To produce or not to produce? Contrasting the effect of substance abuse in social decision-making situations.

Substance use disorders (SUD) have been related to high criminal justice costs, expensive healthcare, social impairment, and decision-making deficits. In non-social decision-making tasks, people with SUD tend to take more risks and choose small immediate rewards than controls. However, few studies have explored how people with SUD behave in social decision-making situations where the resources and profits depend directly on participants' real-time interaction, i.e., social foraging situations. To fulfill this gap, we developed a real-time interaction task to (a) compare the proportion of producers (individuals who tend to search for food sources) and scroungers (individuals who tend to steal or join previously discovered food sources) among participants with SUD and controls with respect to the optimal behavior predicted by the Rate Maximization Model, and (b) explore the relationship between social foraging strategies, prosocial behavior, and impulsivity. Here participants with SUD (n = 20) and a non-user control group (n = 20) were exposed to the Guaymas Foraging task (GFT), the Social Discounting task (SD), and the Delay Discounting task (DD). We found that participants in the control group tended to produce more and obtain higher profits in contrast to substance abuser groups. Additionally, SD and DD rates were higher for scroungers than producers regardless of the group. Our results suggest that producers tend to be more altruistic and less impulsive than scroungers. Knowing more about social strategies and producers' characteristics could help develop substance abuse prevention programs.

Probabilistic reinforcement precludes transitive inference: A preliminary study.

In the basic verbal task from Piaget, when a relation of the form if A > B and B > C is given, a logical inference A > C is expected. This process is called transitive inference (TI). The adapted version for animals involves the presentation of a simultaneous discrimination between stimuli pairs. In this way, when A+B-, B+C-, C+D-, D+E- is trained, a B>D preference is expected, assuming that if A>B>C>D>E, then B>D. This effect has been widely reported using several procedures and different species. In the current experiment TI was evaluated employing probabilistic reinforcement. Thus, for the positive stimuli a .7 probability was administered and for the negative stimuli a .3 probability was administered. Under this arrangement the relation A>B>C>D>E is still allowed, but TI becomes more difficult. Five pigeons (Columba Livia) were exposed to the mentioned arrangement. Only one pigeon reached the criterion in C+D- discrimination, whereas the remaining did not. Only the one who successfully solved C+D- was capable of learning TI, whereas the others were not. Additionally, it was found that correct response ratios did not predict BD performance. Consequently, probabilistic reinforcement disrupted TI, but some positional ordering was retained in the test. The results suggest that TI might be affected by associative strength but also by the positional ordering of the stimuli. The discussion addresses the two main accounts of TI: the associative account and the ordinal representation account.

Individual differences could explain the failure in transitive inference formation in pigeons using probabilistic reinforcement.

In propositional logic, it is stated that "for if A is predicated for every B, and B for every C, A must necessarily be predicated of every C". Following a similar logical process, it can be said that If A > B and B > C, then A > C, this is called transitive inference (TI). Piaget developed a verbal task to evaluate TI in children. Subsequent studies adapted this task for animals using a conditioned discrimination between five-terms sequence of stimuli A + B-, B + C-, C + D-, and D + E-. If subjects prefer B over D during test, it is assumed that TI has occurred. In this experiment, we analyzed the effects of task complexity on TI by using a five-terms sequence of stimuli associated with probabilistic outcomes during training, in pigeons. Thus, both stimuli are reinforced in each pair but with different probability, 0.8 for + stimulus and 0.2 for the-stimulus. We found that performance during C + D- pair is impaired and preference in the test pair BD is affected. However, this impairment is dependent on individual differences in performance in C + D- pair. We compare our findings with previous research and conclude that Pavlovian mechanisms, as well as ordering of stimuli, can account for our findings.

The distractor intensity is related to the rightward shift of the response rate distribution in a peak procedure in pigeons.

The expected effect of interrupting the light that signals the to-be-estimated fixed Interval in a peak procedure is a shift rightward of the peak time. Nevertheless, it has not been studied the effect of inserting a distractor using a peak procedure in pigeons. In this experiment, two lights of different intensities were used as distractors (i.e., 10 and 50 luxes). They elapsed for 5 s, during a to-be-estimated interval of 30 s. It was observed an immediate decrease of the response rate as the distractor was inserted and a rightward shift of the response rate distribution, both related to the distractor intensity. Our results support other findings using different species and with different stimuli modalities,suggesting that rats, mice, and pigeons could share a common timing mechanism.

Response rate correlates with indifference points in a delay-discounting procedure.

To study how effort affects reward value, we replicated Fortes, Vasconcelos and Machado's (2015) study using an adjusting-delay task. Nine pigeons chose between a standard alternative that gave access to 4 s of food, after a 10 s delay, and an adjusting-delay alternative that gave access to 12 s of food after a delay that changed dynamically with the pigeons' choices, decreasing when they preferred the standard alternative, and increasing when they preferred the adjusting alternative. The delay value at which preference stabilized defined the indifference point, a measure of reward value. To manipulate effort across phases, we varied the response rate required during the delay of the standard alternative. Results showed that a) the indifference point increased in the higher-response-rate phases, suggesting that reward value decreased with effort, and b) in the higher-response-rate phases, response rate in the standard alternative was linearly related to the indifference point. We advance several conceptions of how effort may change perceived delay or amount and thereby affect reward value.

Corrigendum: Transitive Inference Remains Despite Overtraining on Premise Pair C+D.

[This corrects the article DOI: 10.3389/fpsyg.2018.01791.].

Transitive Inference Remains Despite Overtraining on Premise Pair C+D.

Transitive inference (TI) has been studied in humans and several animals such as rats, pigeons and fishes. Using different methods for training premises it has been shown that a non-trained relation between stimuli can be stablished, so that if A > B > C > D > E, then B > D. Despite the widely reported cases of TI, the specific mechanisms underlying this phenomenon remain under discussion. In the present experiment pigeons were trained in a TI procedure with four premises. After being exposed to all premises, the pigeons showed a consistent preference for B over D during the test. After overtraining C+D- alone, B was still preferred over D. However, the expected pattern of training performance (referred to as serial position effect) was distorted, whereas TI remained unaltered. The results are discussed regarding value transfer and reinforcement contingencies as possible mechanisms. We conclude that reinforcement contingencies can affect training performance without altering TI.

Pigeons and the Ambiguous-Cue Problem: A Riddle that Remains Unsolved.

The ambiguous-cue task is composed of two-choice simultaneous discriminations involving three stimuli: positive (P), ambiguous (A), and negative (N). Two different trial types are presented: PA and NA. The ambiguous cue (A) served as an S- in PA trials, but as an S+ in NA trials. When using this procedure, it is typical to observe a less accurate performance in PA trials than in NA trials. This is called the ambiguous-cue effect. Recently, it was reported in starlings that the ambiguous-cue effect decreases when the stimuli are presented on an angled (120°) panel. The hypothesis is that the angled panel facilitates that the two cues from each discrimination are perceived as a compound, precluding value transfer via a second-order conditioning mechanism. In this experiment, we used pigeons and a flat panel. Nevertheless, our data were quite similar to the previous data in starlings. We conclude that the form of the panel cannot explain the ambiguous-cue effect. Several alternatives to be explored in future experiments are suggested. The riddle of the ambiguous-cue problem still remains unsolved.

Autoshaped choice in artificial neural networks: implications for behavioral economics and neuroeconomics.

An existing neural network model of conditioning was used to simulate autoshaped choice. In this phenomenon, pigeons first receive an autoshaping procedure with two keylight stimuli X and Y separately paired with food in a forward-delay manner, intermittently for X and continuously for Y. Then pigeons receive unreinforced choice test trials of X and Y concurrently present. Most pigeons choose Y. This preference for a more valuable response alternative is a form of economic behavior that makes the phenomenon relevant to behavioral economics. The phenomenon also suggests a role for Pavlovian contingencies in economic behavior. The model used, in contrast to others, predicts autoshaping and automaintenance, so it is uniquely positioned to predict autoshaped choice. The model also contemplates neural substrates of economic behavior in neuroeconomics, such as dopaminergic and hippocampal systems. A feedforward neural network architecture was designed to simulate a neuroanatomical differentiation between two environment-behavior relations X-R1 and Y-R2, [corrected] where R1 and R2 denote two different emitted responses (not unconditionally elicited by the reward). Networks with this architecture received a training protocol that simulated an autoshaped-choice procedure. Most networks simulated the phenomenon. Implications for behavioral economics and neuroeconomics, limitations, and the issue of model appraisal are discussed.

Efectos de la dispersión de alimento sobre la elección y los patrones de exploración / Effects of Food Dispersion on Choice and Exploration Patterns

Una variable poco estudiada en el área de forrajeo y elección de parches es la distribución del alimento. Dos parches con similar densidad de alimento pero distinta distribución implican diferentes tiempos de búsqueda y, en consecuencia, diferente exposición a posibles predadores. Se estudió el efecto de la dispersión de alimento sobre la elección, exploración y explotación de parche. Se expuso a un grupo de ratas a un instrumento con una zona de elección y dos parches topográficamente iguales y con la misma cantidad de alimento, pero diferente dispersión: alimento concentrado en un solo lugar vs alimento disperso en ocho puntos. Los animales permanecieron durante más tiempo en el parche con alimento concentrado, mientras que en el parche disperso realizaron visitas breves y exhaustivas respecto al vaciado. Los animales desarrollaron patrones de exploración típicos para cada una de las zonas. Se sugiere que los animales establecieron la zona de elección y el parche concentrado como zonas seguras de exploración.

The distribution of food has not been widely studied in the areas of foraging and patch choice. Search time and the potential exposure to predators vary when animals are exposed to two patches that have similar food density but different food distribution. The effects of food dispersion on choice, exploration, and exploitation of two patches was studied. A group of rats was placed in an experimental apparatus that had a choice area and two patches that were topographically identical and contained the same amount of food but varied in food dispersion: either the food was concentrated in a single place or the food was dispersed in eight different locations. Results showed that the rats remained a longer time in the concentrated patch and showed shorter, exhaustive visits to the patch where the food was dispersed. Rats developed different exploration patterns for each of the areas. The preferred areas for exploration were both the choice area and the concentrated patch.

Racionalidad en la elección y el efecto del costo irrecuperable / Rationality in choice and the sunk cost effect

En este manuscrito el autor hace una reflexión sobre el estudio de la elección en animales y humanos, así como las teorías que se han construido alrededor de este concepto. Primero, hace referencia a las teorías que han centrado su atención en las consecuencias de cada elección y la forma en que esto las determina. Posteriormente, plantea cómo estas propuestas han llevado a suponer un sujeto que elije racionalmente, según los principios básicos de la elección racional que proponen los economistas. Finalmente, el autor muestra la manera en que el principio de racionalidad se puede cuestionar a partir del efecto del costo irrecuperable.

Discriminación de fuentes de control temporal en programas de reforzamiento de intervalo / Discrimination of behavioral control sources in interval schedules of reinforcement

Whitaker, Lowe y Wearden reportaron un patrón diferencial de distribución de respuestas en un programa mixto de intervalo fijo de dos componentes, en función de la razón existente entre las duraciones de ambos intervalos. Estos resultados se explicaron aludiendo a la existencia de fuentes diferenciadas de control conductual para ambos componentes. En el presente estudio se pretendía contrastar esta hipótesis incluyendo una señal contextual que señalaba el programa de intervalo activo. Se utilizaron ocho ratas distribuidas en dos grupos con diferente razón y se compararon dos fases, una con discriminativo y otra sin este. Se encontró que la inclusión de la señal alteró la tasa de respuestas en los componentes de menor duración.

Whitaker, Lowe and Wearden reported a differential response pattern using a mixed two-component fixed-interval schedule of reinforcement, considering the ratio between the duration of both intervals. These results were explained in regards to the differential behavioral control sources for each component.This study was intended to contrast that hypothesis by including a contextual cue to mark the beginning of each active interval schedule. Eight rats were assigned to two groups with different ratio. In each ratio two conditions were in effect: one with a cue and the other without it. The results showed that the inclusion of the cue changed the response rate in the components with less duration.