Personality effects on spatial learning: comparisons between visual conditions in a weakly-electric fish

Recent research has explored links between cognition and personality, with prominent hypotheses proposing that personality drives consistent individual differences in cognitive function. These hypotheses particularly expect bolder individuals to be faster, but less accurate, as a trade-off in cognitive function. However, cognitive processes are typically interconnected and defined in more complex terms than simply speed and accuracy. Here we present evidence that personality-based differences in learning rates are a result of differences in decision-making during training in a two-alternative forced-choice spatial memory task. This was examined in the mormyrid fish Gnathonemous petersii in the presence of light, where both vision and the electric sense are available, and in the dark, where visibility is limited and fish rely mostly on electrosensing. The species is adapted for the dark in order to avoid visual predators, thus the presence of light can induce high-risk and the dark low-risk. We show that light condition had little effect on learning, with bolder fish learning faster both in the light and dark condition. Yet the relationship between learning and error rates indicates that the effect on learning is indirectly influenced by accuracy during training. Speed-accuracy trade-offs were not found in decision making, with bolder individuals deciding faster and more accurately both in the light and the dark. Only learning strategy was affected by light, with significantly more fish preferring response to place learning in the dark than in the light, where distal cues were not visible. We conclude that other than effects from the integration of visual information, bolder individuals show a consistently greater tendency to explore and find food-rewards during training. This affects their decision making and in turn their learning performance. We highlight the complexity by which personality-based effects are exhibited in spatial associative learning.