Correlation between dichromatic colour vision and jumping performance in horses

- Both green and blue colours are suitable for testing the correlation between dichromatic colour vision and performance.
- The owner of the horses gave written consent and the work received institutional approval.
- The riders came in a straight line to the fences and at a constant pace in order to give the horses the correct and natural balance positioning to jump.
- A member of the research team recorded the mistakes the horses made, on which colour and after how many jumps.
- Touching of the fences was clearly heard by the observer and was confirmed by evaluating the video soundtrack afterwards.
- The median difference was equal to 2.5 bars and only 2/20 horses made more errors on the green than on the blue bars.
- In the indoor arena, significantly more touches and faults occurred on the blue fences compared to the green fences.
- The median difference between the colours for the mares (n = 4) was equal to 5.5 for the sum of both scores and 3.5 for the fallen bars.
- For the stallions and geldings (n = 16) the median difference between colours was equal to 2 for the sum of both scores and 1 for the fallen bars.
- In the outdoor arena there was no significant difference between errors made on blue and green for the faults only (median difference 0.5 bars, P = 0.5) or both touches and faults (median difference −0.5 bars, P = 1.0).

There is general agreement that horses have dichromatic colour vision with similar capabilities to human beings with red-green colour deficiencies. However, whether colour perception has an impact on equine jumping performance and how pronounced the colour stimulus might be for a horse is unknown. The present study investigated the relationship between the colour of the fences (blue or green) and the show jumping performance of 20 horses ridden by two riders using an indoor and outdoor set of green and blue fences.In the indoor arena, significantly more touches and faults were made on blue fences in comparison to green fences (median difference of 2.5 bars). When only touched bars were included, a significant median difference of one bar was found. Mares (n = 4) demonstrated more faults and had a significantly greater difference in touches and faults between the two colours than male horses (n = 16). Repeating the same experiment with eight horses in an outdoor grass arena revealed no significant differences between the two colours. In order to draw any definite conclusions, more research concerning the colour perception, influence of contrast with the arena surface and sex of horse is required.