effects of injections before the session were not duplicated by increasing the deprivation of animals drugged after the session.
PUNISHMENT BY SD ASSOCIATED WITH FIXED‐RATIO REINFORCEMENT1
Authors: Thompson Donald M.
Published: March 2006

Two pigeons were trained with positive reinforcement on a multiple FR VI 2 schedule. The VI 2 component was held constant while the FR component was changed from ratios of 1 to 300. After responding had stabilized at each FR value, VI responses produced briefly either the fixed‐ratio SD or a stimulus uncorrected with either schedule component. Compared to the effects of the uncorrected stimulus change, the fixed‐ratio SD produced a decrease in VI responding proportional to the size of the FR requirement. It is concluded that stimuli associated with high FR schedules served as punishment for the ongoing behavior.
RELATIVE RATE OF RESPONSE AND RELATIVE MAGNITUDE OF REINFORCEMENT IN MULTIPLE SCHEDULES1
Authors: Shettleworth Sara , Nevin John A.
Published: March 2006

Pigeons were trained on a multiple schedule in which the duration of access to grain reinforcement was varied independently in the two components. The relative response rate in one component was an increasing function of the relative duration of reinforcement in that component. The similarity of this interaction to that found in multiple schedules of different reinforcement frequency is discussed. Extinction data were also similar to those obtained after training on multiple schedules of different reinforcement frequency.
MODIFICATION OF OBSERVING BEHAVIOR1
Authors: Dardano J. F.
Published: March 2006

The effects on monitoring performance of a limited hold (LH) terminated by a bell or by electric shock and of periodic rest periods were investigated. The sensitivity of basal skin conductance to different monitoring conditions was also studied. Humans monitored a visual display in several 2‐hr sessions under the Holland procedure. In each session, signals were programmed by one of the following three multiple schedules: a variable interval of 6 min (VI 6) and a VI 6 with a limited hold (LH) terminated by a bell; a VI 6 and a VI 6 LH terminated by electric shock; a VI 6 LH terminated by shock and a time‐out (TO). The two components of each schedule alternated at 15‐min intervals. The average observing response rate of eight subjects was lowest during the VI 6 periods, higher in periods when the LH was terminated by a bell, and highest when the LH was terminated by shock. Periodic TO periods did not appreciably increase the response rate under the VI 6 LH shock component. A differential level of palmar skin conductance under the two components of a schedule was present only under the mult VI 6 LH shock‐TO.
DIFFERENTIATION OF A PRECISE TIMING RESPONSE1
Authors: McMillan D. E. , Patton R. A.
Published: March 2006

Humans, monkeys, and rats were trained by a process of successive differentiations to press a bar for at least 1.00 sec but for no longer than 1.27 sec. Initially, animals were reinforced for all responses, then a minimum duration of response was gradually differentiated, below which no responses were reinforced. Finally, a maximum duration of response was differentiated above which no responses were reinforced. The duration of response in all three species approximated the minimum duration of response necessary for reinforcement. As the duration of response necessary for reinforcement increased, so did the mean duration of response in the three species. As the maximum allowable duration decreased, further compression of the mean occurred. The fact that the acquisition of the differentiation was approximately the same in all three species is a further indication of the control reinforcement exerts on operant responding.
VARIABLES DETERMINING THE EFFECTS OF DELAY IN REINFORCEMENT1,2
Authors: Ferster C. B. , Hammer Clifford
Published: March 2006

Procedures were discovered for maintaining a small fixed‐ratio performance under 24‐hr delay in reinforcement, by appropriate manipulation of the length of delay, amount of food delivered, and size of the fixed ratio. Other experiments showed that (1) the parameters discovered in the first experiment could produce the same result without the complex history of the first procedures; (2) the same parameters of the delayed‐reinforcement procedure could maintain an explicit chain of responses; (3) gradual increase in the delay in reinforcement from small to large values was not a necessary condition for achieving the major result, if large amounts of food were delivered as reinforcement and all of the behaviors were first under good control of the relevant stimuli with short delays.
SEQUENTIAL RESPONSE EFFECTS IN THE WHITE RAT DURING CONDITIONING AND EXTINCTION ON A DRL SCHEDULE1,2
Authors: Ferraro D. P. , Schoenfeld W. N. , Snapper A. G.
Published: March 2006

Sequential IRT data were obtained for three rats on a DRL 60‐sec reinforcement schedule. It was found that first‐order sequential dependencies exist under this schedule, including the partial dependence of the length of any given IRT on the length of the preceding IRT. The sequential analysis also served to extend the finding in the literature, based on frequency distributions, that the likelihood of a reinforced IRT is greater after a reinforced IRT than a non‐reinforced IRT. Rapid extinction and reconditioning were obtained.
CONDITIONED PUNISHMENT1
Authors: Hake D. F. , Azrin N. H.
Published: March 2006

Responses of pigeons were maintained by a VI schedule of food reinforcement. Conditioned punishment was programmed by having these responses concurrently produce an originally neutral stimulus. The effectiveness of this response‐contingent stimulus was maintained by infrequent and prearranged stimulus‐shock pairings delivered independently of responses. This conditioned punishment procedure reduced the overall response rate as long as the procedure was in effect. The extent and durability of the reduction was a function of the intensity of the shock that was paired with the stimulus. Analysis of the reduction in the overall response rate revealed: (1) a reduction of responses occurring in the absence of the response‐contingent stimulus, which was designated as a “punishing” effect, and (2) a reduction of responses during the response‐contingent stimulus, which was designated as a “suppressive” effect.
MOTIVATIONAL ASPECTS OF ESCAPE FROM PUNISHMENT1
Authors: Azrin N. H. , Hake D. F. , Holz W. C. , Hutchinson R. R.
Published: March 2006

Punishment and escape were studied simultaneously by allowing a subject to escape from a stimulus situation in which responses were punished, into a stimulus situation in which responses were not punished. The frequency of the punished responses was found to be an inverse function of the intensity of punishment, whereas the frequency of the escape response was a direct function of the intensity of punishment. Both of these functions were obtained under three different schedules of food reinforcement. The strength of the escape behavior was evidenced by (1) the emergence of the escape response even when the frequency of food reinforcement decreased as a consequence of the escape response, (2) the maintenance of the escape response by fixed‐interval and fixed‐ratio schedules of escape reinforcement, and (3) the occurrence of escape responses at intensities of punishment that otherwise produced only mild suppression of the punished response when no escape was possible. This last finding indicates that a subject may be driven out of a situation involving punishment even though the punishment is relatively ineffective in suppressing the punished responses when no escape is possible.
CLASSICAL CONDITIONING OF AGGRESSIVE DISPLAY IN SIAMESE FIGHTING FISH1
Authors: Thompson Travis , Sturm Thomas
Published: March 2006

Unconditioned aggressive‐display behavior elicited by the mirror image of a male Siamese Fighting Fish was brought under the control of a previously ineffective stimulus by classical conditioning. A stimulus light repeatedly paired with mirror presentation came to elicit the complex aggressive‐behavior sequence. Relative rates of acquisition of four components of the display were compared. Fin erection and undulating movements were acquired most rapidly while gill‐cover erection and frontal approach were acquired most slowly. A discriminative conditioning procedure revealed that the response was specifically elicited by the conditioned stimulus, and not a sensitization artifact.
EFFECTS OF DELAYED REINFORCEMENT IN A CONCURRENT SITUATION1
Authors: Chung Shin‐Ho
Published: March 2006

Pigeons were trained to peck either of two response keys for food reinforcement on equated aperiodic schedules. Delays of reinforcement for pecks at one key reduced the relative frequency of pecking exponentially as a function of the delay interval. Similar functions were obtained when other dependent variables were plotted against the delay interval.
ELICITATION OF AGGRESSION BY A PHYSICAL BLOW1
Authors: Azrin N. H. , Hake D. F. , Hutchinson R. R.
Published: March 2006

Squirrel monkeys were exposed to brief tail‐pinches in the presence of a cloth‐covered ball. Attack was elicited against the ball as a direct function of the force of the tail‐pinch. This finding in conjunction with previous findings regarding electric shock and intense heat demonstrates that several types of aversive stimulation can elicit aggression.
PLOTTING AND ANALYZING CUMULATIVE RESPONSE CURVES IN OPERANT CONDITIONING STUDIES1
Authors: Herrick Robert M.
Published: March 2006

Because the response and time scales used in plotting cumulative response curves are often poorly selected, ineffective displays often result. The visual cue of a response rate change is the difference, Δθ, between the angles, θ1 and θ2, representing the two rates, R1 and R2. These variables are related by: tan θ2 = R2/R1 tan θ1. For a given rate change, the value of θ1, namely, Mθ1, that yields the maximum value of Δθ, namely, Δθmax, is given by Mθ1 = arc sin. Ideally, the initial response rate should be represented by the Mθ1 appropriate for a given rate change. Because of practical considerations, however, some compromises with the ideal are allowable. Included in the discussion are (a) steps required to select appropriate response and time scales, with examples, and (b) guideposts for evaluating rate changes by means of angular changes.
BRAIN STIMULATION AS A REINFORCER: INTERMITTENT SCHEDULES1
Authors: Pliskoff Stanley S. , Wright James E. , Hawkins T. Daryl
Published: March 2006

Rats with chronically implanted, bipolar electrodes in the septal and medial forebrain bundle areas, in addition to the region of the mammillary bodies of the posterior hypothalamus, were trained to press a permanently mounted lever in order to produce a second, retractable lever. Rewarding brain stimulation was programmed on the retractable lever; following completion of the programmed number of CRF response‐stimulations, that lever was retracted from the box. Responding on the permanent lever could reintroduce the retractable lever. Fixed interval, fixed ratio, DRL, and variable interval schedules were programmed on the permanent lever in the range of schedule parameters often used with conventional reinforcers. Typical effects are described, and it is concluded that there are no striking differences between brain‐stimulation reinforcement and the conventional reinforcers.
STIMULUS ASPECTS OF AVERSIVE CONTROLS: THE EFFECTS OF RESPONSE CONTINGENT SHOCK1
Authors: Hoffman Howard S. , Fleshler Morton
Published: March 2006

A tone ending with electrical shock was periodically presented to pigeons while they pecked a key for food. Pairs of birds were run simultaneously under a yoked program which insured that both birds received the same number and temporal distribution of shocks. For one of the birds, shock was always initiated by a peck; for the other, shock was unavoidable. Both procedures led to reduced rates of pecking in the presence of the tone, and gradients of stimulus generalization were obtained. But the effects of response contingent shock extinguished more rapidly than the effects of unavoidable shock. In general, birds exposed to unavoidable shock tended to respond at intermediate rates throughout tone, whereas those exposed to response contingent shock ceased to peck for part or all of the tone period.
SOME SEQUENTIAL ASPECTS OF IRTs EMITTED DURING SIDMAN‐AVOIDANCE BEHAVIOR IN THE WHITE RAT1,2
Authors: Wertheim George A.
Published: March 2006

This study investigated some of the serial patterns among interresponse times during Sidman avoidance. It was found that the momentary probability of a response was determined by the length of exposure to the avoidance procedure during a session, by the time since the last shock, and by the duration of the preceding IRT.
SOME DISCRIMINATIVE PROPERTIES OF FIXED RATIO PERFORMANCE IN THE PIGEON1
Authors: Pliskoff Stanley S. , Goldiamond Israel
Published: March 2006

The discriminative control over a spatial choice response exercised by prior behavior was studied using a procedure involving discrete exposures to a two‐member chained schedule. The initial member (red key) was either a smaller or larger fixed ratio (Mix FR:FR), the completion of which produced, after a 1‐sec delay, two white response keys. If the larger FR had been completed as the initial chain member, a single peck on the right white key was reinforced; after the smaller FR, a peck on the left white key was reinforced. Frequencies of unreinforced responses (SΔ responses) were determined with several pairs of red‐key FRs: 95‐5, 75‐25, 65‐35, 60‐40, 58‐42 and 50‐50. The SΔ response frequencies were low through the FR pair 65‐35; sharp increases were obtained with pairs 60‐40 and 58‐42. Later, curves analogous to stimulus generalization functions were obtained using a probe procedure. Finally, the delay interval between completion of a red‐key FR and the white‐key choice response was manipulated: results were variable, but SΔ response frequencies tended to increase with increasing delays.
FIXED RATIO AND EXTINCTION PERFORMANCE OF INFANTS IN THE SECOND YEAR OF LIFE1,2
Authors: Weisberg Paul , Fink Edward
Published: March 2006

Five 14½‐ to 19½‐month‐old infants were trained to lever press for snacks on small fixed ratio schedules of reinforcement. Within four to nine sessions, responding under FR 10 was established for four subjects and FR 15 for the other. Each subject's last session revealed behavioral patterns similar to animal and human FR trained subjects—a high and constant ratio rate, mixed with a zero rate following reinforcements. Deviations were mostly in the form of prolonged and variable post‐reinforcement pauses. These and other irregularities were probably due to the limited deprivation conditions and improper training procedures in which the ratio (for two subjects) was ascended too early and too quickly. Extinction was instituted during the last session. The degree to which extinction performance matched that of other organisms depended upon how stable and “ratio‐like” performance was during conditioning.
ANALYSIS OF WATER AND NaCl SOLUTION ACCEPTANCE BY SCHEDULE‐INDUCED POLYDIPSIA1
Authors: Falk John L.
Published: March 2006

Animals were trained on a VI 1‐min schedule for food pellets, and concurrent water intake was measured. The polydipsia induced was analyzed in terms of the frequency distribution of post‐pellet licking burst sizes and the trend of polydipsia throughout the session. An ascending series of NaCl solutions was presented consecutively over daily sessions and a typical NaCl acceptance‐rejection intake function was generated. Beginning in the 0.9‐1.2% NaCl range, the animals drank less often during the session but took larger drinks when they did drink. Neither the frequency of drinks nor the mean licking burst size were simply related to the volumes of NaCl solution consumed. The NaCl acceptance‐rejection function cannot be explained in terms of water repletion factors alone.
OPERANT BEHAVIOR AND THE GALVANIC SKIN POTENTIAL UNDER DRL SCHEDULE1
Authors: Meurice Emile , Weiner Harold , Sloboda Walter
Published: March 2006

Motor and galvanic skin potential (GSP) activity were investigated during the conditioning, extinction, and reconditioning of motor responses under a differential reinforcement of low rate (DRL) schedule of reinforcement. Interresponse time (IRT) distributions for motor responses during conditioning and reconditioning gradually stabilized at a peak just beyond the minimal IRT required for reinforcement. Few unreinforced motor responses and “bursts” of motor responses were observed during conditioning and reconditioning. Relative to conditioning and reconditioning, extinction effected larger IRTs and smaller GSP amplitudes. GSP amplitudes were greater for unreinforced than for reinforced motor responses during conditioning and reconditioning. However, GSP amplitudes associated with the unreinforced extinction responses were smaller than either the reinforced or unreinforced responses during conditioning and reconditioning.
AUDITORY REACTION TIME AND THE DERIVATION OF EQUAL LOUDNESS CONTOURS FOR THE MONKEY1
Authors: Stebbins William C.
Published: March 2006

Monkeys were trained to release a telegraph key at the onset of a pure tone. Latency of the response was measured over a 70‐db range of sound pressure (re 0.0002 dyn/cm2) at six frequencies (250 to 15,000 cps). Latency was found to be an inverse exponential function of intensity at all frequencies. Equal loudness was inferred from the equal latency contours which were constructed from the latency‐intensity functions at each frequency. These data indicate peak auditory sensitivity for the monkey near 1000 cps. At the frequencies above and below 1000 cps consistently more sound energy was required for equal latency.
THE EFFECT OF MULTIPLE SΔ PERIODS ON RESPONDING ON A FIXED‐INTERVAL SCHEDULE: IV. EFFECT OF CONTINUOUS SΔ WITH ONLY SHORT SD PROBES1
Authors: Dews P. B.
Published: March 2006

Pigeons were studied under FI 500 sec in which an SΔ was present throughout the interval except during the terminal 50‐sec segment and one earlier 50‐sec segment. Very little responding occurred during the presence of SΔ. The rate of responding in the earlier 50‐sec SD segments was lower than in the terminal SD segment. There was a clear trend for the rate of responding in the earlier SD segment to be progressively higher the later it occurred in the course of the FI 500 sec. This trend was shown roughly to parallel the increasing rate of responding in a conventional FI 500 sec with no interruption by SΔ. Since the changing tendency to respond through the FI survives massive disruption by SΔ, it is concluded that the control of responding through the FI does not require continuous mediating behavior. It is suggested that it is the decaying retroactive influence of the reinforcer on responses that occurred longer and longer before the reinforcer occurred which produces the familiar scalloped pattern of responding under FI schedules.
EXTINCTION‐INDUCED AGGRESSION1
Authors: Azrin N. H. , Hutchinson R. R. , Hake D. F.
Published: March 2006

Pigeons were conditioned to peck a response key under a procedure that alternated periods of food reinforcement with periods of extinction. The pigeons attacked a nearby pigeon at the onset of extinction. Some also attacked a stuffed model of a pigeon. The duration of attack was an inverse function of the time since the last food reinforcement and a direct function of the number of reinforcements. The pigeons attacked after the last food delivery whether or not the conditioned pecking response was required and whether or not the extinction period was signaled. The food had to be eaten; the mere sight and sound of food being delivered did not produce attack. Prior satiation reduced attack. The phenomenon was not attributable to a past history of competition between pigeons since socially deprived pigeons also attacked. Superstitious reinforcement of attack was not found to be a factor. The results indicated that the transition from food reinforcement to extinction was an aversive event that produced aggression.
DISCRIMINATIVE AND REINFORCING PROPERTIES OF TWO TYPES OF FOOD PELLETS1
Authors: Cruse Daniel B. , Vitulli William , Dertke Max
Published: March 2006

In Experiment I some discriminative functions of food pellets were studied by developing a multiple schedule of reinforcement (mult FR 30 FI 3) in which the delivery of a standard laboratory food pellet as a reinforcer set the occasion for reinforcement on every 30th response (FR 30), and the delivery of a sucrose food pellet as a reinforcer set the occasion for reinforcement after a 3‐min interval (FI 3). Discriminative stimulus control by the type of pellet was also demonstrated by reversing the operant discrimination and having the standard pellet control the FI 3 and the sucrose pellet control the FR 30. In Experiment II a mult FR 30 FR 30 with two bars was developed; a standard food pellet was followed by an FR 30 on Bar 1 and extinction (ext) on Bar 2, while a sucrose pellet was followed by an FR 30 on Bar 2 and ext on Bar 1. A control rat was placed, for comparison, on a mixed (mix) FR 30 FR 30 schedule with two bars, but neither bar correlated with the type of food pellet. In Experiments I and II the similarity between pellet controlled multiple schedules and multiple primed schedules was discussed, as was the comparability of transitions and effectiveness of control between pellet controlled multiple schedules and multiple schedules providing continuous exteroceptive stimuli.
THE STABILITY AND CONTROL OF CONDITIONED NOISE AVERSION IN THE TILT CAGE1
Authors: Halpern Mimi , Lyon Melvin
Published: March 2006

Twenty‐six rats were used to study the development of stable conditioned responding to terminate white noise (100 or 105 db) in a tilt cage apparatus. Preliminary work, with one end of the cage consistently associated with silence, demonstrated stability at a high level of cumulative noise‐off time per session. Time spent at the noise‐off cage end was unaffected by lay‐off and showed adaptation to reversal of the cage end functions. Variability in reversal acquisition, insensitivity to stimulus intensity changes and persistence in remaining at one end of the cage in the absence of noise‐termination contingencies indicated the need for more precise behavioral control. A schedule programming several reversals of the no‐noise end at variable intervals within each session was developed. Performance on the latter schedule was characterized by stability of high noise‐off times and also proved more sensitive than the preliminary method to stimulus intensity changes (55, 70, 100 db) as measured by both cumulated noise‐off time and cage crossing rates. The ease of training combined with sensitivity to stimulus change and the lack of highly specific motor response requirements make this technique promising for use with animals potentially debilitated by drugs or surgical aftereffects.
VARYING TEMPORAL PLACEMENT OF AN ADDED STIMULUS IN A FIXED‐INTERVAL SCHEDULE1
Authors: Farmer John , Schoenfeld W. N.
Published: March 2006

One paradigm for exploring stimulus effects on behavior is defined for steady state experiments. The paradigm is illustrated by a 60‐sec fixed‐interval reinforcement schedule wherein a 6‐sec light is introduced into each interval. The temporal relation of this stimulus to the reinforcer is the independent variable that is systematically explored. Two experiments studied this temporal relation under two parametric conditions: (a) when the 6‐sec light occurs once in each 60‐sec interval, (b) when the 6‐sec light occurs twice in each interval, the second time always during the 6 sec immediately preceding the reinforcer. Functions are presented showing the effect of the 6‐sec light on responding at all points in the fixed‐interval.
SCHEDULE‐INDUCED POLYDIPSIA AS A FUNCTION OF FIXED INTERVAL LENGTH1
Authors: Falk John L.
Published: March 2006

Rats were trained to bar‐press for Noyes pellets on an FI schedule which was increased serially through several values from 2 sec to as high as 300 sec. Concurrently, water was freely available. As FI length was increased, the degree of polydipsia increased linearly to a maximum value.
SOME EFFECTS OF METHYLPHENIDATE ON STIMULUS CONTROL OF RATIO AVOIDANCE BEHAVIOR IN THE RAT1
Authors: Stretch Roger , Blackman Derek , Alexander Daphne
Published: March 2006

After exposure to an avoidance schedule which included a warning signal, a rat was placed on a multiple schedule in which the first component was the same as before, i.e., a single response reset the response‐shock interval, delaying shock, and the second component differed only in that four bar‐presses were required to postpone shock. A fixed ratio requirement of four responses (FR 4) generated behavior resembling a fixed ratio requirement of one response (FR 1) since responding was controlled by the warning signal but more shocks were received. At a dosage of 2 mg/kg, methylphenidate given intraperitoneally decreased shock frequency during FR 4 periods while FR 1 behavior was not affected; at 4 mg/kg, stimulus control of avoidance responding was impaired during both components. Results at 4 mg/kg were partially confirmed by two animals exposed to an FR 4 avoidance schedule which included a warning signal but with different parameters. Response distributions showed that methylphenidate increased response rates in the absence of the warning signal, i.e., stimulus control of ratio‐avoidance behavior was impaired although the increased response rates reduced shock frequency. One hour later responses again occurred more frequently during the signal than in its absence but shocks were less frequent than during control (non‐drug) periods.
AVOIDANCE OF A RETURN TO THE FIRST COMPONENT OF A CHAIN FROM THE TERMINAL COMPONENT1
Authors: Thomas John R.
Published: March 2006

Three pigeons were trained on a chained fixed interval‐fixed ratio schedule. Avoidance behavior which postponed a return to the first chain component from the second component was maintained on a second response key concurrently with the second component. When the fixed interval length was increased, avoidance rates first increased and then decreased as a function of fixed interval length. As the fixed ratio requirement was increased for one subject, avoidance rates first declined and then increased at larger fixed ratio values. Avoidance behavior maintained by postponing the first chain component was similar to avoidance behavior maintained by postponing a time out period.
CONDITIONED REINFORCEMENT IN SECOND‐ORDER SCHEDULES1
Authors: Kelleher Roger T.
Published: March 2006

Pigeons responded under a schedule in which food was presented only after a fixed number of fixed‐interval components were completed. Two such second‐order schedules were studied: under one, 30 consecutive 2‐min fixed‐interval components were required; under the other, 15 consecutive 4‐min fixed‐interval components were required. Under both schedules, when a 0.7‐sec stimulus light was presented at completion of each fixed interval, positively accelerated responding developed in each component. When no stimulus change occurred at completion of each fixed interval, relatively low and constant rates of responding prevailed in each component; a similar result was obtained when a 0.7‐sec stimulus change occurred at completion of each fixed interval except the one which terminated with primary reinforcement. The 0.7‐sec stimulus correlated with food delivery was an effective conditioned reinforcer in maintaining patterns of responding in fixed‐interval components despite low average frequencies of food reinforcement.
A COMPARISON OF TWO PSYCHOPHYSICAL METHODS USING ANIMALS1
Authors: Moskowitz Herbert , Kitzes Leonard
Published: March 2006

A discrimination box containing two levers with a light above each was used to train eight rats to press beneath the brighter light for a milk reinforcer. The brighter light was held constant and the comparison light was varied to produce 12 brightness differences. The animals were run under two experimental methods: the block method in which each brightness level comparison was presented for a block of 11 contiguous trials, and the staircase method in which the sequence of brightness comparisons was determined by the correctness of the response on the preceding comparison. The block method produced a smaller differential brightness threshold and a larger change in discrimination performance for stimulus magnitude changes than did the staircase method.
VARIABLE‐INTERVAL PUNISHMENT DURING VARIABLE‐INTERVAL REINFORCEMENT1
Authors: Filby Yasuko , Appel James B.
Published: March 2006

Variable‐interval punishment was superimposed on a variable‐interval food reinforcement baseline for three groups of rats. The value for the variable‐interval punishment schedule was the same as that for the variable‐interval food reinforcement schedule, although the two schedules were programmed independently. The three groups were Variable Intervals 0.5, 1, and 3 min. Little or no suppression occurred in the three groups at mild (0.2 and 0.4 ma) intensities of punishment, but at 0.6 ma, complete suppression occurred almost uniformly. During continued punishment, there was no consistent recovery toward the pre‐punishment baseline at suppressing intensities of punishment. After punishment was discontinued, recovery from suppression was more rapid the lower the punishment intensity, and the lower the value of the variable‐interval schedules of reinforcement and punishment.
A CONDITIONED REINFORCER MAINTAINED BY TEMPORAL ASSOCIATION WITH THE TERMINATION OF SHOCK
Authors: Dinsmoor James A. , Clayton Marilyn H.
Published: March 2006

Two experiments were conducted to determine whether a stimulus can be established as a positive conditioned reinforcer by associating it with the termination of shock, but without training the animal to make any response in its presence. In the first, six rats were conditioned to press a bar to terminate shock on a variable ratio schedule; white noise was then substituted as the immediate consequence, with the shock terminating 30 sec after the last press in its presence. It was found that the rate of pressing in the absence of noise depended on the contingency between the pressing and the noise. The second experiment sought to determine whether the difference in rates before and after the onset of the noise was due to the reinforcement of prior responding by the onset of the noise or to the suppression of subsequent responding by differential reinforcement of competing behavior. Six more rats were trained in the same manner, but with shock terminating 30 sec after the onset of the noise, regardless of what the animal did in its presence. Again the rate was higher before the onset of the noise, indicating that pressing was indeed maintained by the noise as a conditioned reinforcer.
INVESTIGATIONS OF A MIRROR‐IMAGE TRANSFER EFFECT IN PIGEONS1
Authors: Thomas David R. , Klipec William , Lyons Joseph
Published: March 2006

In two separate experiments, pigeons trained binocularly to peck a key on which an oblique line (e.g., 60° counter‐clockwise rotation from horizontal) was projected yielded bi‐modal angularity generalization gradients in extinction, with peaks of responding at both the training stimulus and its mirror image (in this case 120°). This mirror‐image transfer effect may be analogous to an “octave effect” in auditory generalization, but Mello's finding of a mirror‐image reversal transfer effect following monocular training in pigeons suggests an alternative interpretation.
A COMPUTER ANALYSIS OF SERIAL INTERACTIONS IN SPACED RESPONDING1
Authors: Weiss Bernard , Laties Victor G. , Siegel Louis , Goldstein David
Published: March 2006

Serial dependencies in inter response times were studied by means of a digital computer. In monkeys exposed to a DRL 20‐sec schedule of reinforcement, serial interactions appeared at all stages of training. Early in training the serial effects consisted of trains of relatively long interresponse times interspersed among trains of relatively short ones. Later on, the serial effects appeared to be characterized by a tendency to drift up and down in long wavelength periods around the minimum interval required for reinforcement. After training to a point at which most interresponse times produced reinforcement, serial effects of a still more subtle nature appeared. These effects were made apparent by autocorrelation and power spectrum methods and consisted of both long‐term and extremely short‐term fluctuations in interresponse times.
THE EFFECTS OF ELECTROCONVULSIVE SHOCK ON THE ACTION OF A REINFORCING STIMULUS1
Authors: Sprott Richard L. , Waller Marcus B.
Published: March 2006

Three experiments sought to evaluate the effect of electroconvulsive shock on the action of a reinforcing stimulus. In all experiments behavior was maintained on a 2 min variable interval schedule for food reinforcement. Foot shock at the termination of a buzzer stimulus served as the reinforcing stimulus for conditioned suppression during the ensuing buzzer interval. Omission of foot shock at the termination of the buzzer stimulus was followed by normal responding (no conditioned suppression) during the next buzzer interval. In Exp I electroconvulsive shock followed foot shock at varying time intervals. In the first subsidiary experiment electroconvulsive shock followed an unreinforced buzzer stimulus at varying time intervals. In the second subsidiary experiment electroconvulsive shock followed foot shock at varying time intervals and an additional buzzer stimulus was sounded between the termination of foot shock and the onset of electroconvulsive shock. These three experiments demonstrated that electroconvulsive shock invariably abolished the effects of the reinforcing stimulus if it followed conditioning by no more than 10.0 sec and never had an effect if it followed conditioning by 12.5 sec or more; electroconvulsive shock was not acting as a reinforcing stimulus in this situation.
AN EXPERIMENTAL SOCIAL RELATION BETWEEN TWO MONKEYS1
Authors: Boren John J.
Published: March 2006

A technique was developed for studying the reinforcement of one organism by another. Two pairs of monkeys served as subjects in adjoining but separate lever‐pressing chambers. However, they were in visual, aural, and tactile contact with each other. After both pairs were trained to tolerate delays of reinforcement and one pair was trained under stimulus control to exchange reinforcements, monkey A of each pair pressed a lever to feed monkey B, and monkey B pressed to feed monkey A. The experiment sought to determine if this social interaction could be maintained. With a free responding procedure where the monkeys could work at any time in any order, the social relation proved unstable. After several oscillations in which one monkey did most of the responding and the other monkey did most of the eating, the reinforcement frequency for both pairs of animals decreased to very low levels. The final outcome would have been starvation had the experimenter not intervened.
OPERANT REINFORCEMENT OF AN AUTONOMIC RESPONSE: TWO STUDIES
Authors: Gavalas Rochelle Johnson
Published: March 2006

Two successive studies were conducted to determine the possibility of operant reinforcement of nonspecific galvanic skin resistance responses. In the first study, with five experimental and three control subjects who served for 20 to 30 min a day for 10 days, all experimental subjects learned to emit more nonspecific galvanic skin resistance responses than their ad hoc matched controls. In a second study, nine experimental and nine control subjects were matched for first‐day levels of reactivity and yoked for operant reinforcement schedules. Significant differences between the two groups were found on the last day of conditioning and during extinction. Six of the nine experimental subjects showed higher cumulative rate curves than their matched and yoked controls. The concomitant measures (basal resistance, heart rate, etc.) all supported this finding. It was suggested that operant reinforcement of autonomic response tends to maintain a certain level of responding in contrast to persistent adaptation in the control group.
ATTACK, AVOIDANCE, AND ESCAPE REACTIONS TO AVERSIVE SHOCK1
Authors: Azrin N. H. , Hutchinson R. R. , Hake D. F.
Published: March 2006

Aversive stimuli are known to produce the behaviors of both escape and attack. The interaction between these two basic reactions was studied with rats and monkeys using many shock‐escape and shock‐avoidance procedures. All procedures produced attack if a target was present, the attacks occurring shortly after shock delivery. The number of attacks during escape or avoidance was a direct function of the number and duration of shocks received. Consequently, any aspect of the procedure that produced many shocks also produced many attacks such as initial acquisition, extinction, or an increase of the response requirement for escape. The escape tendency acquired prepotency over the tendency to attack since successful escape eliminated attack behavior. The attack tendency retarded escape behavior only during acquisition when the preoccupation with attack precluded the opportunity to learn the escape response. This mutual interference of escape and attack was eliminated when the attack and avoidance tendencies were combined by using biting attack as the shock‐avoidance response. The result was unusually rapid conditioning of the biting‐attack response. These interactions indicate that both the attack and escape tendency should be considered whenever aversive stimulation is delivered.
BEHAVIORAL CONTRAST AND RELATIVE REINFORCEMENT FREQUENCY IN TWO MULTIPLE SCHEDULES1
Authors: Bloomfield T. M.
Published: March 2006

After preliminary variable‐interval training, one group of pigeons was trained on a series of multiple variable‐interval low‐rate reinforcement schedules, while another group was trained on a series of multiple variable‐interval fixed‐ratio reinforcement schedules. Contrast effects were observed as variable‐interval baseline rate changed in a direction away from the change in reinforcement frequency in the other component. The effects of the variable‐interval component on performance in the low‐rate and fixed‐ratio reinforcement components in the multiple schedules were assessed by comparing the birds' performances on each of these schedules alone. Fixed‐ratio reinforcement schedules showed a susceptibility to contrast effects, low‐rate reinforcement schedules did not. The rate of reinforcement in fixed‐ratio schedules at which no interaction occurred in the multiple schedules was higher than that in variable‐interval 1‐min schedules, suggesting that pigeons may prefer time‐based, rather than response‐based, reinforcement.
SOME TEMPORAL PROPERTIES OF BEHAVIORAL CONTRAST1
Authors: Bloomfield T. M.
Published: March 2006

Pigeons were rewarded on a variable time interval for pecking a translucent key illuminated with either a 45° or a vertical line. The key illumination changed every 2 min during daily 1‐hr sessions. When the rates of pecking were stable, reinforcement was omitted in the presence of the 45° line. Responding in the presence of the vertical line increased. This increase did not disappear when responses to the 45° line were once more reinforced, but when reinforcements for responses in the presence of the 45° line were again omitted, responding to the vertical line increased again. After the second alternation of these two procedures, the increased responding to the vertical line appeared when responses were not reinforced in the presence of the 45° line, and disappeared when reinforcement was available during both stimuli. In a second experiment, the key illumination changed between sessions only, so that 1‐hr sessions of reinforcement and non‐reinforcement occurred on alternate days. Responding to the vertical line still increased when responding to the 45° line was not reinforced, but the increase tended to disappear during the session.
RESPONSE PATTERNING DURING STIMULUS GENERALIZATION IN THE RAT1
Authors: Crites Richard J. , Harris Robert T. , Rosenquist Henry , Thomas David R.
Published: March 2006

Nine rats were trained to bar press in the presence of a clicking sound of 6.67 cps (SD) for 1‐min variable‐interval food reinforcement randomly alternated with a clicking sound of 20 cps (SΔ) signifying extinction. After a criterion of 90% of total responses in the presence of the SD was obtained, a generalization test was administered, including values of 6.67, 10.00, 13.33, and 20.00 cps, with responses in the presence of the SD continuing to be reinforced during testing. The test yielded a gradient of response strength with rate highest in the presence of the SD and decreasing with increasing distance from this value. An inter‐response time (IRT) analysis of responding during generalization testing revealed no systematic differences in modal IRT category or in median IRT to the different test stimuli. Mean IRT was lowest in the presence of the SD and increased systematically with increasing distance from this value, supporting the hypothesis that the generalization gradient of response rate is primarily the result of an increasing proportion of “long” IRT responses to stimuli increasingly distant from the SD.