As a horse trainer, I often hear stories about "stupid" horses, or an owner commenting that a particular horse is not the sharpest tool in the shed. In fact, Google or YouTube "stupid horse" and you get a heck of a lot of results. Yet I haven't met a single horse yet whom I would classify dumb. Which got me to thinking. Is it intelligence people are rating, or is it actually just trainability?
I've seen horses do some pretty intelligent things, including things that pretty clearly required reasoning. I've also worked with some horses who seemed to have practiced what I taught them the day before, overnight - they performed what I asked, what they'd just learned, flawlessly the next time I asked. So how much can be attributed to trainability and how much is intelligence? It can be difficult to differentiate at times. In the mean time, some examples of trainability:
One horse I work with, a Thoroughbred, I thought maybe really was the first dumb horse I'd ever met. Until he actually did learn a few tasks exceptionally quickly. Which caused me to think, and re-evaluate. He learned so fast because he was in a setting he enjoyed, where he wanted to learn. When motivated, he is very responsive (notices every detail in my body language) and is an extremely quick learner, but when he isn't, he just doesn't even try (I think his young age and thus maturity level definitely has something to do with it as well). Which is why he never made it as a racehorse...it was never a problem with intelligence, just with trainability.
Another example is a mare I currently work with - very independent. I was working her in an outdoor ring until just recently, and she didn't seem to be picking up on things. This is a mare I know is brilliant, as I have worked with her previously - she has blown me away with her intelligence and/or trainability. Yet she just wouldn't learn and seemed to even have forgotten previous things I had taught her - so frustrating! Instead of focusing on what I was trying to tell her, she was so focused on extrinsic distractions. So I took her away, moved her into a small pen away from her old, distracting, friends, and started working her in an indoor arena. Suddenly she "remembered" what she'd previously "forgotten" and she was learning all sorts of new things. She'd always been smart, and her trainability skyrocketed in a different situation.
There are enough stories out there where horses have used reasoning and obvious intelligence to help their human or horsey friend, to get help, to let us know they are sick or hurt, and to do simple tasks such as open stall doors or otherwise solve a puzzle, that I don't think we can question the intelligence of the horse as a whole. In my experience, I have yet to meet a stupid horse and I honestly think such a horse is rare - perhaps one example could be a horse deprived of oxygen at birth and thus experiencing brain damage.
I think as well that our perceptions of why horses do the things they do also plays a role when we're evaluating a horse's intelligence. We're human, predators, and to boot, we're not in that particular horse's head. So we really have no idea what they're thinking - why they might do certain things. I think a lot of times people make assumptions about a horse's intelligence without looking at things from the horse's perspective. Maybe the horse is indeed intelligent, but just doesn't want to learn, or is just doing something because he's a horse. On a related note, in my opinion a person's assessment of a horse's intelligence is determined also via that person's training approach or methods. The trainer with the right approach for that horse might experience a great deal of success and thereby reveal the intelligence of a horse, whereas the trainer with the wrong approach for that horse might experience little success and thus draw the conclusion that horse lacks intelligence. This means a horse's level of trainability and the trainer's approach will both play a role in the determination of a horse's level of intelligence.
Here are some links to check out as they pertain to equine intelligence:
Testing Equine Intelligence - From Horse & Rider
The Thinking Horse - Cognition and Perception Reviewed, Evelyn B. Hanggi, MS, PhD