Interocular transfer of learning in horses (Equus caballus)

Laterality of horses associated with emotionality in novel situations

“…Just as Bogen originally suggested in 1985, it seems that the right hemisphere (which receives most of its direct visual input largely from the left eye in the horse and other species with laterally positioned eyes; see Introduction) seems to be specialised for the processing of stimuli that elicit negative emotional responses or, rather, fear and arousal in response to a novel stimulus, whereas the left hemisphere (and right eye) is specialised for processing positive emotion. We are aware that horses are capable of interocular transfer of information: they recognise a visual stimulus presented to one eye when it is presented to the opposite eye (Hanggi, 1999). Despite this, the expression of a significant preference for use of the left eye in states of heightened emotionality shows that direct visual input to the activated right hemisphere is the option selected by the animal.…”

Cognition and learning in horses (Equus caballus): What we know and why we should ask more

“…Many horse trainers will claim that each side of the horse is a "new side" and that horses are likely to react in novel ways when the sides are switched. Because of this, a common training belief is to ask the horse to approach a human with both eyes, as opposed to one more than the other (Hanggi, 1999). There is no anatomical reason for why horses would be incapable of brain lateralization (Olivares et al, 2001;Aboitiz et al, 2003).…”

“…Indeed, in what appears to be contradictory evidence to these anecdotal claims, horses were taught a basic discrimination task using a positive visual stimulus and a negative visual stimulus while one eye (right or left) was covered. Horses were able to learn the task with one eye covered and replicate it while the "learning eye" was covered and the untrained eye was uncovered (Hanggi, 1999). Horses could then perform a reversal of the initial task.…”

“…Horses could then perform a reversal of the initial task. This would be indicative of interocular transfer, or the ability to transfer information across brain hemispheres (Hanggi, 1999).…”

Differential Outcome Effect in the Horse

“…Correspondence regarding this article should be sent to Sadahiko Nakajima, Department of Psychology, Kwansei Gakuin University, Nishinomiya, Hyogo 662-8501, Japan (E-mail: nakajima@kwansei.ac.jp). nation (Hanggi, 1999b), learning set (Hanggi, 1997), categorization (Hanggi, 1999a), and psychophysical investigations of visual acuity, depth perception, and steropsis (Timney & Keil, 1992, 1996. Although these studies provided considerable information about the sensory systems and the discriminative behavior of this species, our knowledge is still limited and has not yet been widely used by equine trainers.…”