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Dogs can understand the differences in human facial expressions - and they don't even need a who

Researchers found that dogs were able to discriminate between angry and happy faces – when only shown half of a face. This was tested by training the dogs to tap a touch screen with their nose when they saw either happy or sad portions of human faces. Each time the dog made a correct response – correct being either the happy or sad face portion, depending on group – they received a treat! Over time, the dogs would consistently choose the partial emotional expression they had associated with treats, to get more treats! This research supports the idea that dogs can understand changes in our expression based on emotion. If your dog seems to react differently when your emotions change, they are likely able to detect these small facial expression changes like the dogs in this study.


In order to definitively understand if dogs truly comprehend differences in human emotional expressions, it’s important to uncover the basics of expression recognition. Fellow dog scientists did just that – using operant conditioning, specifically positive reinforcement based-training, to uncover canine ability to recognize small differences in human facial expressions. This is similar to the type of training you might have done with your dog to teach them to sit - rewarding them with treats when they perform the desired behavior.

Dogs entered a box-like experimental area, where they faced two touch screens with images. The dogs were able to be trained, through receiving treats for correct responses, to choose only images associated with a specific emotion. Even more impressively, they were trained to understand emotional differences in either the top or bottom half of the face only. Importantly, only 11 out of 18 dogs recruited reached the learning threshold. This might mean those 7 dogs did not understand the experimental design, or that not all dogs have the ability to understand emotional differences at this level.

The dogs who passed the training phase were then tested more thoroughly to be sure that they were choosing the images based on emotional expression, rather than some other unknown factor. These additional trials support that the dogs in their study seemed to understand expression differences produced by angry or happy emotions! The researchers discuss how this ability to understand the emotional expressions is probably due to their life experience living among humans. Learning to understand our facial expressions is important for dogs – it allows them to recognize the cue of an emotion and then anticipate a behavioral response from us. Since our dogs live with us every day, it is advantageous to them to understand certain facial or body language cues so they can better understand how to behave socially in the family unit. The same social monitoring occurs in humans and other animals!


Where to find the article: Müller, C. A., Schmitt, K., Anjuli, L. A. B., Huber, L. (2015) Dogs Can Discriminate Emotional Expressions of Human Faces. Current Biology, 25, 1-5.5.

Thanks to @sharpeiowen for letting us use their image. Follow them on Instagram!

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