Researchers from the University of Sussex and the University of Portsmouth did a study to see if horses could remember a humans emotions.
These horses were shown a picture of someone that was happy or sad then those same people came in. The people did not know what picture of them was shown to the horse so that they would act neutral when they saw the horse. The horses reacted differently to the people based on the picture they had seen. Some of the horses showed signs of feeling threatened if they were shown an angry picture. The horses did not react when random people came in that they had not seen pictures of.
This experiment worked because they were able to test whether horses could remember peoples emotions based on a picture, they concluded that horses were able to remember humans emotions because the horses reacted to the person based on the picture they were shown.
This relates to engineering because they created an experiment to test something and based on these results they can create new experiments.
This experiment shows that horses can remember human emotions and react to people different based on past experience with them.
https://www.popularmechanics.com/science/animals/a20094846/horses-can-read-and-remember-peoples-emotions/
