When our brows go up, it widens our eyes and gives us a broader field of visionâthe surprise brow is our bodyâs way of forcing us to see more. We may also do a double take to make sure that we saw what we thought we saw. By way of contrast, when weâre angry our eyes narrow so that we can focus on a known problem. In addition to making our eyebrows rise, surprise causes our jaws to drop and our mouths to gape. Weâre struck momentarily speechless. Our bodies temporarily stop moving and our muscles go slack. Itâs as though our bodies want to ensure that weâre not talking or moving when we ought to be taking in new information.