Dogs respond to human attention with a precision that other domestic animals do not match. The ability appears early in development and does not require training to emerge.
Gaze direction is the primary cue
Dogs follow the direction of a person's eyes and head, and they use that direction to locate food, objects and the focus of a person's interest.
Human eyes are unusually visible, with a pale sclera surrounding a dark iris, which makes gaze direction readable at a distance in a way it is not for most species.
Dogs also check a person's face before acting in ambiguous situations, a referencing behaviour that closely resembles what young children do.
Behaviour changes with whether they are watched
Dogs told to leave food alone are substantially more likely to take it when the person's eyes are closed, turned away or otherwise occupied.
This is not evidence of deceit so much as evidence that the prohibition is understood as conditional on attention, which is how it was usually enforced.
The same mechanism explains much of what owners describe as sneaking, since the dog is responding to a cue that the constraint is currently inactive.
The guilty look is a response, not a confession
The lowered head, averted gaze and flattened ears that owners read as guilt appear reliably when a person is displeased, whether or not the dog did anything.
Studies that separate the two find the display tracks the owner's behaviour rather than the dog's prior actions.
The expression is therefore appeasement directed at a signal being given now, not recall of an event that happened while the owner was out.
Pointing works for dogs and not for most species
Dogs follow a human point to a hidden container from a young age, including forms of pointing they have not encountered before.
Wolves raised with intensive human contact perform less well on the same task, which suggests the ability relates to domestication rather than to socialisation alone.
Communication also runs both ways, since dogs alternate their gaze between a person and an inaccessible object in a manner that functions as a request.
Practical consequences for training
Because attention is the operative cue, commands given while looking away carry less weight, and inconsistency between watched and unwatched conditions teaches conditionality directly.
Timing matters for the same reason. Responding to something found later gives no usable information, since the dog links the reaction to the present situation.
Training that relies on the dog's attention-reading tends to work faster than training that assumes the dog is applying rules independently of who is present.