In the horse industry, many have noted that Icelandic horses reacts less fearful in fear eliciting situations in comparison to e.g. Warmblood horses. It is however unknown whether these horses are actually less scared or just reacting less scared.
It may be that Icelandic horses have been selected to react less. A theory could therefore be that Icelandic horses react less fearful, but e.g. a heart rate measure could indicate how fearful they in fact are. This project would demand investigations on both breeds of horses conducted either 1) at the same location (the same stable/farm), or 2) on several farms if not possible to locate a farm with both breeds.