Question 1 - Writing and Language Practice Test for the PSAT/NMSQT^® Exam

For the first time horses have been shown to be able to distinguish between angry and happy human facial expressions. Psychologists studied how 28 horses reacted to seeing photographs of positive versus negative human facial expressions. When viewing angry faces, horses looked more with their left eye, a behaviour (1) coupled with perceiving negative stimuli. Their heart rate also increased more quickly and (2) they will show more stress-related behaviours. The study, published today (10 February) in Biology Letters, concludes that this response indicates that the horses had a functionally relevant understanding of the angry faces they were seeing. The effect of facial expressions on heart rate has not been seen before in interactions between animals and humans.

(3)Amy Smith; a doctoral student in the Mammal Vocal Communication and Cognition Research Group at the University of Sussex who co-led the research said: “What’s really interesting about this research is that it shows that horses have the ability to read emotions across the species barrier. We have known for a long time that horses are a socially sophisticated species but this is the first time we have seen that they can distinguish between positive and negative human facial expressions.”

“The reaction to the angry facial expressions was particularly clear - there was a quicker increase in their heart rate, and the horses moved their heads to look at the angry faces with their left eye.”

Research shows that many species view negative events with their left eye due to the right brain hemisphere’s specialisation for processing threatening stimuli. (4) (Information from the left eye is processed in the right hemisphere.)

(5) Amy continued: “It’s interesting to note that the horses had a strong reaction to the negative expressions but less so to the positive. This may be because it is particularly important for animals to recognise threats in their environment. In this context, recognising angry faces may act as a warning system, allowing horses to anticipate negative human behaviour such as rough handling.”

(6)However, a tendency for viewing negative human facial expressions with the left eye specifically has also been documented in dogs.

The horses were recruited from five riding or livery stables in Sussex and Surrey, UK, between April 2014 and February 2015. (7) They were shown happy and angry photographs of two unfamiliar male faces. The experimental tests examined the horses’ spontaneous reactions to the photos, with no prior training, and the experimenters were not able to see which photographs they were displaying so they could not inadvertently influence the horses.