Horse Welfare, Laterality, Hair Whorls & Cognitive Bias

Is the glass half-empty or half-full? Research has found that seeing the glass is half full makes people happier, healthier, and wealthier. The optimist sees the glass as half full, while the pessimist sees the glass as half empty. Cognitive bias is the term used by researchers studying the brain processes that determine whether a person has an optimistic or a pessimistic view of the world. Did you know that horses and other animals have cognitive biases?

A cognitive bias is an error in thinking that occurs when people or animals are processing and interpreting information in their world affected by conflicting information or emotional states. One of the first studies of this phenomenon using laboratory rats as test subjects showed that rats in unpredictable environments had a more pessimistic attitude than rats in predictable environments.

Research has shown that right-handed people are more likely to be optimists, and lefties are more likely to be pessimists. This fact is so well-known I don’t feel obligated to cite it. When I learned this 12 years ago, I set out to test whether horses have cognitive biases and whether the hair whorl could predict it. I may be the first to test whether horses with left-sided whorls versus those with right-sided whorls differ in cognitive bias. I experimented on my horses (unpublished results), but I did write about it in Chapter 7, “Genetics and Horse Behavior (Equus caballus), by Mark J. Deesing and Temple Grandin.

I had two Warmblood mares a few years back, Bob and Sam. Bob had a high left-side hair whorl, and Sam had a high right-side hair whorl. Both mares were six years old and shared the same sire but different mothers. I bred, raised, and trained both mares himself. Their shared environment was the same; both had free access to pasture year round and access to large lean-to sheds in a 30 by 40 meter fenced corral for shelter in the winter. Sam and Bob were both reactive to sudden novelty and social separation; however, Sam (right whorl) vocalized more when separated and attempted vigorously to return to the herd. Sam also nickered and whinnied more than Bob at feeding time. The emotional responses to positive and negative stimuli between the two were evident from when they were born. For the cognitive bias test, I used a method described by Austin & Rogers in Asymmetry of flight and escape responses in horses—Asymmetries of Brain, Behavior, and Cognition, V. 12 (2007). First, I separated the horses and put them one at a time in my large corral to remove any distractions. I placed a grain bucket in the paddock’s center and let them eat from it one at a time; then, I moved 10 meters (30ft.) back near the gate, where I had an umbrella set on the ground. Bob was the first to go. I waited until she was facing me with her head in the grain bucket, then I walked suddenly toward her about 5 meters (15ft), lifted the umbrella pointing toward her, and suddenly popped it open. Suddenly startled, Bob turned to the right in flight (coinciding with her left side whorl); Bob retreated about 10 meters (30ft) back, then turned to watch as I returned to the gate. She was frightened with her head held high but stood and stared at me as I timed the latency period before she returned to the grain and finished it. It was just under three minutes.

When I repeated the experience with Sam, she turned to the left in flight (coinciding with her right side whorl), retreated about the same distance as Bob but was restless and looked like she was ready to flee again any second as I moved back to the gate to time the latency period before she returned as I waited for her to return to an almost full bucket of grain. Her eyes were wide, and the whites of her eyes (not noticed in Bob) were visible from 15 meters away. Her apparent fear was evident by the flared nostrils and the snorting sound of hyperventilation. I timed the latency period for her for about 15 minutes before stopping the stopwatch when she refused to return to the grain. She was a grain hog, too, so I knew her emotional reaction overrode her glutenous behavior to grain or carrots. During the daily feeding times, Sam was always the first to vocalize with whinnies at near dawn when they saw me walk toward the barn from the house. Her whinnies turned from quiet whinnies of predictability to wretchedness and desperation of uncertainty if I was ever late for breakfast. She was the queen of drama queens.

The emotional arousal in Sam was utterly absent in Bob. In the days after, Bob never showed any adverse reactions toward me, but Sam’s head went up whenever I was out about the barn and wouldn’t let me walk up to her as I had always done. I had to walk slowly and coach her to let me catch her while she kept looking to see if I had something unfamiliar in my hands. It saddened me, and I went out of my way for two weeks to regain her trust in me with treats and belly rubs. She always loved how I scratched her under the dock of her tail and along the side of her vulva. I always scratched away the crusties that built up there. That specific attention always overrode carrots or grain.

Sam was like many left-handed people, prone to depression. Left-handers are significantly more likely to have depressive symptoms than right-handers. As I said before, right-side whorls favor the left lead; in human terms, she was left-handed.

Lesley J. Rogers is a neurobiologist and emeritus professor of neuroscience and animal behavior at the University of New England. In a journal article titled; Relevance of brain and behavioural lateralization to animal welfare, Applied Animal Behaviour Science, V. 127 (2010), Dr. Rogers stated, “When assessing animal welfare, eye preferences for viewing certain stimuli may be a useful in species with laterally placed eyes.”

A right-side hair whorl indicates the dominant brain hemisphere, predisposing Sam to poor welfare in the wrong hands and those unaware of hair whorls. Even worse, horses with left brain dominance (left-side whorl optimism) would rely predominantly on processing by the right hemisphere in stressful situations. Not only would a stressful life history demand processing by the right hemisphere, but also chronic stress maintains the dominance of processing by the right hemisphere. Supporting evidence comes from evidence from Siniscalchi et al. (2014). Is the left forelimb preference indicative of a stressful situation in horses? Behavioral Processes, Volume 107, pages 61-67.

Now I’ve exceeded my 1000 word-post limit by 154 words, the five minutes of attention time most humans have, or I’d explain this further.