Abstract
Vicarious trial-and-error (VTE) is a behavior observed in rat experiments that seems to suggest self-conflict. This behavior is seen mainly when the rats are uncertain about making a decision. The presence of VTE is regarded as an indicator of a deliberative decision-making process, that is, searching, predicting, and evaluating outcomes. This process is slower than automated decision-making processes, such as reflex or habituation, but it allows for flexible and ongoing control of behavior. In this study, we propose for the first time a robotic model of VTE to see if VTE can emerge just from a body-environment interaction and to show the underlying mechanism responsible for the observation of VTE and the advantages provided by it. We tried several robots with different parameters, and we have found that they showed three different types of VTE: high numbers of VTE at the beginning of learning, decreasing numbers afterward (similar VTE pattern to experiments with rats), low during the whole learning period, and high numbers all the time. Therefore, we were able to reproduce the phenomenon of VTE in a model robot using only a simple dynamical neural network with Hebbian learning, which suggests that VTE is an emergent property of a plastic and embodied neural network. From a comparison of the three types of VTE, we demonstrated that 1) VTE is associated with chaotic activity of neurons in our model and 2) VTE-showing robots were robust to environmental perturbations. We suggest that the instability of neuronal activity found in VTE allows ongoing learning to rebuild its strategy continuously, which creates robust behavior. Based on these results, we suggest that VTE is caused by a similar mechanism in biology and leads to robust decision making in an analogous way.
Highlights
In a study with rats, Tolman [1] observed that they seemingly hesitated when they had to choose between one of two rooms, one of which contained a reward while the other was empty
We investigated the link between vicarious trial-and-error (VTE), neuronal dynamics, and the efficiency of VTE toward learning
It would be important to note that the evolution speed for the Genetic Algorithm (GA), that is, the number of generations to converge on the maximum fitness, differed; the L robots tended to evolve faster than HL / H robots
Summary
In a study with rats, Tolman [1] observed that they seemingly hesitated when they had to choose between one of two rooms, one of which contained a reward while the other was empty. The rats were seen moving their heads from one door to the other as if they were considering which one to choose, which was referred to by Tolman as a conflict-like behavior called vicarious trial-and-error (VTE). In his experiments, Tolman noticed that the number of VTE events (i.e., the number of times that the rat shook its head during one trial) increased at the onset of the learning phase but started to decrease when the performance was stabilized. VTE has been connected to learning efficiency
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