Maria Helena Leite Hunziker

Learned helplessness: effects of response requirement and interval between treatment and testing

Three experiments investigated learned helplessness in rats manipulating response requirements, shock duration, and intervals between treatment and testing. In Experiment 1, rats previously exposed to uncontrollable or no shocks were tested under one of four different contingencies of negative reinforcement: FR 1 or FR 2 escape contingency for running, and FR1 escape contingency for jumping (differing for the maximum shock duration of 10s or 30s). The results showed that the uncontrollable shocks produced a clear operant learning deficit (learned helplessness effect) only when the animals were tested under the jumping FR 1 escape contingency with 10-s max shock duration. Experiment 2 isolated of the effects of uncontrollability from shock exposure per se and showed that the escape deficit observed using the FR 1 escape jumping response (10-s shock duration) was produced by the uncontrollability of shock. Experiment 3 showed that using the FR 1 jumping escape contingency in the test, the learned helplessness effect was observed one, 14 or 28 days after treatment. These results suggest that running may not be an appropriate test for learned helplessness, and that many diverging results found in the literature might be accounted for by the confounding effects of respondent and operant contingencies present when running is required of rats.

Análise da noção de variabilidade comportamental

ABSTRACT - The purpose of this paper is to analyze the concept of behavioral variability aiming at standardizing thedifferent conceptions and uses of the term. We propose 1) a definition that resorts to the common characteristics underlyingcurrent variability concepts reported in the literature, and 2) the description and systematization of specific aspects of eachone of those uses of the term by means of the following criteria: the content and structure of each concept, its empirical/theoretical and molar/molecular levels of analysis, and types of measurement and codes under which they are specified.The present analysis is an initial attempt at obtaining a behavioral variability taxonomy.Key words: behavioral variability; behavioral selection; learning; methodological analysis; conceptual analysis. No âmbito comportamental, a variabilidade – assimcomo a repetitividade – pode ser funcao de diferentes pro-cessos como, por exemplo, alguns estados fisiologicos al-terados por drogas, lesoes ou patologias diversas (Devenport,1983). Alem disso, nos organismos intactos, a variabilida-de comportamental pode ser funcao de processos decorren-tes da interacao do organismo com seu meio ambiente.Como os demais fenomenos comportamentais, o da varia-bilidade pode ser considerado de duas perspectivas distin-tas: a do seu aparecimento inicial e a da sua manutencao. Oaparecimento e a manutencao sao mencionados de modousual, embora as vezes confuso, como variacao e selecaodo comportamento, respectivamente, entendidos como pro-cessos complementares, necessarios ambos a adaptacao esobrevivencia dos individuos. Portanto, o termo variacaotem um duplo significado, sendo as vezes utilizado paradesignar o fenomeno da variabilidade e em outros momen-tos utilizado para designar o processo de aparecimento deum novo comportamento. Dessa maneira, distinguindo-sefenomeno de processo, e possivel se falar em processos devariacao e selecao tanto da variabilidade como da repetitivi-dade comportamental.Apesar dessa complementaridade entre os processos devariacao e selecao, a perspectiva behaviorista de analise docomportamento tem priorizado o estudo dos processos se-letivos, sendo a sua enfase dada nas relacoes de consequen-ciacao que selecionam determinados padroes comporta-mentais, com pouca analise dos processos de variacao des-Mudanca e a unica constante.(Lucretius, filosofo grego, ha 2000 anos)Em ciencia, a variabilidade (ou variacao de um feno-meno) pode ser analisada como um produto indesejavel dapesquisa, um “ruido” decorrente da falta de controle expe-rimental sobre variaveis desconhecidas ou mesmo de errode mensuracao. Essa variabilidade se entende que siga umpadrao aleatorio descrito por modelos probabilisticos, taiscomo o normal, o bi ou multinomial, entre outros. Entre-tanto, a variabilidade pode ser, em si mesma, um objeto deestudo, considerada como consequencia de um conjunto defatores de interesse tematico. Sendo assim, fenomenos va-riaveis ou aparentemente caoticos vem sendo investigadosem diferentes ciencias (Butz, 1995; Fivas, 1994; Thelen &Smith, 1994), de forma que hoje buscam-se leis que gover-nam a variabilidade da mesma forma como sempre se bus-caram leis responsaveis pelos fenomenos mais repetitivos(Doll & Freeman, 1986).

O desamparo aprendido revisitado: estudos com animais

Learned helplessness is a learning deficit produced by the previous experience with uncontrollable aversive stimuli. The present paper aims at carrying out a critical review of studies on animal learned helplessness. Conceptual and methodological questions related to learned helplessness are considered, along with its theoretical interpretation. We analyze both the historical evolution of studies on learned helplessness and some controversial experimental results obtained during four decades of research. The relationship between learned helplessness and clinical depression is also discussed, with emphasis on the necessity for a rigorous methodological and conceptual analysis.

Aprendizagem de fuga após estímulos apetitivos incontroláveis

Improvements for in-mold polyurethane foam and/or resin products and the ability to provide surface coatings of such products exhibiting bright coloration and reduced colorant migration through utilization of easy-to-use polymeric colorants in simplified and environmentally friendly processing methods are disclosed. The inventive surface coating formulations include polyurethane-reactive polymeric colorants admixed with prepolymer and excess amounts of certain isocyanate compounds. Such a composition is applied (by spraying, for example) to a polyurethane prepolymer (for the production of the internal polyurethane article) which is then introduced within a mold in order to form a particularly shaped or configured polyurethane article with a colored surface coating. Upon curing through exposure to heat, the coating composition reacts with the introduced polyurethane prepolymer to form a surface over the target internal polyurethane. The excess isocyanate present within the surface coating has been found to provide surprisingly good non-migration and non-bleed properties to the polymeric colorant thereby permitting the addition of such a highly desired, high color space, and effective polyurethane colorant within such surface coatings. The specific method as well as colored polyurethane articles are also contemplated within this invention.

Variabilidade comportamental em humanos: efeitos de regras e contingências

Two experiments investigated the learning of variability by undergraduate students. In the experiment 1, four groups (n = 5) were submitted to two schedules of reinforcement for pressing the P or the Q keys at a computer. For the Variability group (VAR) the reinforcement was dependent on high variation among sequences; for the Yoked group (ACO) the reinforcement was given independently of the sequence variability. It was manipulated the order and interval (0 and 3 months) for contingencies presentation. In the second experiment, four groups received these contingencies associated with correct or incorrect instructions (rules). The results showed that: 1) the responding was always more variable under the VAR contingency, 2) under ACO, the behavior was partially influenced by order and interval for contingencies presentation, and by the rules. In both experiments, the subjects were not able to report the contingency that was working. These results point the operant control of the behavior variability observed.

Variabilidade e repetição operantes aprendidas após estímulos aversivos incontroláveis

The aim of the present experiment was to verify whether the previous experience with uncontrollable aversive events interferes in the learning of operant variability and repetition. Rats responses to lever pressure (n=45) were reinforced positively in CRF and FR 4 contingencies and then divided into three groups, exposed to electric shocks that could be either controllable, uncontrollable or none. After that, nine to 12 positive reinforcement sessions were conducted for sequences of four lever pressure responses in a box with two levers (right - D and left - E): half subjects was reinforced for varying (VAR) and half for repeating a same sequence (REP). The results showed that the previous shock treatment did not interfere in the learning of repetition and variability patterns which were only dependent on the contingence in force. These data are in disagreement with the learned helplessness hypothesis prediction.

Um olhar crítico sobre o estudo do desamparo aprendido

Learned helplessness effect has been observed across a wide range of species. This paper introduces the basic characteristics oflearned helplessness experiments performed with infrahwnan subjects. A critical analysis of most of these experiments shows procedural and measurement problems in addition to a low defftional precision. Some results produced by a modified procedure are reported, which were able to generate more accurate data (compared to conventional procedures) with respect to the operant learning under study. It is proposed that well established learned helplessness experiments can make significant contributions to behavior analysis, particularly to the investigation of aversive control and to the effects of non-contingency.

Longitudinal investigation on learned helplessness tested under negative and positive reinforcement involving stimulus control.

In this study, we investigated whether (a) animals demonstrating the learned helplessness effect during an escape contingency also show learning deficits under positive reinforcement contingencies involving stimulus control and (b) the exposure to positive reinforcement contingencies eliminates the learned helplessness effect under an escape contingency. Rats were initially exposed to controllable (C), uncontrollable (U) or no (N) shocks. After 24h, they were exposed to 60 escapable shocks delivered in a shuttlebox. In the following phase, we selected from each group the four subjects that presented the most typical group pattern: no escape learning (learned helplessness effect) in Group U and escape learning in Groups C and N. All subjects were then exposed to two phases, the (1) positive reinforcement for lever pressing under a multiple FR/Extinction schedule and (2) a re-test under negative reinforcement (escape). A fourth group (n=4) was exposed only to the positive reinforcement sessions. All subjects showed discrimination learning under multiple schedule. In the escape re-test, the learned helplessness effect was maintained for three of the animals in Group U. These results suggest that the learned helplessness effect did not extend to discriminative behavior that is positively reinforced and that the learned helplessness effect did not revert for most subjects after exposure to positive reinforcement. We discuss some theoretical implications as related to learned helplessness as an effect restricted to aversive contingencies and to the absence of reversion after positive reinforcement. This article is part of a Special Issue entitled: insert SI title.

Behavioral variability as avoidance behavior: Behavioral variability as avoidance behavior

This study aimed to investigate whether variable patterns of responses can be acquired and maintained by negative reinforcement under an avoidance contingency. Six male Wistar rats were exposed to sessions in which behavioral variability was reinforced according to a Lag contingency: Sequences of three responses on two levers had to differ from one, two or three previous sequences for shocks to be avoided (Lag 1, Lag 2 and Lag 3, respectively). Performance under the Lag conditions was compared with performance on a Yoke condition in which the animals received the same reinforcement frequency and distribution as in the Lag condition but behavioral variability was not required. The results showed that most of the subjects varied their sequences under the Lag contingencies, avoiding shocks with relatively high probability (≥ 0.7). Under the Yoke procedure, responding continued to occur with high probability, but the behavioral variability decreased. These results suggest that behavioral variability can be negatively reinforced.