Discrimination training in infant,preweanling, and weanling rats: Effects of prior learning experiences with the discriminanda

Rats were given continuous reinforcement (CRF), partial reinforcement (PRF), or successive discrimination (D) training in an alley from 11–14 (Age 1) or 15–18 (Age 2) days of age. Reinforcement was the opportunity to suckle the dry nipples of an anesthetized dam. Following a 10-day interval, all animals were given 4 successive days of discrimination training with food pellets as reinforcement. Control groups were given only the second phase of training. In the first phase, D subjects of both ages responded appropriately to the discriminative stimuli, and the PRF subjects of both ages ran significantly slower than CRF subjects. In the second phase, only the CRF subjects of Age 1 showed behavioral discrimination. All three Age 2 groups discriminated, but the discrimination developed earliest after Phase I CRF and latest after Phase I PRF. Both Age 1 control groups showed a late-developing discrimination, but neither Age 2 control group discriminated. The results suggest that infant and preweanling rats can learn both positive and negative expectancies of appetitive events, respond appropriately, and retain and transfer these expectancies to new learning. The reinforcement value of dry suckling and the effects of stimulus preexposure in infant rats are also discussed.     

Blocking and enhancement of fear conditioning by appetitive CSs

Prior research on Pavlovian-to-instrumental transfer has shown that when a CS previously associated with shock (AvCS+) is presented contingent upon a choice response to a discriminative stimulus for food reinforcement, it facilitates discrimination learning. Conversely, a response-contingent CS previously associated with the absence of shock (AvCS?) retards discrimination learning. To evaluate whether these findings reflect across-reinforcement blocking and enhancement effects, two experiments investigated the effects of appetitively conditioned stimuli on fear conditioning to a novel stimulus that was serially compounded with the appetitive CS during conditioned-emotional-response (CER) training. Although there were no differential effects of the appetitive CSs in CER acquisition, Experiment 1, using a relatively weak shock US, showed that a CS previously associated with food (ApCS+) retarded CER extinction to the novel stimulus, in evidence of enhanced fear conditioning to that stimulus. In addition, Experiment 2, using a stronger shock US, showed that a CS previously associated with the absence of food (ApCS?) facilitated CER extinction to the novel stimulus, in evidence of weaker fear conditioning to that stimulus. These results parallel traditional blocking effects and indicate not only that an ApCS+ and an ApCS? are functionally similar to AvCSs of opposite sign, but that their functional similarity is mediated by common central emotional states.     

Dissociation of conditioned appetitive and consummatory sexual behavior: Satiation and extinction tests

Sexual responses were conditioned in male Japanese quail using the opportunity to copulate with a female as the unconditioned stimulus (US). The conditioned stimulus (CS) was a 3-D object made of a taxidermically prepared female quail head mounted on a terry-cloth body. Both appetitive conditioned responses (approach and proximity to the CS) and consummatory conditioned responses (mount and cloacal contact directed toward the CS) developed when 2-min presentations of the CS were followed immediately by the US, but not when the CS and US were separated by trace intervals of 10 or 20 min (Experiment 1). Postconditioning sexual satiation suppressed conditioned cloacal contact responses more than conditioned approach to the CS (Experiment 2), and “acute” extinction suppressed both conditioned mounting and conditioned cloacal contact responses more than conditioned approach to the CS (Experiment 3). These results demonstrate a functional dissociation between conditioned appetitive and consummatory responses and imply that the motivational and/or associative mechanisms underlying the two types of behavior are distinct.     

Intertrial interval effects in pavlovian serial feature positive discriminations

The effects of the intertrial interval (ITI) on learning and performance in Pavlovian appetitive serial feature positive (SFP) discriminations were examined in three experiments with rats. With longer ITIs, acquisition was more rapid, and there was less transfer of the feature’s behavioral control to a separately trained target cue, suggesting that longer ITIs encouraged the use of an occasion setting strategy. Behavior was also affected by discrimination-specific ITIs. Rats were trained with two SFP discriminations. The overall ITI was held constant, but the intervals between trials of one discrimination were varied by intermixing different numbers of trials from the other discrimination. Learning was more rapid when the intervals between trials of a single discrimination were longer. A sequential analyses showed that performance on a trial was impaired when it was preceded by a trial that included the same target cue but with the opposite trial outcome. The results are discussed in the frameworks of proactive interference effects and deletion-comparator processes (Cooper, Aronson, Balsam, & Gibbon, 1990.)     

Disruption of overlearned discriminative behavior in monkeys (Cebus paella) by delay of reward

Previous work has shown that when a delay of reward (DOR) is introduced into a well-learned discrimination, even gradually, discriminative performance deteriorates and, with moderately long DORs, does not recover with practice. The present experiment assessed whether the decrement in performance was due to an associative loss or to a decline in the incentive value of the reward object caused by the DOR. Cebus monkeys were trained on a simple visual discrimination and tested with either a DOR or an identical delay period which preceded the appearance of S+ and S? (“predelay” trials); reinforcement on predelay trials was immediate. On half of the daily trials, the animals were given the option of choosing either the DOR or the predelay trial. The duration of the delay was increased gradually until terminal delays of 32 to 128 sec were reached. All four animals maintained almost errorless performance on predelay trials; in contrast, their error rate reached 36% on DOR trials. Surprisingly, none of the animals learned to choose predelay over DOR trials. Both results were interpreted in terms of the incentive loss hypothesis.     

The benefits of aggressive traits: A study with current and former street children in Burundi

Aggressive behavior in children and youths is commonly associated with exposure to violence and maltreatment. Consequently, aggressive behavior has often been explained as a form of reactive behavior in response to violence-inflicted mental suffering. However, perpetrating violence can become appealing, fascinating and exciting, i.e., may acquire appetitive, self-rewarding aspects. We postulated that this appetitive form of aggression reduces the vulnerability for developing Posttraumatic Stress Disorder (PTSD) in insecure and violent environments. Furthermore we investigated the extent to which reactive aggression and appetitive aggression account for recent violent behavior in children and youths. We conducted semi-structured interviews in a sample of 112 children and youths (M_age = 15.9 years) recruited from the streets, families and a residential center for vulnerable children in Burundi. We investigated the cumulative exposure to traumatic events and to domestic and community violence, assessed the recently committed offenses, the severity of PTSD symptoms, and the potential for reactive and appetitive aggression. Reactive aggression was positively related to PTSD, whilst appetitive aggression was negatively related to PTSD. Children higher in appetitive aggression were also more likely to display violent behavior. These results suggest that an appetitive perception of violence may be an useful adaption to insecure and violent living conditions reducing the vulnerability of children for trauma-related mental disorders. However, positive feelings experienced through violent or cruel behavior are also an important risk factor for ongoing aggressive behavior and therefore need to be considered in prevention strategies.     

The Impact of Daily Discrimination on Sleep/Wake Problem Trajectories Among Diverse Adolescents

This study examines how everyday discrimination is associated with 6-day trajectories of sleep/wake problems, operationalized as sleep disturbance and daytime dysfunction, among 350 diverse adolescents (M_age = 14.27, SD = 0.61, 69% female; 22% African American, 41% Asian American, 37% Latinx; 24% multiethnic/racial; across participating schools, 72% of students eligible for free/reduced price lunch) in the Northeastern United States. Adolescents encountering discrimination experienced changes in sleep/wake problem trajectories (i.e., significant increases in same-day sleep/wake problems), whereas adolescents reporting no discrimination experienced no changes in trajectories (Cohen’s ds = .51–.55). Multiethnic/racial (compared to monoethnic/racial) adolescents experiencing everyday discrimination reported greater same-day sleep/wake problems, yet steeper decreases in sleep/wake problems suggesting stronger impact coupled with faster return to baseline levels.     

Two Roads Diverged: Young Children's Ability to Judge Distance

In the present studies, we investigated 4- and 5- to 6-year-olds' ability to compare the distances covered by a direct route to a location and an indirect route to the same location. The distances ranged between 16 and 22 feet. The routes were visible from a single vantage point, and objects serving as landmarks were sometimes located along the routes. We found clear demonstrations of the two classic Piagetian distance errors—the direct-indirect error , in which children judge that a direct route and an indirect route cover the same distance, and the interposed object error , in which children judge that a route is shorter when it is segmented by an object located somewhere along the route. The interposed object error occurred because children focused on only one segment of the route, which was consistent with Piaget's explanation of the error. However, in contrast to Piaget, we found that about 40% of 4-year-olds could successfully avoid the direct-indirect error, and in addition, when the routes were visually displayed, they could also avoid the interposed object error. It is important that they also gave correct explanations for why the indirect route was longer, by referring to the fact that it was not straight. For these children at least, the interposed object error was due to difficulty they had representing routes, rather than to a misconception of distance. We suggest that future research should examine whether that may also be true for younger children.     

Informational properties of infinite numbers of objects in concurrent discriminations by monkeys

Eight rhesus monkeys were trained on a counterbalanced series of concurrent, two-choice, discrimination tasks that provided different numbers of correct or incorrect objects as lists of discriminanda. Small, large, or infinite lengths of correct or incorrect object lists were combined in different tasks, and acquisition performances were compared. When tasks had an infinite number of objects in their correct list and a small number (4) in their incorrect list, acquisition entailed significantly less error than was seen when a small number of correct objects was paired with an infinite incorrect list. This pattern of outcomes seemed attributable to novelty preference. However, comparison of error distributions from tasks with infinite. list lengths to distributions from analogous tasks with fixed list lengths provided some basis for interpreting the way monkeys integrated information that emerged from the temporally discriminative properties of the tasks. One prospective concern was whether or not these performances represented behaviors like those seen in human cognitive discriminations of frequency of occurrence.     

Immunization to learned helplessness in appetitive noncontingent contexts

We examined immunization against learned helplessness in 36 dogs. The experiment consisted of five phases: (1) appetitive contingent training, (2) immunization training, (3) inescapable noise training, (4) recovery, and (5) an appetitive noncontingent test. There were six groups: (1) a group immunized by controllable and predictable noise, (2) a group immunized by controllable but unpredictable noise, (3) a group immunized by uncontrollable but predictable noise, (4) a group given uncontrollable and unpredictable noise during immunization training, (5) a group not submitted to any treatment during the immunization phase, followed by uncontrollable noise, and (6) a group not submitted to any treatment. The immunization effect was assessed by measuring the acquisition of an appetitive response when food was not contingent upon responding. Our results demonstrate that the immunization effect can be observed in a noncontingent appetitive context. The effects of escapable noises that ensure immunization against the motivational deficit and predictable noises that immunize against the associative deficit seem to be additive.     

Use of Restricted Item Response Models for Examining Item Difficulty Ordering and Slope Uniformity

This article demonstrates the utility of restricted item response models for examining item difficulty ordering and slope uniformity for an item set that reflects varying cognitive processes. Twelve sets of paired algebra word problems were developed to systematically reflect various types of cognitive processes required for successful performance. This resulted in a total of 24 items. They reflected distance-rate–time (DRT), interest, and area problems. Hypotheses concerning difficulty ordering and slope uniformity for the items were tested by constraining item difficulty and discrimination parameters in hierarchical item response models. The first set of model comparisons tested the equality of the discrimination and difficulty parameters for each set of paired items. The second set of model comparisons examined slope uniformity within the complex DRT problems. The third set of model comparisons examined whether the familiarity of the story context affected item difficulty for two types of complex DRT problems. The last set of model comparisons tested the hypothesized difficulty ordering of the items.     

Learned helplessness in an appetitive discrete-trial T-maze discrimination test

Four groups of rats were exposed to response-contingent, yoked noncontingent, or en masse food deliveries in a Skinner box or to no experimental pretreatment. All groups were subsequently tested for transfer of the learned-helplessness effect to an appetitive discrete-trial T-maze discrimination employing experimenter-blind procedures. The yoked group showed retarded discrimination learning in comparison with the response-contingent and naive control groups but not in comparison with the en masse control group. This nonsignificant difference between the yoked group and the en masse group may reflect the effect of limited exposure to uncontrollability in the en masse group. The groups did not differ in terms of the speed of maze traversal. The latter result suggests that the learned-helplessness effect observed in discrimination was not due to a competing response.     

Preference effects on acquisition and retention of concurrent discriminations by rhesus monkeys

Ten rhesus monkeys were trained on five tasks, each of which consisted of eight concurrently presented object discrimination problems. Sequences of presentation were devised to allow one, two, or three new tasks to intervene between acquisition and retention tests or to provide a 30-day period of no testing. Equivalent and proficient performances were obtained in all retention tests, and no relationship was observed between retention and the initial preference characteristics of various objects. Object pReferences did produce significant influences upon acquisition, but these effects were not as pronounced in early tasks as in later ones. An additional retention test provided support for the contention that monkeys do not necessarily process information about specific object pair discriminations. Rather, they appeared to retain a list of previously rewarded objects even when object pairings were different from those provided during acquisition. Concurrent discriminations involving many distinct objects were resistant to interference and independent of preference characteristics over long retention periods.     

Pavlovian appetitive discriminative conditioning inAplysia californica

Three experiments demonstrated Pavlovian appetitive discrimination learning in the marine mollusc,Aplysia californica. In each experiment, subjects were exposed to two conditioned stimuli; one stimulus (CS+) was paired with food presentations and the other stimulus (CS?) was never followed by food. In Experiments 1 and 3 different chemosensory stimuli were used, and in Experiment 2 different tactile stimuli were used. For both types of conditioned stimuli, bite responses occurred significantly more often to the CS+ than to the CS?. Experiment 2 also showed thatAplysia could learn a reversal of this discrimination. Experiment 3 showed that nonreinforced presentations of CS+ resulted in a decline in the frequency of conditioned biting. The implications of these results for neurobiological analyses of learning are discussed.     

First-year engineering students' difficulties in visualization and drawing tasks

Visualizing parts, meaning interpreting the views of an object which has been represented in a drawing, is a fundamental skill in engineering. However, learning deficiencies and difficulties have been observed among engineering undergraduates, and there is a high failure rate in drawing courses. In order to determine the origin of these deficiencies, a qualitative design has been developed based on personal interviews. A group of students was interviewed to analyse the solution process they applied to three visualization problems with increasing difficulty. The steps they took were structured and categorized along with the difficulties and deficiencies which were detected. Most of the students affirmed that they did not possess methodology to solve these problems and relied on trial and error and intuition. The results seem to indicate that there are specific difficulties and that it is possible to define a set of skills which guide students through the process of visualizing parts.     

Spanking and subsequent behavioral problems in toddlers: A propensity score-matched,prospective study in Japan

Harsh or frequent spanking in early childhood is an established risk factor for later childhood behavioral problems as well as mental disorder in adulthood in Western societies. However, few studies have been conducted in Asian populations, where corporal punishment is relatively accepted. Moreover, the impacts of occasional spanking on subsequent behavioral problems remain uncertain. This study sought to investigate prospectively the association between the frequency of spanking of toddlers and later behavioral problems in Japanese children using national birth cohort data. We used data from the Longitudinal Survey of Newborns in the 21st Century, a population-based birth cohort data set collected by the Japanese Ministry of Health, Labour, and Welfare (N = 29,182). Frequency of spanking (“never”, “sometimes” and “always”) and child behavioral problems were assessed via a caregiver questionnaire when the child was 3.5 years old and again at 5.5 years. Propensity score matching was used to examine the association between frequency of spanking and child behavioral problems, adjusting for parental socioeconomic status, child temperament and parenting behaviors. Compared to children who were never spanked, occasional spanking (“sometimes”) showed a higher number of behavioral problems (on a 6-point scale) (coefficient: 0.11, 95% CI: 0.07–0.15), and frequent spanking (“always”) showed an even larger number of behavioral problems compared with “sometimes” (coefficient: 0.08, 95% CI:0.01–0.16). Spanking of any self-reported frequency was associated with an increased risk for later behavioral problems in children.     

Multiple deficits in the retention of an appetitively motivated behavior across a 24-h period in rats

Recent investigations have found a multiphasic retention function associated with avoidance training (e.g., Holloway & Wansley, 1973a, b). The present experiment was done to determine if a similar retention function also describes appetitively motivated behavior. Rats were allowed access to preferred solution in the shock compartment of a passive avoidance apparatus. Then either .25 h after the appetitive preexposure or at successive 3-h intervals up to 24 h, the rats were administered one-trial passive avoidance training consisting of a strong shock presented in the shock compartment. The retention of the appetitive preexposure was determined by its effect on performance of the passive avoidance task as measured 24 h after the shock trial. The results demonstrated that the retention function associated with the appetitive preexposure was phasic with an alternation between high and low retention every 12 h. Specifically, retention was higher after the .25-, 9-, 12-, and 24-h intervals than after 3-, 6-, 15-, and 18-h intervals. These results are consistent with prior research on the retention of avoidance training.     

Pavlovian aversive to instrumental appetitive transfer: Evidence for across-reinforcement blocking effects

Rats received Pavlovian aversive (shock) conditioning in which white noise was established for different groups as a CS+, CSO, or CS?. Then, in an appetitive T-maze discrimination, the CSs were presented contingent upon a designated correct response for which food reinforcement was factorially varied at 0, 1, 2, or 4 pellets. Although the CS+ suppressed and the CS? facilitated speed of running in the correct arm at the start of discrimination training, these effects extinguished rapidly and did not interact with reward magnitude. Furthermore, choice learning was faciltated by the CS+ and retarded by the CS?, with these effects being comparable for the 1- to 4-pellet reinforcement conditions, but absent for the 0-pellet condition. These findings are difficult to reconcile with a transfer interpretation positing a general signaling property of the CS and are better interpreted as across-reinforcement blocking effects: By predicting a preferred outcome (safety) comparable to the preferred outcome of food reinforcement, the CS? blocks (retards) the association of reinforcement and the S^D; conversely, by predicting a nonpreferred (shock) outcome discrepant from the preferred food outcome, the CS+ “counterblocks” (enhances) the association of reinforcement and the S^D.     

Signaling and affective functions in Pavlovian conditioning

The present study employed a Pavlovian-instrumental-transfer paradigm to investigate the role of conditioned fear in appetitive discrimination learning. Each of three Pavlovian training procedures was used to establish a conditioned fear excitor (CS+), a “neutral” CS (CSo), and a conditioned fear inhibitor (CS?). Then, the CSs were administered to rats in the three groups contingent upon the rewarded response in a difficult visual discrimination. In addition, half of each group received shock punishment for each incorrect response. Relative to CSo, CS+ facilitated performance in contrast to the usual interfering effect of conditioned suppressors; conversely, CS? retarded performance even when its reinforcing action (fear inhibition) was potentiated by punishment for the incorrect response. These results, together with other findings showing a reversed outcome when the CSs are administered for the incorrect response, indicate that Pavlovian conditioning comprises both general signaling and affective functions, the former reflecting a basic “expectancy” or nominal type of cognitive processing in the rat.     

Visual discrimination of letter-like forms and its relationship to achievement over time in children with learning disabilities

The purpose of this study was to better understand whether visual discrimination abilities are related to reading intelligence and other achievement areas in children with learning disabilities and normally achieving children. Children with visual discrimination problems were identified using the Gibson letter-like visual discrimination task. This task was given to a large sample of children with learning disabilities as well as a sample of normally achieving children. All children were followed throughout elementary school. Results indicated that children with learning disabilities who had visual discrimination problems at 6 or 7 years of age performed more poorly in reading and general achievement over the elementary school years in comparison to the other children with learning disabilities and compared to normally achieving children. Discussion centers around the importance of this skill for reading.