Intimacy is not an immutable talent. Rather, it is a journey. Like other dexterities, it hones itself by trial and error. Intimacy means to enact, rehearse and polish modes of connection. Each time we begin to establish a relationship, we have a chance to learn how to be intimate, in both the short and the long term. Whether the union lasts for a few months, decades, or a lifetime, the refinement requires time.

Time is a dimension intrinsic to the exploration of the mind, but how the mind, or the brain, keeps track of time, and how we subjectively perceive it in a broad range of events and situations is still an open question. Since the 1800s, studies of mental chronometry have assessed the time course of mental events. These studies have mostly concentrated on measuring variation in people’s reaction times in the context of cognitive tasks of various degrees of difficulty. The consideration of a temporal dimension in the unwinding of interpersonal and emotional routines is equally crucial, but is a relatively recent addition to laboratory investigation. Techniques such as functional magnetic resonance imaging (or fMRI for short) have been extensively employed to map emotions on the geography of the brain. However, there is not a one-to-one correspondence between a given emotion and one area in the brain. The overall activity connected to each emotion is shared across networks of regions that work in parallel. One region may be more prominently engaged in a particular emotion, but at the same time will assist and underlie the processing of others. In this mesh of networks, coordinated time dynamics is paramount. What counts is not only the magnitude of an emotion, but also its temporal width, or how long it takes to reach or lose a certain degree of its intensity.

Our emotional life and our social interactions unfold across several time scales. When interacting with others, we observe, we perceive, we act, we remember, we imitate, we share, and we forget. Possibly, we adopt, change or abolish habits. Things happen in the order of sub-milliseconds, minutes, hours, days and weeks – even months and years. From the oscillation of neural waves to a rush of electricity across nerves, from the expulsion of neurochemicals to the acceleration of breathing, and from the proliferation of neurons to epigenetic tagging on DNA, the physiology of togetherness plays out at different speeds. It takes less than an instant to scan or mimic a facial expression. Angry or joyous reactions can peak in a matter of seconds. But for our mood to mount or sink, it may take a few minutes. The abolition of an undesired automated behaviour may take years. We could ask: how long does it take to really get to know someone?

Every individual has their own time scale as part of his or her emotional style, which is in turn an outcome of genetic composition and biographical experience. In a pair, these two scales will meet, compare and adjust. This involves comprehension and acts of will. If we take a couple called Aidan and Carrie, for example. Aidan is faster than Carrie at initiating or recovering from an argument. While he would forget easily, Carrie mulls over details for days. On the other hand, Carrie is fast at picking up his mood, while Aidan occasionally needs explanations for her words or actions. 

In an effort to uncover individual differences in emotional style and reactivity, research has begun to look in detail at temporal dynamics in connection to distinct personality traits or conditions. For instance, neurotics – who have a tendency towards negative emotionality and to persevere in it – take longer to recover from the spasm of an upsetting event. The part of the brain that engages in the action of coping with that event – the amygdala, to be precise – shuts down more slowly. Similarly, when we are depressed, our amygdala may take ten or fifteen extra seconds to recover from the effect of being exposed to words related to a negative mood.

We may wonder how long then does it take to build intimacy? The answer to this question will greatly depend both on the degree of closeness and the individuals involved. Intimacy grows from the loyalty and dependence that arise from an extended shared history of behavioural and emotional familiarity. The whole endeavour takes effort.