Interaction of procedural factors in human performance on yoked schedules

The effect of brief mindfulness training on the micro-structure of human free-operant responding: Mindfulness affects stimulus-driven responding

BACKGROUND AND OBJECTIVES

The current study examines the extent to which mindfulness impacts on operant conditioning processes, and explores the suggestion that mindfulness training serves to make humans more sensitive to the current reinforcement contingencies with which they are presented. In particular, the effect of mindfulness on the micro-structure of human schedule performance was explored. It was expected that mindfulness might impact bout-initiation responding to a greater degree than within-bout responding, premised on the assumption that bout-initiation responses are habitual and not under conscious control, but within-bout responses are goal-directed and conscious.

METHODS

Nonclinical participants experienced one of three brief (15min) interventions: focused attention breathing exercise (mindfulness), an unfocused attention breathing exercises, or no intervention. They then responded on a multiple random ratio (RR) random interval (RI) schedule.

RESULTS

In the no intervention and unfocused attention groups, overall and within-bout response rates were higher on the RR than the RI schedule, but bout-initiation rates were the same on the two schedules. However, for the mindfulness groups all forms of responding were higher for the RR than the RI schedule. Previous work has noted that habitual, and/or unconscious or fringe-conscious events, are impacted by mindfulness training.

LIMITATIONS

A nonclinical sample may limit generality.

CONCLUSIONS

The current pattern of results suggests that this is also true in schedule-controlled performance, and offers an insight into the manner in which mindfulness alongside conditioning-based interventions, to bring all responses under conscious control.

Human free-operant performance varies with a concurrent task: Probability learning without a task, and schedule-consistent with a task

Three experiments examined human rates and patterns of responding during exposure to various schedules of reinforcement with or without a concurrent task. In the presence of the concurrent task, performances were similar to those typically noted for nonhumans. Overall response rates were higher on medium-sized ratio schedules than on smaller or larger ratio schedules (Experiment 1), on interval schedules with shorter than longer values (Experiment 2), and on ratio compared with interval schedules with the same rate of reinforcement (Experiment 3). Moreover, bout-initiation responses were more susceptible to influence by rates of reinforcement than were within-bout responses across all experiments. In contrast, in the absence of a concurrent task, human schedule performance did not always display characteristics of nonhuman performance, but tended to be related to the relationship between rates of responding and reinforcement (feedback function), irrespective of the schedule of reinforcement employed. This was also true of within-bout responding, but not bout-initiations, which were not affected by the presence of a concurrent task. These data suggest the existence of two strategies for human responding on free-operant schedules, relatively mechanistic ones that apply to bout-initiation, and relatively explicit ones, that tend to apply to within-bout responding, and dominate human performance when other demands are not made on resources.

Factors controlling the micro-structure of human free-operant behaviour: Bout-initiation and within-bout responses are effected by different aspects of the schedule

Two experiments examined factors controlling human free-operant performance in relation to predictions based on the nature of bout-initiation and within-bout responding. Overall, responding was higher for a random ratio (RR) than a random interval (RI) schedule, with equal rates of reinforcement. Bout-initiation rates were not different across the two schedules, but within-bout rates were higher on the RR schedule. Response cost reduced overall rates of responding, but tended to suppress bout-initiation responding more than within-bout responding (Experiments 1 & 2). In contrast, reinforcement magnitude increased all forms of responding (Experiment 2). One explanation consistent with these effects is that bout-initiation responses are controlled by overall rates of reinforcement through their impact on the context (i.e. are stimulus-driven), but that within-bout responses are controlled by response reinforcement (i.e. are goal-directed). These current findings are discussed in the light of these theoretical suggestions.

Behavioral resurgence in individuals varying in depression, anxiety, and autism-associated tendencies

Resurgence is the reappearance of a previously reinforced, but then extinguished behavior, when an alternative behavior that has been reinforced to replace it is also extinguished. This phenomenon has been suggested as important in the re-occurrence of many clinical problems, but little is known currently about the relationship between this process and different psychopathological traits. This experiment addressed this gap by comparing the levels of resurgent behavior in participants scoring lower or higher on depression-, anxiety-, and autism-related characteristics. Sixty participants completed an experimental task of three phases. In the first, they were presented with a concurrent RR-5 ext schedule, in the second with a conc ext RR-5 schedule (each lasting 6min), and finally with a conc ext ext schedule (lasting 2 min). Following this, all participants completed the Beck Depression Inventory, State-Trait Anxiety Inventory, and Autism Quotient, questionnaires provided. Participants showed a resurgence of responding at test from the response extinguished in Phase 2 that was greater for those with lower levels of depression, but high levels of anxiety. These findings are discussed in terms of their implications for understanding individual differences in terms of psychiatric symptomatology, for their treatment, and in terms of theoretical predictions derived for the various psychopathologies.

Exaggerated acquisition and resistance to extinction of avoidance behavior in treated heroin-dependent men

OBJECTIVE

Addiction is often conceptualized as a behavioral strategy for avoiding negative experiences. In rodents, opioid intake has been associated with abnormal acquisition and extinction of avoidance behavior. Here, we tested the hypothesis that these findings would generalize to human opioid-dependent subjects.

METHOD

Adults meeting DSM-IV criteria for heroin dependence and treated with opioid medication (n = 27) and healthy controls (n = 26) were recruited between March 2013 and October 2013 and given a computer-based task to assess avoidance behavior. For this task, subjects controlled a spaceship and could either gain points by shooting an enemy spaceship or hide in safe areas to avoid on-screen aversive events. Hiding duration during different periods of the task was used to measure avoidance behavior.

RESULTS

While groups did not differ on escape responding (hiding) during the aversive event, heroin-dependent men (but not women) made more avoidance responses during a warning signal that predicted the aversive event (analysis of variance, sex × group interaction, P = .007). Heroin-dependent men were also slower to extinguish the avoidance response when the aversive event no longer followed the warning signal (P = .011). This behavioral pattern resulted in reduced opportunity to obtain reward without reducing risk of punishment. Results suggest that, in male patients, differences in avoidance behavior cannot be easily explained by impaired task performance or by exaggerated motor activity.

CONCLUSIONS

This study provides evidence for abnormal acquisition and extinction of avoidance behavior in opioid-dependent patients. Interestingly, data suggest that abnormal avoidance is demonstrated only by male patients. Findings shed light on cognitive and behavioral manifestations of opioid addiction and may facilitate development of therapeutic approaches to help affected individuals.

Testing the role of reward and punishment sensitivity in avoidance behavior: a computational modeling approach

Exaggerated avoidance behavior is a predominant symptom in all anxiety disorders and its degree often parallels the development and persistence of these conditions. Both human and non-human animal studies suggest that individual differences as well as various contextual cues may impact avoidance behavior. Specifically, we have recently shown that female sex and inhibited temperament, two anxiety vulnerability factors, are associated with greater duration and rate of the avoidance behavior, as demonstrated on a computer-based task closely related to common rodent avoidance paradigms. We have also demonstrated that avoidance is attenuated by the administration of explicit visual signals during "non-threat" periods (i.e., safety signals). Here, we use a reinforcement-learning network model to investigate the underlying mechanisms of these empirical findings, with a special focus on distinct reward and punishment sensitivities. Model simulations suggest that sex and inhibited temperament are associated with specific aspects of these sensitivities. Specifically, differences in relative sensitivity to reward and punishment might underlie the longer avoidance duration demonstrated by females, whereas higher sensitivity to punishment might underlie the higher avoidance rate demonstrated by inhibited individuals. Simulations also suggest that safety signals attenuate avoidance behavior by strengthening the competing approach response. Lastly, several predictions generated by the model suggest that extinction-based cognitive-behavioral therapies might benefit from the use of safety signals, especially if given to individuals with high reward sensitivity and during longer safe periods. Overall, this study is the first to suggest cognitive mechanisms underlying the greater avoidance behavior observed in healthy individuals with different anxiety vulnerabilities.

Effects of Mands on Instructional Control: A Laboratory Simulation

The effects of two types of mands on participants' adherence to instructions were examined across two groups using procedures based on Hackenberg and Joker (Journal of the Experimental Analysis of Behavior 62:367-383, 1994). Participants were presented with instructions describing a pattern of responding for producing points later exchanged for money and were exposed to choice trials in which a progressive-time (PT) and a fixed-time (FT) schedule were concurrently available. The instructions initially described how to optimize point production; however, the PT schedule was manipulated over the course of the experiment such that response patterns maximizing point production differed across conditions. All participants experienced the same experimental arrangement, and the two groups differed only in the form of the mand contained in the instructions presented to them. The instructions for the directive group contained the mand "you must…" (i.e., command) preceding the instructed response pattern, whereas the non-directive group instructions contained the mand "you might consider…" (i.e., suggestion) preceding the instructed response pattern. Results indicated that instruction type influenced response patterns across changing contingencies. The directive group exhibited greater adherence to the instruction than the non-directive group when instruction following was less profitable. Results are interpreted in terms of Skinner's analysis of verbal behavior, and implications for practical application are discussed.

Behaviourally inhibited temperament and female sex, two vulnerability factors for anxiety disorders, facilitate conditioned avoidance (also) in humans

Acquisition and maintenance of avoidance behaviour is a key feature of all human anxiety disorders. Animal models have been useful in understanding how anxiety vulnerability could translate into avoidance learning. For example, behaviourally inhibited temperament and female sex, two vulnerability factors for clinical anxiety, are associated with faster acquisition of avoidance responses in rodents. However, to date, the translation of such empirical data to human populations has been limited since many features of animal avoidance paradigms are not typically captured in human research. Here, using a computer-based task that captures many features of rodent escape-avoidance learning paradigms, we investigated whether avoidance learning would be faster in humans with inhibited temperament and/or female sex and, if so, whether this facilitation would take the same form. Results showed that, as in rats, both vulnerability factors were associated with facilitated acquisition of avoidance behaviour in humans. Specifically, inhibited temperament was associated with higher rate of avoidance responding, while female sex was associated with longer avoidance duration. These findings strengthen the direct link between animal avoidance work and human anxiety vulnerability, further motivating the study of animal models while also providing a simple testbed for a direct human testing.

Role of stimulus-stimulus pairing in matching-to-sample procedure: cross-species comparison of humans and pigeons

The present experiment examined whether, in a matching-to-sample (MTS) procedure, a relation between two stimuli, a sample and a comparison, could be established as a result of just stimulus-stimulus pairing, even if back up reinforcers were never provided for the conditional relation between the sample and comparison stimuli, but rather only for the comparison stimulus. A procedure called "pseudo matching-to-sample" was used in which, when S1 was presented as a sample stimulus, two comparison stimuli (C1 and C2) were presented, and only responses to C1 were reinforced. Conversely, when S2 was presented, only responses to C3 (and not C4) were reinforced. In other words, organisms experiencing this procedure could discriminate C1 from C2, and C3 from C4, by simple discrimination without regard to the conditional sample stimuli. In order to examine cross-species differences, responding by humans in this procedure was compared to that by pigeons. Although the humans developed a discriminative function for the sample stimuli, that is, the humans' responding was affected by both the sample stimuli and the reinforcers, responding by the pigeons was affected solely by the reinforcers. These data suggest that, in this procedure, humans (but not pigeons) are able to learn relations among stimuli simply as a result of stimulus-stimulus pairing.

Tipo de reforçador como variável moduladora dos efeitos da história em humanos

Para investigar como o tipo de reforçador afeta o comportamento em FI após diferentes histórias de reforço, universitários foram expostos a FR ou DRL, que liberavam pontos por pressionar um botão. Alguns participantes trocavam pontos por fotocópias (Condição 1), por dinheiro (Condição 2) ou apenas recebiam os pontos (Condição 3). Subseqüentemente, todos foram expostos a FI. O FR produziu taxas de respostas altas e constantes independentemente do tipo de reforçador utilizado. O FI produziu taxas altas para os participantes das Condições 1 e 2 e baixas para os participantes da Condição 3. O DRL produziu baixas taxas que aumentaram durante o FI subseqüente. Os resultados sugerem que tanto contingências históricas quanto presentes controlaram o comportamento dos participantes e que o tipo de reforçador pode favorecer o responder em taxa alta e constante sob FI após exposição a uma contingência de FR.

Acquisition, extinction and temporal discrimination in human conditioned avoidance

Two experiments were conducted with the aim of designing a videogame for the study of human conditioned avoidance. Participants had to destroy enemy spaceships with the goal of increasing the score in a counter. Coloured signals might announce the launching of a bomb that could hit participant's spaceship producing a 30 points decrease in participant's score. Three groups of participants were trained in discriminating between a warning signal (W) and a safety signal (S) in Experiment 1. Instrumental group could avoid the loss of points by hiding the spaceship before the offset of W. Participants in the Yoked group received the same treatment received by their instrumental partners, regardless of their behaviour. In the Pavlovian group, W was always followed by the loss of points, regardless of participant's behaviour. Discrimination between W and S was better in the Instrumental groups than in the Yoked and Pavlovian control groups. Experiment 2 found extinction of avoidance when the warning signal was not followed by the bomb. Temporal discrimination was found within the participants that received the instrumental contingency in both experiments, with higher avoidance response towards the end of the warning signal. Temporal discrimination disappeared after extinction in Experiment 2.

Efeitos de contingências de punição sobre os desempenhos verbal e não verbal

O presente estudo investigou a influência de contingências de punição sobre os desempenhos verbal (resposta de relato) e não verbal (resposta de escolha). Estudantes universitários foram expostos a uma tarefa de escolha de acordo com o modelo. Após a resposta de escolha, a pergunta "Você acertou?" era apresentada e o participante deveria emitir a resposta de relato, indicando uma dentre duas alternativas, "SIM" e "NÃO". No Experimento 1, o feedback "Incorreto. Você perdeu 1 ponto" foi programado para a resposta de relato e, no Experimento 2, o feedback foi contingente à resposta de escolha. No Experimento 1, o feedback exerceu funções punitivas sobre a resposta de relato e, na maioria das condições, não afetou a resposta de escolha. No Experimento 2, o feedback não exerceu controle sobre a resposta de escolha, embora tenha influenciado as respostas de relato. Esses resultados sugerem que os desempenhos verbal e não verbal são funcionalmente independentes. O presente estudo evidencia o caráter operante do relato e, ao identificar possíveis variáveis de controle desse comportamento, contribui para uma maior fidedignidade dos dados obtidos por meio de auto-relatos.

Instruções e iniqüidade de reforços: efeitos sobre o comportamento competitivo

O presente estudo investigou se a precisão da instrução afetaria os efeitos da iniqüidade de reforços. Trinta estudantes universitários, separados em duplas, escolheram entre trabalhar sozinho ou competir com o parceiro. Na alternativa individual, os pontos foram distribuídos igualmente entre os participantes; na alternativa de competição, a distribuição de pontos foi manipulada no decorrer das condições de modo que o Participante 1 ganhava mais pontos que o Participante 2, ou vice-versa. Algumas duplas receberam informação completa sobre a distribuição de pontos (instrução precisa); outras receberam informação indicando que, algumas vezes, um participante receberia mais pontos que o outro (instrução imprecisa); e, as demais, não receberam nenhuma informação (sem instrução). A instrução imprecisa produziu escolha acentuada por competição para ambos participantes, a instrução precisa gerou escolhas sensíveis às manipulações na iniqüidade e, na ausência de instruções, ambos resultados foram observados. Foi concluído que a instrução precisa gerou estratégias mais eficientes de fuga e esquiva da iniqüidade.