Shetland ponies (Equus caballus) show quantity discrimination in a matching-to-sample design.

The research investigates three Shetland ponies’ ability to discern between different quantities of symbols displayed on a computer screen. It finds that the ponies can visually discriminate between different quantities, but find tasks more difficult when the quantities are made up of various stimuli, confirming the hypothesis that the ponies based their decisions on sameness rather than a preference for larger quantities.

Study Methodology and Design

• This research study started with an interest in horses’ numerical competence — a subject with limited data available. Shetland ponies (a type of small horse breed) were chosen as the subjects for this experiment.
• The study focused on testing the ponies’ abilities to discriminate between different quantities displayed on a computer screen. This was done using a matching-to-sample technique. Here, the ponies were presented with two similar quantities. They then had to relate these quantities to another paired in contrasts (1 vs. 2, 3 vs. 4, and 4 vs. 5) of the same stimulus — a dot.
• In a second experiment, the ponies were shown pairs of quantities (all differing by one) of up to five different geometrical symbols. During each test, both more and fewer quantities were presented as samples in a way that allowed each quantity to serve both as a positive and a negative stimulus.

Findings and Results

• The results showed that all three Shetland ponies were able to distinguish between the given quantities of dots, with more than 80% correct responses in two consecutive sessions. However, only one pony managed to distinguish different shapes of geometric symbols at a level of 4 versus 5 items. This suggests that while all the ponies could visually discriminate between different quantities, tasks became more complex when they included mixed stimuli.

Conclusions

• This research confirms the hypothesis that the ponies based their decision on the matching concept of sameness and not on any spontaneous preference for larger quantities.
• These findings contribute to the limited understanding of numerical competence in horses and can serve as a foundation for subsequent studies in this area.