Field observations and survey evidence to assess predictors of mask wearing across different outdoor activities in an Argentine city during the COVID-19 pandemic.

We here studied some potential factors underlying variation in compliance with preventive behaviors against COVID-19 by studying mask wearing during outdoor recreational activities in a midsize city of Argentina in 2020. The originality of present research relies on the complementation of observational (N = 15,507) and survey (N = 578) data and in assessing the determinants of and disposition to the same preventive behavior across activities. In Study 1, we did 8 weeks of unobtrusive systematic observation of mask wearing in outdoor recreational sites as a function of activity (walking, running, and cycling). In Study 2, we ran an online survey (concomitant with the last weeks of the observational study) to measure self-reported mask use and relevant beliefs, including self- and other-regarding motives. Behavioral observations showed that mask wearing declined over time for the three activities as predicted from a social dilemma perspective; nonetheless, compliance significantly differed across activities. Self-reported mask use was predicted by the perceived risk of contagion for the self and for others, perceived comfort costs of wearing masks, and social norms, but not by perceived illness severity or mask effectiveness. We discuss some implications and limitations of present findings for the development of preventive strategies to reduce COVID-19 transmission.

Efecto de marco en un juego de coimas: La relevancia de la dimensión moral / Frame effect in a bribery game: the relevance of the moral dimension

Resumen La corrupción es un fenómeno que involucra componentes morales. Sin embargo, este aspecto no se ha visto reflejado en los experimentos de corrupción de manera inequívoca. De los elementos utilizados para señalizar la presencia de normas, tanto las externalidades negativas como el castigo y la introducción de marcos, han arrojado resultados mixtos o nulos, lo que pareciera cuestionar su validez como instrumentos para estudiar la corrupción. En este experimento se buscó evidencia de que el componente moral está presente en un juego de coimas. Se contó con dos grupos independientes de participantes (N = 106) que fueron expuestos al juego en un marco neutro o con opciones que llevaban etiquetas con contenido semántico concreto (por ejemplo, ofrecer un trato corrupto). Por último, para evaluar la connotación moral de los escenarios de toma de decisiones, se solicitó a los participantes que completaran (post-decisión) una escala de maquiavelismo, que ha estado asociada a diferentes aspectos en la toma de decisiones morales. El experimento logró identificar un claro efecto de marco tanto para los jugadores A como para los B. Los resultados muestran que los participantes eligieron las opciones corruptas en menor medida en el tratamiento con el marco cargado que con el marco neutro. Además, las respuestas al juego mostraron diferencias individuales en el nivel de maquiavelismo, ya que puntajes elevados de maquiavelismo estuvieron directamente asociados a ofertas corruptas, aunque solo en el marco cargado.

Do dogs rescue their owners from a stressful situation? A behavioral and physiological assessment.

Rescue behavior is considered a type of pro-social response, defined as a voluntary action directed to benefit another individual who is in a stressful or dangerous situation. In two experiments, we investigated whether dogs would rescue their owners when the person was trapped inside a wooden box and emitted clear signs of stress. The performance of these dogs was compared against that of a control group in which the owners remained calm while trapped. In addition, to assess if training modulated this behavior, we tested a group of dogs from the military trained in search and rescue tasks (Experiment 1). Results showed that dogs opened the box more frequently when the owner pretended to be stressed than when calm. Training shortened latencies to open the door but not the frequency of the behavior. In Experiment 2, we investigated if emotional contagion could be a possible mechanism underlying dogs' rescue responses by measuring dogs' behavior, heart rate, and saliva cortisol level in the stressed and calm conditions, and also controlled for obedience by having the calm owners call their pets while trapped. We replicated the findings of Experiment 1 as more dogs opened the door in the stressed owner condition than in the calm condition. In addition, we observed an increase in heart rate across trials in the stressed condition and a decrease across trials in the calm condition, but no differences in cortisol levels or stress-related behaviors between conditions. In brief, we found evidence that approximately half of the dogs without previous training showed spontaneous rescue behaviors directed to their owners. Neither was this behavior motivated by obedience nor by the motivation to re-establish social contact with the owner. We conclude that emotional contagion is a plausible mechanism underlying dogs' rescue behavior in the present protocol.

Modulation of the leniency bias in the discursive dilemma.

We experimentally approach the discursive dilemma to gain insight into people's procedural appropriateness judgments. We relied on a vignette in which three people had formed opinions about two skills (premises) of a candidate to decide whether to hire her/him (conclusion). The dilemma arises when different outcomes (hire vs. not hire) are achieved depending on whether the majority opinion is independently considered for each premise or for the global conclusion of each judge. Participants were asked to choose the procedure they thought to be more appropriate to reach a decision. In Experiment 1, we found a leniency effect (a bias to prefer the aggregation procedure that led to hiring the candidate), which was reduced by introducing the participant as a juror with an exogenously provided negative opinion about the candidate's skills. In Experiment 2, we replicated the opinion effect, even when subjects did not participate as jury members. In Experiment 3, we found that the leniency bias was only reduced when participants' negative opinion was aligned with a majority of negative premises, but not with a majority of negative conclusions. We discuss present findings in terms of the identification of empirical regularities that may affect people's procedural legitimacy judgments.

Testing the effect of cooperative/competitive priming on the Prisoner's Dilemma. A replication study.

The replicability crisis in psychology demands direct replications to test the reliability of relevant phenomena. Prime-to-behavior effects have been an area under intense scrutiny given its surprising results. However, intuitive unsurprising effects have been mostly neglected, while they may lack robustness as well. In the present study, we focused on an intuitive prime-to-behavior effect in which Kay and Ross (2003) used a 2x2 design to test cooperation/competition priming crossed with an explicit/non-explicit construal of a Prisoner's Dilemma (PD). They found a stronger assimilation effect of priming when the situational construal anteceded the decision, but we could not reproduce their findings in the present close replication, despite counting on higher power. Even with limitations due to the unavailability of original materials, this replication presents evidence that questions the existence of the original finding, and highlights the need for further replications to get a deeper understanding of the hypothesized effect. The complete project is available at: https://osf.io/dhfns/.

Dogs' recognition of human selfish and generous attitudes requires little but critical experience with people.

There is some dispute regarding the role of experience in the development of dogs´ socio-cognitive abilities in their interaction with people. We sought to provide new evidence to this debate by comparing dogs with contrasting levels of experience with humans, in a task involving the discrimination of human generous and selfish attitudes. To this end, we compared the performance of adult family dogs against that of adult shelter dogs and puppies living in people´s homes. In training trials, the generous experimenter (G) signaled the bowl with food and allowed the dog to eat, whereas the selfish experimenter (S) also signaled the baited bowl, but she/he ate the food before the dog could have access to it. Then, subjects were allowed to freely choose between G and S in the choice test. The main finding was that adult subjects (both family and shelter dogs) developed a preference for G over S, but puppies did not. We conclude that the quality and/or quantity of everyday-contact with people did not affect the discrimination of human attitudes in the present protocol, but the amount of experience with people (in years) did matter. Finally, we discuss the relative role of domestication and ontogeny in the development of dogs´ socio-cognitive abilities.

Direct reciprocity in animals: The roles of bonding and affective processes.

The presence of direct reciprocity in animals is a debated topic, because, despite its evolutionary plausibility, it is believed to be uncommon. Some authors claim that stable reciprocal exchanges require sophisticated cognition which has acted as a constraint on its evolution across species. In contrast, a more recent trend of research has focused on the possibility that direct reciprocity occurs within long-term bonds and relies on simple as well as more complex affective mechanisms such as emotional book-keeping, rudimentary and higher forms of empathy, and inequity aversion, among others. First, we present evidence supporting the occurrence of long-term reciprocity in the context of existing bonds in social birds and mammals. Second, we discuss the evidence for affective responses which, modulated by bonding, may underlie altruistic behaviours in different species. We conclude that the mechanisms that may underlie reciprocal exchanges are diverse, and that some act in interaction with bonding processes. From simple associative learning in social contexts, through emotional contagion and behavioural mimicry, to empathy and a sense of fairness, widespread and diverse social affective mechanisms may explain why direct reciprocity may not be a rare phenomenon among social vertebrates.

Following human pointing: Where do dogs (Canis familiaris) look at to find food?

Domestic dogs (Canis familiaris) are notably skillful in following cues from people (e.g., pointing gestures). However, not much is known about the processing of information available during such tasks. We here focus on one of the earliest of such processes, namely attention. The goal of the present work was to describe variations in dogs' attention towards diverse targets while they solve an object choice task with human pointing. The direction of subjects' gaze was measured in the period comprising one second before and two seconds after the experimenter called the dog and simultaneously performed a static distal pointing gesture towards the correct bowl. We did two consecutive training phases: acquisition and extinction. Dogs spent more time watching the pointer than the pointing gesture itself and the correct than the incorrect bowl. Indeed, the time spent watching the correct bowl was the best predictor of correct choices across phases. We discuss the relevance of these findings for the process of local enhancement.

Dog's discrimination of human selfish and generous attitudes: the role of individual recognition, experience, and experimenters' gender.

Discrimination of and memory for others' generous and selfish behaviors could be adaptive abilities in social animals. Dogs have seemingly expressed such skills in both direct and indirect interactions with humans. However, recent studies suggest that their capacity may rely on cues other than people's individual characteristics, such as the place where the person stands. Thus, the conditions under which dogs recognize individual humans when solving cooperative tasks still remains unclear. With the aim of contributing to this problem, we made dogs interact with two human experimenters, one generous (pointed towards the food, gave ostensive cues, and allowed the dog to eat it) and the other selfish (pointed towards the food, but ate it before the dog could have it). Then subjects could choose between them (studies 1-3). In study 1, dogs took several training trials to learn the discrimination between the generous and the selfish experimenters when both were of the same gender. In study 2, the discrimination was learned faster when the experimenters were of different gender as evidenced both by dogs' latencies to approach the bowl in training trials as well as by their choices in preference tests. Nevertheless, dogs did not get confused by gender when the experimenters were changed in between the training and the choice phase in study 3. We conclude that dogs spontaneously used human gender as a cue to discriminate between more and less cooperative experimenters. They also relied on some other personal feature which let them avoid being confused by gender when demonstrators were changed. We discuss these results in terms of dogs' ability to recognize individuals and the potential advantage of this skill for their lives in human environments.

Estudios Sobre Cooperación en Perros Domésticos: una Revisión Crítica / Studies on Cooperation in Household Dogs: A Critical Review / Estudos sobre Cooperação em Cachorros Domésticos: uma Revisão Crítica

El análisis comparado de la cooperación contribuye al entendimiento tanto de sus orígenes evolutivos como de los mecanismos próximos involucrados en dicho fenómeno. Esta revisión se centra en estudios sobre cooperación en perros domésticos. Para ello se definieron conceptos relacionados con la cooperación, se describieron las razones filogenéticas y ontogenéticas que hacen del perro un buen modelo para el estudio de este fenómeno y se hizo una revisión crítica de los trabajos realizados en este campo. Fueron incluidas investigaciones sobre situaciones cooperativas y sobre las habilidades cognitivas involucradas. Se discuten hipótesis sobre los mecanismos próximos de esta habilidad que incluyen elementos emocionales, motivacionales y de aprendizaje asociativo.

The comparative analysis of cooperation contributes to the understanding of both its evolutionary origins and the proximate mechanisms involved in this phenomenon. This review focuses on studies of cooperation in household dogs, describing the phylogenetic and ontogenetic reasons that make dogs a good model for the study of this phenomenon, and carrying out a critical review of the research carried out in this field, particularly of research regarding cooperative situations and the cognitive abilities involved. The article also discusses hypotheses regarding the proximate mechanisms of this ability, which include emotional, motivational, and associative learning abilities.

A análise comparada da cooperação contribui para o entendimento tanto de suas origens evolutivas quanto dos mecanismos próximos envolvidos nesse fenômeno. Esta revisão se centraliza em estudos sobre cooperação em cachorros domésticos. Para isso, definiram-se conceitos relacionados com a cooperação, descreveram-se as razões filogenéticas e ontogenéticas que fazem do cachorro um bom modelo para o estudo desse fenômeno e fez-se uma revisão crítica dos trabalhos realizados nesse campo. Foram incluídas pesquisas sobre situações cooperativas e sobre as habilidades cognitivas envolvidas. Discutem-se hipóteses sobre os mecanismos próximos dessa habilidade que incluem elementos emocionais, motivacionais e de aprendizagem associativa.

Dogs' Eavesdropping from people's reactions in third party interactions.

Eavesdropping involves the acquisition of information from third-party interactions, and can serve to indirectly attribute reputation to individuals. There is evidence on eavesdropping in dogs, indicating that they can develop a preference for people based on their cooperativeness towards others. In this study, we tested dogs' eavesdropping abilities one step further. In a first experiment, dogs could choose between cooperative demonstrators (the donors) who always gave food to an approaching third person (the beggar); here, the only difference between donors was whether they received positive or negative reactions from the beggar (through verbal and gestural means). Results showed that dogs preferentially approached the donor who had received positive reactions from the beggar. By contrast, two different conditions showed that neither the beggar's body gestures nor the verbal component of the interaction on their own were sufficient to affect the dogs' preferences. We also ran two further experiments to test for the possibility of dogs' choices being driven by local enhancement. When the donors switched places before the choice, dogs chose at random. Similarly, in a nonsocial condition in which donors were replaced by platforms, subjects chose at chance levels. We conclude that dogs' nonrandom choices in the present protocol relied on the simultaneous presence of multiple cues, such as the place where donors stood and several features of the beggar's behavior (gestural and verbal reactions, and eating behavior). Nonetheless, we did not find conclusive evidence that dogs discriminated the donors by their physical features, which is a prerequisite of reputation attribution.

Estudios experimentales sobre corrupción y el problema de la validez externa / Experimental studies on corruption and the external validity problem

El estudio de la corrupción (causas, consecuencias y medios efectivos para combatirla) es difícil debido a la naturaleza usualmente secreta del tipo de relaciones involucradas. Recientemente se han comenzado a realizar estudios experimentales sobre situaciones análogas a las de corrupción para complementar otros abordajes empíricos más tradicionales. El problema principal que se ha planteado sobre estos estudios es el de su validez externa, es decir, si los resultados que se obtienen en el laboratorio son extrapolables a situaciones de corrupción reales. Los objetivos de este artículo son, por un lado, resumir la metodología y los principales resultados de esta nueva área de investigación y, por otro, analizar el problema de su validez externa. Se concluye que si bien algunos resultados son alentadores, parece aconsejable una actitud cautelosa con respecto a la generalización de los mismos. Consecuentemente, se sugiere la necesidad de realizar más estudios empíricos para evaluar la validez externa del área.

Some authors conceive corruption as the misuse or abuse of public power for private benefit. Despite not being full agreement about the conceptual definition of the term, there is consensus that corruption is a widespread welfare-reducing phenomenon affecting institutions all over the world (Rose-Ackerman, 2006). The study of corruption (causes, consequences, and effective means of deterrence) is difficult because of the usually secret nature of the relationships involved. Despite the progress made in cross-country econometric analysis of corruption, on the level of the determinants of behaviour there is still lack of reliable knowledge about the factors that affect people’s corruptibility or the institutional features that affect the incidence of corruption (Abbink, 2006). The new field of experimental studies of corruption has recently emerged in an attempt to complement more traditional studies of corruption. In this paper, we first present a brief review of some of the most significant studies in this nascent area, in especial, we focus on introducing the methodology and main results of bribery experiments. In effect, although corruption is a phenomenon that can come in a variety of forms, the offer and acceptance of bribes has been the main focus of interest of this new experimental area. One of the simples ways in which bribery has been modeled in an experiment has been allowing couples of participants to play a Trust Game that can have negative consequences on the other couples (or on passive third parties, depending on the experiment; Abbink et al., 2002; Barr & Serra, 2009; Cameron et al., 2009). Negative externalities happen when the monetary transfer from the first to the second player (the bribe) is reciprocated by the second player choosing an option that favors the first player but harms others. Researchers have also experimentally implemented the possibility of a monetary punishment when the second player chooses the option with negative externalities (Abbink et al., 2002; Cameron et al., 2009). There are two goals that this new area of research pursues. First, researchers try to find out the micro-determinants of corrupt behavior. Second, researchers try to test the efficacy of different anticorruption policies. One of the main problems with experimental studies of corruption is their external validity, that is, the extent to which experimental results can be extrapolated to understand and combat corruption in real life. The second goal of this article is to discuss the external validity issue in experimental studies of corruption from particular examples from bribery studies. We mention two relevant aspects to assess the external validity of studies: on one hand, generalization among different populations, in which the idea is to evaluate the extent to which the same results persist when populations differ between experiments; on the other hand, situational generalization, in which the idea is to evaluate if results persist when the situation or the context varies. It has been argued (e.g., Levit & List, 2007) that the artificial features of the experimental setup (such as the use of abstract language, the detailed characterization of the corrupt transaction and the scrutiny of participants’ actions by researchers) make the extrapolation inference very problematic. We conclude that, although some results seem promissory (especially, very similar findings between laboratory and field experiments; Armantier & Boly, 2011), it seems recommendable to keep a cautious attitude toward the generalization of laboratory findings because there is not enough data on this field yet. Consequently, we stress that the problem of generalization can be approached empirically, and that it is necessary to have more studies which aim at evaluating the external validity of experiments in an area which pretends to be relevant to applied issues.

Estudios experimentales sobre corrupción y el problema de la validez externa / Experimental studies on corruption and the external validity problem

El estudio de la corrupción (causas, consecuencias y medios efectivos para combatirla) es difícil debido a la naturaleza usualmente secreta del tipo de relaciones involucradas. Recientemente se han comenzado a realizar estudios experimentales sobre situaciones análogas a las de corrupción para complementar otros abordajes empíricos más tradicionales. El problema principal que se ha planteado sobre estos estudios es el de su validez externa, es decir, si los resultados que se obtienen en el laboratorio son extrapolables a situaciones de corrupción reales. Los objetivos de este artículo son, por un lado, resumir la metodología y los principales resultados de esta nueva área de investigación y, por otro, analizar el problema de su validez externa. Se concluye que si bien algunos resultados son alentadores, parece aconsejable una actitud cautelosa con respecto a la generalización de los mismos. Consecuentemente, se sugiere la necesidad de realizar más estudios empíricos para evaluar la validez externa del área.(AU)

Some authors conceive corruption as the misuse or abuse of public power for private benefit. Despite not being full agreement about the conceptual definition of the term, there is consensus that corruption is a widespread welfare-reducing phenomenon affecting institutions all over the world (Rose-Ackerman, 2006). The study of corruption (causes, consequences, and effective means of deterrence) is difficult because of the usually secret nature of the relationships involved. Despite the progress made in cross-country econometric analysis of corruption, on the level of the determinants of behaviour there is still lack of reliable knowledge about the factors that affect people’s corruptibility or the institutional features that affect the incidence of corruption (Abbink, 2006). The new field of experimental studies of corruption has recently emerged in an attempt to complement more traditional studies of corruption. In this paper, we first present a brief review of some of the most significant studies in this nascent area, in especial, we focus on introducing the methodology and main results of bribery experiments. In effect, although corruption is a phenomenon that can come in a variety of forms, the offer and acceptance of bribes has been the main focus of interest of this new experimental area. One of the simples ways in which bribery has been modeled in an experiment has been allowing couples of participants to play a Trust Game that can have negative consequences on the other couples (or on passive third parties, depending on the experiment; Abbink et al., 2002; Barr & Serra, 2009; Cameron et al., 2009). Negative externalities happen when the monetary transfer from the first to the second player (the bribe) is reciprocated by the second player choosing an option that favors the first player but harms others. Researchers have also experimentally implemented the possibility of a monetary punishment when the second player chooses the option with negative externalities (Abbink et al., 2002; Cameron et al., 2009). There are two goals that this new area of research pursues. First, researchers try to find out the micro-determinants of corrupt behavior. Second, researchers try to test the efficacy of different anticorruption policies. One of the main problems with experimental studies of corruption is their external validity, that is, the extent to which experimental results can be extrapolated to understand and combat corruption in real life. The second goal of this article is to discuss the external validity issue in experimental studies of corruption from particular examples from bribery studies. We mention two relevant aspects to assess the external validity of studies: on one hand, generalization among different populations, in which the idea is to evaluate the extent to which the same results persist when populations differ between experiments; on the other hand, situational generalization, in which the idea is to evaluate if results persist when the situation or the context varies. It has been argued (e.g., Levit & List, 2007) that the artificial features of the experimental setup (such as the use of abstract language, the detailed characterization of the corrupt transaction and the scrutiny of participants’ actions by researchers) make the extrapolation inference very problematic. We conclude that, although some results seem promissory (especially, very similar findings between laboratory and field experiments; Armantier & Boly, 2011), it seems recommendable to keep a cautious attitude toward the generalization of laboratory findings because there is not enough data on this field yet. Consequently, we stress that the problem of generalization can be approached empirically, and that it is necessary to have more studies which aim at evaluating the external validity of experiments in an area which pretends to be relevant to applied issues.(AU)

Rational choice, context dependence, and the value of information in European starlings (Sturnus vulgaris).

Both human and nonhuman decision-makers can deviate from optimal choice by making context-dependent choices. Because ignoring context information can be beneficial, this is called a "less-is-more effect." The fact that organisms are so sensitive to the context is thus paradoxical and calls for the inclusion of an ecological perspective. In an experiment with starlings, adding cues that identified the context impaired performance in simultaneous prey choices but improved it in sequential prey encounters, in which subjects could reject opportunities in order to search instead in the background. Because sequential prey encounters are likely to be more frequent in nature, storing and using contextual information appears to be ecologically rational on balance by conditioning acceptance of each opportunity to the relative richness of the background, even if this causes context-dependent suboptimal preferences in (less-frequent) simultaneous choices. In ecologically relevant scenarios, more information seems to be more.

Mechanisms of intake induction of a low-nutritious food in sheep (Ovis aries).

Intake induction refers to the phenomenon by which animals increase consumption of a less-valued meal when followed by a highly-preferred food relative to when followed by no food or by the same less-preferred food. In the Training phase of the present experiment, we assessed the induction effect in sheep using a within-subject design where learning could be tested while controlling for digestive state. Results showed that, once intake reached stability, subjects ate more low-nutritious food (oat hay) when followed than when preceded by a preferred food (soybean meal), supporting the learning hypothesis of induction. The objective of the second, Revaluation, phase of the experiment was to explore the associative mechanism of induction, for which we paired gastrointestinal malaise caused by lithium chloride intoxication with consumption of soybean meal or a control food (wheat bran). Despite subjects partially rejecting soybean meal relative to controls after the aversive conditioning protocol, oat hay consumption seemed unaffected by soybean meal devaluation. We conclude that intake induction in sheep may rely on changes in hedonic properties of the low-nutritious food based on its association with post-ingestive feedback from the preferred food (hedonic hypothesis), but not on an explicit anticipation of the latter (signalling hypothesis).

Visual-olfactory Contact with a Receptive Female Reduces Anxiety in Reward Downshift and Open Field Tests in Male Rats

Ejaculation has been shown to have anxiolytic-like effects in a consummatory Successive Negative Contrast situation. Present research was conducted with the main goal of replicating and testing whether ejaculation is a necessary factor to obtain anti-anxiety effects after socio-sexual stimulation in both a reward downshift situation and in an open field test. In Experiment 1, male rats were tested in the second post-shift session of a 32% to 4% sucrose solution downshift after having the chance of an ejaculation, visual-olfactory contact with a receptive female, or no contact with females. Similarly to treatments with anxiolytic drugs, increments in consumption after the initial consummatory reduction were equivalent for ejaculatory and visual-olfactory conditions relative to controls not exposed to females. In Experiment 2, the same treatments were applied before males were placed in an open field. Ejaculators and visual-olfactory males did not significantly differ from controls in terms of general activity, though both groups had significantly more average time in central areas of the open field than the control group. Altogether, present experiments provided evidence that socio-sexual stimulation in male rats is a sufficient factor in reducing anxiety responses in a reward downshift situation. In addition, this anxiolytic-like effect of ejaculation and socio-sexual stimulation is extensive to novel context situations (AU)

En un artículo previo mostramos que, en ratas, la eyaculación produjo un efecto ansiolítico en una situación de frustración usando un procedimiento de contraste sucesivo negativo consumatorio (CSNc), que implica la reducción abrupta de un reforzador apetitivo. Los experimentos que presentamos tienen como objetivo evaluar si ese efecto se extiende a una situación que implica una estimulación socio-sexual. En el Experimento 1 se evalúa el consumo mediante el tiempo de contacto con el bebedero ante la devaluación del 32% al 4% de una solución azucarada en ratas machos con experiencia sexual previa. Antes del segundo ensayo de la devaluación, las ratas se dividieron en tres condiciones: acceso y eyaculación con una hembra receptiva, contacto visual-olfativo con una hembra receptiva y ningún contacto con hembras. Durante la segunda sesión de la fase de post-cambio, los dos primeros grupos consumieron una proporción mayor de la solución devaluada en relación con el grupo control. En el Experimento 2 se realiza el mismo tratamiento antes de colocar a los animales ante una prueba de campo abierto. Los machos sometidos a eyaculación o contacto visual -olfativo no se diferenciaron de los controles en la ambulación; sin embar- go ambos grupos permanecieron en el área central significativamente más tiempo que los animales pertenecientes al grupo control. Estos resultados extienden el efecto ansiolítico de la eyaculación a la estimulación social-sexual en una condición de disminución de reforzadores apetitivos y en una situación de temor ante lugares novedosos (AU)

Sequential and simultaneous choices: testing the diet selection and sequential choice models.

We investigate simultaneous and sequential choices in starlings, using Charnov's Diet Choice Model (DCM) and Shapiro, Siller and Kacelnik's Sequential Choice Model (SCM) to integrate function and mechanism. During a training phase, starlings encountered one food-related option per trial (A, B or R) in random sequence and with equal probability. A and B delivered food rewards after programmed delays (shorter for A), while R ('rejection') moved directly to the next trial without reward. In this phase we measured latencies to respond. In a later, choice, phase, birds encountered the pairs A-B, A-R and B-R, the first implementing a simultaneous choice and the second and third sequential choices. The DCM predicts when R should be chosen to maximize intake rate, and SCM uses latencies of the training phase to predict choices between any pair of options in the choice phase. The predictions of both models coincided, and both successfully predicted the birds' preferences. The DCM does not deal with partial preferences, while the SCM does, and experimental results were strongly correlated to this model's predictions. We believe that the SCM may expose a very general mechanism of animal choice, and that its wider domain of success reflects the greater ecological significance of sequential over simultaneous choices.

Efecto del sobreaprendizaje en la extinción y reestablecimiento de la respuesta consumatoria / Overtraining and reestablishment in consummatory extinction

Los mamíferos tienen una mayor resistencia a la extinción cuando reciben menos ensayos de adquisición comparados con más ensayos (efecto de sobreaprendizaje en la extinción, ESE). Adicionalmente, si antes de la sesión de extinción se presenta alguna situación semejante a la del aprendizaje, la respuesta extinguida reaparece (restablecimiento, R). En este trabajo se estudió la relación entre el numero de sesiones de adquisición y las respuestas de extinción subsecuentes en una situación consumatoria en ratas. Dos grupos de animales recibieron 108 ó 36 sesiones de adquisición y 12 de extinción. En las sesiones 13 y 14 se evaluó el R. Durante las sesiones de adquisición, los animales tenían acceso a una solución azucarada al 32 por ciento durante 5 minutos, y luego pasaban a una fase de extinción (bebedero vacío) durante 12 sesiones. En el R, durante la sesión 13 cada grupo se dividió en dos. Uno de ellos tuvo acceso al reforzador durante un minuto en otra caja de condicionamiento antes de la sesión de extinción y otro no. Las condiciones de los grupos se invirtieron en la sesión 14. Las variables dependientes fueron bebedero (tiempo que el animal permanecía en el bebedero) y latencia para acercarse al bebedero. Tanto bebedero como latencia exhibieron una extinción más rápida en los animales del grupo 36 que en los del grupo 108 (ESE invertido). Respecto al R, hubo una fuerte reaparición de la latencia pero no de bebedero en los animales expuestos al reforzador. Los resultados se discuten en el contexto de las evidencias que apoyan la presencia de características diferentes entre él condicionamiento de respuestas instrumentales y consumatorias

Anxiolytic-like effect of ejaculation upon frustration.

In three experiments, we studied the consequences of ejaculation upon the frustrative or contrast response of male rats exposed to reward downshift situations (i.e., surprising changes from 32% to 4% sucrose solutions). Similar to what has been found after treatment with anxiolytic agents, consummatory suppression was partially reversed by previous ejaculations in a second postshift trial (Experiments 2 and 3), such a result not having been obtained in a first postshift trial (Experiment 1). Moreover, the effect of ejaculations upon males' behavior during a second postshift trial was transitory, disappearing when assessed during the third and fourth postshift trials (Experiment 3). These results are in accordance with both Amsel's (1958, 1992) frustration theory and Flaherty's (1996) multistage hypothesis of successive negative contrast; the diverse factors that are known to modulate contrast effects are considered, including an interpretation of the present data in terms of the anxiolytic-like effect of the ejaculation.

Psicopatología y cerebro: desde los demonios a los neurotransmisores / Psychopathology and brain: From demons to the neurotransmitters

Las enfermedades mentales fueron y son un problema de relevancia social, cuya conceptualización ha variado en diferentes momentos y contextos históricos. Sin embargo, desde la segunda mitad del siglo XIX, la idea de que los procesos mentales, tanto normales como anormales, son procesos llevados a cabo por el cerebro, comenzó a fortalecerse con hallazgos científicos que argumentaron en su favor. Desde un punto de vista terapéutico, hacia 1970, se dieron grandes progresos en la psiquiatría con el estallido de la psicofarmacologÌa, y, durante el siglo XX, se idearon un conjunto de técnicas terapéuticas derivadas de los principios generales del condicionamiento que evidenciaron gran eficacia en el cambio de la conducta, los pensamientos y las emociones de las personas afectadas por algunos problemas mentales específicos. En este articulo se exploran algunos de los estudios que han aportado evidencias acerca de la neurobiología de ciertos trastornos psicopatológicos, y a su vez, se hace referencia a algunas investigaciones que muestran que, tanto los psicofármacos como la psicoterapia, al obtener reversiones en los síntomas de los pacientes, modifican también aspectos específicos de su funcionamiento cerebral.

Mental disorders have always been a matter of social importance, and the way they have been conceptualized has varied in diverse historical times and contexts. However, since the second half of the 19th century, the idea that mental processes, either normal or abnormal ones, are brain processes, began to grow with scientific facts in its favor. From a therapeutic point of view, in the 1970s, psychiatry experienced a big progress with the development of psychopharmachology, and during the 20th century, psychologists developed some therapeutic technics derived from conditioning principles, which have resulted of great efficiency in changing mental illness patients' behavior, thoughts, and emotions. In this article, we explore some studies that have...