The soft brush of fur against a bare calf – a familiar, almost imperceptible pressure – is, according to behavioural science, far more than a random feline gesture. When a cat winds between its owner’s legs, it is depositing scent from glands on its flanks and head, marking the person as part of its social group. It is a quiet act of identification, a compliment paid in a language humans are only beginning to decipher.

That language, psychologists say, is processed by the same cognitive machinery we use to understand other people. Nicholas Epley, a behavioural scientist at the University of Chicago, argues that the human brain does not operate separate systems for interpreting human and animal minds. Instead, it employs a single mechanism – what researchers call theory of mind – to imagine the thoughts, desires and emotions of any being it deems capable of experience. Over time, this leads owners to construct entire personalities for their cats: the jealous companion, the aloof observer, the playful schemer. The brain, in effect, builds an internal model of the animal and uses it to anticipate reactions.

Science is now cataloguing the outward signals that betray a cat’s inner state. A tail held upright like a flagpole signals friendly intent, the feline equivalent of a wave. A slow blink, research suggests, is associated with a positive emotional state and can be a sign of trust and contentment, akin to a human smile. Rolling over to expose the vulnerable belly is an ultimate gesture of confidence, though it is rarely an invitation for a rub – cats prefer to be stroked on the head and neck, and an attempt on the stomach often ends in a hasty retreat.

Even the notorious bite is being reinterpreted. Veterinarians note that many nips occur during a stroking session when the animal has simply reached its limit of tolerance and seeks to end the interaction. Others are so-called “love bites”, soft and harmless, delivered in moments of trust or play. The message is not aggression but communication: a request for space or a clumsy expression of affection.

A recent study from the University of Bari, however, suggests that cats may not be as attuned to the emotional content of human voices as their behaviour implies. When researchers played recordings of laughter, crying and shouting to domestic cats in their own homes, the animals consistently entered a moderate state of alertness – ears swivelling, pupils dilating, tails twitching – but their responses remained virtually identical regardless of the emotion conveyed. “Instead of distinguishing immediately between happiness, fear, anger or sadness, they responded with a generalised increase in alertness,” explained lead author Serenella d’Ingeo. “This may represent an adaptive strategy that prepares them to react quickly to a potentially relevant social situation.” The cat, it seems, perceives that something has shifted in its human’s demeanour, but does not parse the precise emotional note from the voice alone. The bond, then, is built not on a shared emotional vocabulary, but on a quieter, more patient exchange of signs – a head bump, a slow blink, the silent pressure of fur against skin.