Influence of multiple action–outcome associations on the transition dynamics toward an optimal choice in rats

When faced with familiar versus novel options, animals may exploit the acquired action–outcome associations or attempt to form new associations. Little is known about which factors determine the strategy of choice behavior in partially comprehended environments. Here we examine the influence of multiple action–outcome associations on choice behavior in the context of rewarding outcomes (food) and aversive outcomes (electric foot-shock). We used a nose-poke paradigm with rats, incorporating a dilemma between a familiar option and a novel, higher-value option. In Experiment 1, two groups of rats were trained with different outcome schedules: either a single action–outcome association (“Reward-Only”) or dual action–outcome associations (“Reward-Shock”; with the added opportunity to avoid an electric foot-shock). In Experiment 2, we employed the same paradigm with two groups of rats performing the task under dual action–outcome associations, with different levels of threat (a low- or high-amplitude electric foot-shock). The choice behavior was clearly influenced by the action–outcome associations, with more efficient transition dynamics to the optimal choice with dual rather than single action–outcome associations. The level of threat did not affect the transition dynamics. Taken together, the data suggested that the strategy of choice behavior was modulated by the information complexity of the environment.     

Synergistic Effects of Selenium Nanoparticles and Vitamin E on Growth,Immune-Related Gene Expression,and Regulation of Antioxidant Status of Nile Tilapia (Oreochromis niloticus)

Biological Trace Element Research - The present study was conducted to investigate the effects of nano-selenium (Nano Se) or/and vitamin E (VE) on growth performance, blood health, intestinal...     

A gaze bias with coarse spatial indexing during a gambling task

Researchers have used eye-tracking methods to infer cognitive processes during decision making in choice tasks involving visual materials. Gaze likelihood analysis has shown a cascading effect, suggestive of a causal role for the gaze in preference formation during evaluative decision making. According to the gaze bias hypothesis, the gaze serves to build commitment gradually towards a choice. Here, we applied gaze likelihood analysis in a two-choice version of the well-known Iowa Gambling Task. This task requires active learning of the value of different choice options. As such, it does not involve visual preference formation, but choice optimization through learning. In Experiment 1 we asked subjects to choose between two decks with different payoff structures, and to give their responses using mouse clicks. Two groups of subjects were exposed to stable versus varying outcome contingencies. The analysis revealed a pronounced gaze bias towards the chosen stimuli in both groups of subjects, plateauing at more than 400 ms before the choice. The early plateauing suggested that the gaze effect partially reflected eye-hand coordination. In Experiment 2 we asked subjects to give responses using a key press. The results again showed a clear gaze bias towards the chosen deck, this time without any influence from eye-hand coordination. In both experiments, there was a clear gaze bias towards the choice even though the gaze fixations did not narrowly focus on the spatial positions of choice options. Taken together, the data suggested a role for gaze in coarse spatial indexing during non-perceptual decision making.