The influence of birth weight and coping style on visual discrimination learning in pigs

Abstract

We investigated visual discrimination ability in domestic piglets by means of a simultaneous visual discrimination task. We started with simple black-and-white geometric stimuli and two reversals. We also investigated the effects of low birth weight and results of the back test (coping style) on learning performance. A lot of piglets are born with a low birth weight due to selection towards big litters. Human low birth weight babies have often learning problems. Animals with an proactive coping style might have problems with learning reversals compared to reactive animals. The outcome of this experiment was that there are no differences in learning ability between normal and low birth weight piglets. All piglets needed a lot of trials to learn the discriminations. Number of vocalizations in the back test correlated moderately and negatively with learning a simple visual discrimination involving one stimulus. Correlations between back test behaviour and reversal learning could not be made, because only five piglets learned the reversal. Further, we investigated if pigs can discriminate between 2D photo's of known and unknown pig heads. In 289 trials not one of the pigs learned to discriminate between two photo's.