Mormyrid fish as models for investigating sensory-motor integration: A behavioural perspective.

Animals possess senses which gather information from their environment. They can tune into important aspects of this information and decide on the most appropriate response, requiring coordination of their sensory and motor systems. This interaction is bidirectional. Animals can actively shape their perception with self-driven motion, altering sensory flow to maximise the environmental information they are able to extract. Mormyrid fish are excellent candidates for studying sensory-motor interactions, because they possess a unique sensory system (the active electric sense) and exhibit notable behaviours that seem to be associated with electrosensing. This review will take a behavioural approach to unpicking this relationship, using active electrolocation as an example where body movements and sensing capabilities are highly related and can be assessed in tandem. Active electrolocation is the process where individuals will generate and detect low-voltage electric fields to locate and recognise nearby objects. We will focus on research in the mormyrid Gnathonemus petersii (G. petersii), given the extensive study of this species, particularly its object recognition abilities. By studying object detection and recognition, we can assess the potential benefits of self-driven movements to enhance selection of biologically relevant information. Finally, these findings are highly relevant to understanding the involvement of movement in shaping the sensory experience of animals that use other sensory modalities. Understanding the overlap between sensory and motor systems will give insight into how different species have become adapted to their environments.

State-dependent valuation learning in fish: banded tetras prefer stimuli associated with greater past deprivation.

Humans and some birds and insects sometimes prefer alternatives associated with greater past cost or need, sometimes affording losses. It has been proposed that this is widespread because learning may include knowledge about both the physical properties of alternatives and state-dependent fitness gains. We examine the phenomenon for the first time in a fish, the banded tetra (Astyanax fasciatus). During training we paired two different color cues to identical food rewards, one under greater deprivation than the other. We then tested preference between these cues under both deprivation states. Consistent with previous results in other taxa, the fish preferred the cue associated with previous greater deprivation regardless of the condition under which they were tested. These results provide further support to the view that organisms assign value using state-dependent increments in fitness during learning. Although generally adaptive, under experimental conditions state-dependent valuation learning can lead to paradoxical choices.

The social transmission of spatial information in homing pigeons.

We adapted a technique to explore the social transmission of spatial information in homing pigeons Columba livia. Five demonstrator pigeons were first trained to find a food goal within an indoor arena. This arena consisted of nine lidded cups laid out within a 12x12 grid on the floor. The task was to find the goal cup and flip the lid to obtain the food hidden within. Once the demonstrators had reached criterion the experiment proper began. During stage 1 of the experiment, 10 target birds, which had not previously been trained to find the goal, were introduced to the spatial task either in isolation or paired with a demonstrator. We measured how long they took to complete the task, the number of squares crossed on the grid, and the number of incorrect lids flipped. In stage 2, the target birds were introduced to the arena a second time, by themselves, and we compared the performance of the birds in the two treatments. The pigeons that had been introduced to the task with a demonstrator in stage 1 walked further and made more incorrect choices when searching for the food goal in stage 2 than the pigeons that were introduced to the task alone. This indicates that pigeons learn a spatial, food-finding task more effectively when performing the task alone than when accompanied by a knowledgeable conspecific. We discuss possible reasons for this in the light of previous experiments. Copyright 1999 The Association for the Study of Animal Behaviour.