Dogs, Humans, & Rhesus Monkeys Read Human Faces Same Way

happyfaceScientists have shown that dogs use the left gaze bias to look at human faces. Left gaze bias means the right side of an object is inspected first and for a longer period of time.

  • Adult humans show the bias only when looking at human faces that are right side up.
  • Infant humans show the left gaze bias when looking at objects, faces of any species, and faces in any orientation.
  • Rhesus monkeys show the bias towards upright faces of monkeys and humans.
  • Interestingly, dogs only show the left gaze bias when looking at human faces, whether the faces are upright or inverted.  Dogs don’t show the bias towards objects or dog faces.

This suggests that left gaze bias may be an adaptive trait that aided dogs in developing their successful relationship with humans.