Blocking in eyelid conditioning: Effect of changing the CS-US interval and introducing an intertriai stimulus

Kamin’s three-stage blocking paradigm was investigated in rabbit eyelid conditioning, Two manipulations were examined. A change in the CS-US interval from Stage 1 to Stage 2 did not attenuate blocking. The introduction of a salient stimulus during the intertriai interval in Stage 2 also failed to attenuate blocking. The first result is not consistent with Kamin’s interpretation of the blocking effect in terms of US surprisingness. The second resuit is inconsistent with a prediction based on the Rescorla-Wagner model.     

Effects of schedule and delay of reinforcement on acquisition speed

The effects of schedule of reinforcement (partial vs. consistent) and delay of reward (0 to 20 sec) on running in rats were examined in two investigations. The effects of delay depended upon schedule of reinforcement; acquisition speed decreased as delay increased under consistent reinforcement, a common finding, while acquisition speed was independent of delay under partial reinforcement, a new finding. The partial-reinforcement acquisition effect or PRAE is defined as faster acquisition speed under partial than under consistent reinforcement. Because running speed was independent of delay under partial reinforcement, but decreased as delay increased under consistent reinforcement, the PRAE increased as delay of reinforcement increased.     

Periodic water,interwater interval,and adjunctive behavior in a 24-hour multiresponse environment

To examine the generality of the interreward response effects shown by rats under periodic food delivery, we presented .10 ml of water at minimum interwater intervals that ranged from 8 to 512 sec. Use of a 24-h multiresponse environment allowed evaluation of interdrink responses with respect to their excessiveness, patterning, and functional relationship to the interwater interval. In contrast to the extensive activity-inducing effects of periodic food, the only major excitatory effect of periodic water was increased attention to the water source. Although there were a few bitonic and direct relationships between interwater interval and changes in responding, the great majority of functions were inverse or inconsistent. Further, unlike the increase in drinking under periodic food, total eating decreased under periodic water. The major similarity with food reward was the apparent separation of interreward behavior into three general classes of reward-appropriate foraging responses: area-restricted search after reward, more general search (and waiting), and focal search preceding the next reward delivery.     

Effect on subsequent fixed-interval schedule performance of prior exposure to ratio and interval schedules of reinforcement

In three experiments, we examined the effect on the patterns of responding noted on fixed interval (FI) schedules of prior exposure to a range of interval and ratio schedules. Rats leverpressed for food reinforcement on random ratio (RR), random interval (RI), or variable interval (VI) schedules prior to transfer to FI schedules. In Experiment 1, prior exposure to an RR schedule retarded the development of typical FI patterns of responding. Exposure to a yoked RI schedule produced even greater retardation of typical FI performance. This effect was replicated in Experiment 2, using a within-subjects design. Rats responded on a multiple RR-RI schedule prior to a multiple FI-FI schedule. Typical FI performance emerged more slowly in the component previously associated with the RI than with that associated with the RR. In Experiment 3, exposure to an RR schedule retarded the development of FI performance to a greater extent than did exposure to a VR schedule. The latter schedule was programmed to allow the possibility that inhibitory control would develop after reinforcement. These results confirm that ratio schedules independently result in the disruption of FI responding. This effect was not long lasting and cannot be used plausibly to explain species differences in responding to FI schedules. However, it does suggest that temporal control—as manifested by the transfer of inhibitory control from one schedule to another—could facilitate movement between interval schedules.     

Fluid intelligence and discriminative operant learning of reinforcement contingencies in a fixed ratio 3 schedule

Although intelligence has traditionally been identified as the ability to learn (Peterson, 1925), this relationship has been questioned in simple operant learning tasks (Spielberger, 1962). Nevertheless, recent pieces of research have demonstrated a strong and significant correlation between associative learning measures and intelligence ( [Kaufman et al., 2009] and [Williams et al., 2008] ). The present paper aims to examine the relationship between intelligence and learning, complying with the experimental conditions of discriminative conditioning in a relatively complex free operant task. To that end, a sample of 1600 subjects applying for an ab initio Air Traffic Control training course was tested. The task is expected to allow identifying the specific influence of intelligence on the discrimination between stimulus dimensions. The results show how the relation among learning and intelligence strengthen on those trials which are critical in terms of discrimination.     

Adjunctive behavior of the rat under periodic food delivery in a 24-hour environment

The behavior of 4 rats living in complex environments was monitored 24 h per day during free-feeding baseline and under conditions of periodic access to food. Under the periodic schedules, the minimum interfood interval (IFI) was increased from 16 to 512 sec in an ascending series. Periodic food produced robust overall increases in investigation of the feeder, drinking, general activity, and rearing, but not in wheel-running. The temporal distribution of behavior within the IFI was similar across subjects and supported the hypothesis that some responses were largely time-locked to the period immediately following eating, while other responses expanded to fill the interval. However, these response differences were not adequately captured by present classification schemes. Finally, the distribution of drinking following a food pellet strongly resembled the distribution of drinking following bouts of feeding in baseline. The results suggest that adjunctive behavior stems from three sources: (1) a simple increase in the number of opportunities for expression of normal preprandial and postprandial behavior, (2) an increase in the preprandial behavior directed toward the site of expected food, and (3) an increase in the postprandial distribution of both site-directed and more general exploratory behavior. These findings suggest that adjunctive behavior is not extraneous, but is an orderly distribution of responses ordinarily related to feeding and foraging for food.     

Serial discrimination reversal learning in pigeons as a function of intertrial interval and delay of reinforcement

Pigeons learned a series of reversals of a simultaneous red-green visual discrimination. Delay of reinforcement (0 vs. 2 sec) and intertrial interval (ITI; 4 vs. 40 sec) were varied across blocks of reversals. Learning was faster with 0-sec than with 2-sec delays for both ITI values and faster with 4-sec ITIs than with 40-sec ITIs for both delays. Improvement in learning across successive reversals was evident throughout the experiment, furthermore, even after more than 120 reversals. The potent effects of small differences in reinforcement delay provide evidence for associative accounts and appear to be incompatible with accounts of choice that attempt to encompass the effects of temporal parameters in terms of animals’ timing of temporal intervals.     

Conjunctive schedules of reinforcement IV: Effects on the pattern of responding of changes in requirement at reinforcement

The effects of different schedule requirements at reinforcement on patterns of responding by pigeons were assessed under conjunctive schedules with comparable response-number requirements, Under one conjunctive schedule (conjunctive fixed-interval fixed-ratio schedule), a response was reinforced after a 6-min interval had elapsedand a specific minimum number of responses had been emitted, Under a second conjunctive schedule, a response was reinforced after the 6-min fixed interval and upon completion of a tandem schedule requirement (conjunctive fixed-interval tandem schedule), This schedule retained the same required minimum number of responses as the first conjunctive schedule, but responses were never reinforced according to a fixed-ratio schedule; the tandem schedule was comprised of a fixed-ratio and a small (.1 to 10.0 sec) fixed-interval schedule, Under the conjunctive fixed-interval fixed-ratio schedule, responding was characterized by an initial pause, an abrupt transition to a high response rate, and a second transition to a lower rate that prevailed or slightly increased up to reinforcement, Under the conjunctive fixed-interval tandem schedule, pauses were extended, response rates were lower, and the initial high rate of responding was generally absent, The above effects depended upon the size of the fixed interval of the tandem schedule, The distinct pattern of responding generated by conjunctive fixed-interval fixed-ratio schedules depends upon occasional reinforcement of fixed-ratio responding and not merely on the addition of a minimum number of required responses.     

Frustration effect: The length of blocking interval and magnitude of incentive

In a series of three experiments, forty Sprague-Dawley females were randomly assigned to groups which differed in incentive magnitude in the goalbox. The subjects were then trained for 10 days in a straight alley with no obstruction of approach to the goal. During testing, the rats received two nonblocked and four blocked (delay) trials per day for 11 days. Groups receiving four or nine 45-mg pellets on each trial ran significantly faster following delays than following no delay and tended to be faster following a 4-sec delay than following longer delays. Delay had a similar effect on both running speeds and ingestion rates, with the 4- and 20-sec delays producing a significant frustration effect for running and ingestion in the third experiment.     

Classical conditioning of the rabbit nictitating membrane response: Effects of reinforcement schedule on response maintenance and resistance to extinction

Two experiments were conducted to assess the effects of the introduction of schedules of partial reinforcement (PRF), subsequent to continuous reinforcement training, on the maintenance and resistance to extinction of the rabbit’s nictitating membrane CR. Substantial response levels were maintained by schedules of reinforcement as lean as 15%, and the performance decrements, when observed to be reliable, could not be localized to the immediate effects of one, two, or three consecutive nonreinforced trials by the examination of conditional response probabilities. Moreover, reliable PRF extinction effects were obtained. The relevance of these findings to the purported empirical divergence of PRF effects on classical and instrumental conditioning were discussed.     

Observational learning in the pigeon: Effects of model’s rate of response and percentage of reinforcement

Seventeen pigeons observed a model peck an illuminated key at either a high or a low rate and obtain a high or low percentage of possible reinforcement. Observers were subsequently placed on an automaintenance schedule. Although there was no difference among groups in the number of trials to the first peck, when the present data were compared with other researchers’ automaintenance-acquisition data, there was some indication that modeling reduced the number of trials to the first peck over nonmodeled birds. However, by the end of 20 sessions, the birds that had observed a model pecking at a high rate and with consistent reinforcement pecked significantly faster than those that had observed the model peck at a slow rate or obtain infrequent reinforcement. The conclusion is that two types of information are transferred via a model: first, a correlation between the stimulus and the reinforcer, and second, the specific or minute attributes of the schedule that may produce reinforcement.     

A behavioral field approach to instrumental learning in the rat: I. Partial reinforcement effects and sex differences

The behavioral field approach employs naturalistic observation and simultaneous, multiple recordings of ecologically relevant aspects of behavior-environment interactions. Applying this approach to runway learning in the rat, the inferior acquisition speed of partial reinforcement (PRF) subjects as compared to continuous reinforcement (CRF) subjects was found to result from greater response variability, more sniffing and goal-avoidance behavior, and slower dropping out of collateral behaviors (e.g., drinking and sand-digging). Extinction first produced an increase in exploratory behavior, then displacement activities (e.g., grooming and biting) and goal-avoidance. CRF subjects showed greater response persistence as measured by number of extinction trials to disrupt an established, favored path. PRF subjects showed greater goal persistence as measured by trials to retrace from goalbox. In extinction, while CRF subjects were more inclined to engage in drinking and sand-digging in the startbox, PRF subjects exhibited more biting behavior in the goalbox. The only sex-related differences were superior speeds by female CRF subjects, inferior goal speeds by female PRF subjects during acquisition, and superior goalbox escape learning by females in extinction.     

Effects of signaled reward in instrumental conditioning: Enhanced learning on DRL and DRH schedules of reinforcement

The effects of signaled reward were examined using DRL and DRH schedules of reinforcement. In each case, one group of rats received a brief cue between the reinforced response and the reward, and a second group received brief cues at random times. With the DRL schedule (Experiment 1), signaled reward decreased response rate, increased response efficiency (number of responses per reinforcer), and increased resistence to satiation relative to the control group. With the DRH schedule (Experiment 2), signaled reward increased response rate, efficiency, and resistance to satiation. These results refute an overshadowing explanation of the effects of signaled reward and suggest that food-correlated cues enhance learning of the reinforcement contingencies.     

Potentiation of responding on a VR schedule by a stimulus correlated with reinforcement: Effects of diffuse and localized signals

In Experiment 1, rats were trained to leverpress on a variable ratio (VR) 30 schedule with a 500-msec delay between the reinforced response and food delivery. Subjects that experienced a signal during the delay responded faster than did control subjects that received the stimulus un-correlated with reinforcement. Higher response rates were obtained when the stimulus used to signal reinforcement was auditory rather than visual. Experiments 2 and 3 compared the effects of signaling reinforcement with either a localized or a diffuse light on responding maintained by VR schedules of reinforcement. Elevated response rates were observed with the diffuse stimulus, but the localized stimulus failed to produce such potentiation. Experiment 3 also examined the conditioned reinforcing power of localized and diffuse visual stimuli. These results are discussed with reference to (1) theories of selective association and sign tracking and (2) their implications for current theories of signaling reinforcement.     

Outcome status of students with learning disabilities at ages 21 and 24

This study investigated whether the presence of learning disabilities (LD) at age 10 was related to later schooling, employment, income, receipt of public aid, involvement in crime, and feeling of victimization at ages 21 and 24. Confidential self-report data were collected in a prospective, longitudinal panel study from a sample of 571 students, of whom 60 (10.5%) were children with LD. After controlling for gender, ethnicity, and socioeconomic status, the following results were obtained: The highest postsecondary school attainment for young adults with LD was not significantly different from that of their peers without LD, both at age 21 and age 24. The rate of employment and amount of earned income of young adults with LD were not significantly lower than those of their peers without LD both at age 21 and age 24. Young adults with LD were not significantly different from their peers without LD at age 21 and age 24 with respect to having children, but young adults with LD received significantly more public aid (such as food stamps, supplemental security income, and unemployment compensation) at age 21 but not at age 24. Young adults with LD were not significantly different from their peers without LD in committing crimes or feeling victimized at age 21 and age 24.     

Effects of cross-modal transfer on direct and reversal learning in the rat

In the first experiment, using within- and between-sensory modality CSs, direct and reversal transfer of active avoidance learning was studied in 48 male and 48 female albino rats. Training in each of two sessions employed either a high- or low-intensity light or noise CS. The analyses of both raw score data and proportional or savings score data indicated significant cross-modal transfer in direct as well as reversal learning conditions. Although females learned faster than males, there were no sex differences in amount of transfer. A second experiment, which examined the potential of compound conditioning within the cross-modal learning procedures, replicated the cross-modal results of the first experiment without finding evidence for compound conditioning. These results are interpreted in terms of specific and nonspecific transfer effects during avoidance learning.     

Reversibility of reinforcement between eating and running by schedule changes: A comparison of hypotheses and models

Rats increased eating that produced access to a running-wheel or increased running that produced access to food, depending on which response was potentially deprived, relative to baseline, by the scheduled ratio of responding. Under both schedules, instrumental responding significantly exceeded appropriate baselines of the noncontingent effects of the schedule. The results contradicted the hypothesis that reinforcement is produced by an overall or momentary probability differential between two responses; instead, they supported the condition of response deprivation as a key determinant of reinforcement. Of several recent quantitative models that predict reversibility of reinforcement by schedule changes, only the predictions of the relative response-deprivation model did not differ significantly from the data of either schedule.     

Extinction responding following partial reinforcement: The effects of number of rewarded trials and magnitude of reward

Rats were trained on a daily partial reward schedule of small magnitude of reward (S), nonreward (N), and large magnitude of reward (L), which began with SN or SSNN for all animals. The remainder of the daily schedule was defined by the factorial combination of the number of rewards (1 vs. 3) and the magnitude of reward (S vs. L). Following 18 days of such training, 20 trials of extinction were administered. It was found that increasing the number of rewarded trials in a partial reinforcement schedule decreased resistance to extinction. Furthermore, increased number of large-magnitude rewards reduced resistance to extinction to a greater extent than increased number of small-magnitude rewards.