Any intense emotion such as excitement, attentiveness, curiosity – will make pupils dilated. Boosted emotion intensity, not necessarily positive or negative, will effect pupil dilation. Smaller pupils often stand for leisure, sleepiness, boredom.
Looking straight into eyes of a unfamiliar dog, most certainly is not naive. Direct eye contact is usually either a sign of domination, threat or even a cue for attack. A dominant dog that is being looked at in such a way, can comprehend staring as aggression, while a fearful one will get it as confirmation of its fears. Nevertheless, in some cases, especially with familiar dogs, it does not have to have the same meaning.
Turning the look away to avoid direct eye-contact is a sign of either submission, or desire to avoid conflict although with confirmation of other's domination, but it can also be a signal for fear, or simply a sign of boredom.
Eyebrows
Dogs do not have eyebrows, but they do have markings that emphasize muscle movement around the eyes. Brow-expression in dogs is similar to brow-expression in humans.
1. Anger – eyebrows are narrow, contracted and turned downwards.
2. Fear or submission – eyebrows are turned upwards in the middle, outer ends are turned downwards.
3. Interest and wonder – eyebrows are up.