A sense of time

We tend to take our sense of time pretty much for granted, as if it’s just part of what it means to be human. We’re aware when something is either too brief or taking a long time. Time passes all too quickly when we’re enjoying a ride at Disney World but drags when we’re waiting for a table in a restaurant. We get good at estimating temporal intervals, especially in familiar circumstances. If friends say they will show up in 30 minutes, we have a feeling about when to start looking for them. We can predict how long things are likely to take. Do we have time to stop by the store and still get somewhere on time? We know what five minutes feels like compared to an hour. And all of this without checking the time on our iPhone.

Telling time

Being able to tell time is not the same thing as having a sense of time, but as we will see it is probably a prerequisite. Knowing how to tell time is a matter of having learned how to talk about time in terms of temporal units. This involves more than the rudimentary skill of describing analog and digital clock indications in vernacular dialect. We expect this basic proficiency to blossom into the ability to talk with others in terms of temporal units. So we answer the question “What time is it?” by reporting that it’s ten-fifteen. We agree to meet someone in an hour. We say we have a meeting at one-thirty. We ask how long the movie is. We describe behavior with reference to temporal units, for instance by saying that it takes us twenty minutes to drive to work or that we got home yesterday at half past five or that our friend is already thirty minutes late.

In principle, we could learn to tell – talk about – time without acquiring a broader sense of time. In practice, this distinction does not emerge because as we are learning this verbal repertoire we are also developing what we call a general sense of time.

Temporally discriminated behavior

“Time is nature’s way of keeping everything from happening at once.” This quip, popularized by the physicist John Archibald Wheeler reminds us that our behavior is unavoidably distributed in time. This means that throughout our lives the passage of time accompanies the ceaseless flow of behavior-environment contingencies. It should not be surprising that under the right conditions these contingencies result in temporally discriminated behavior.

But what does this phrase mean? What we can observe is that certain behaviors are distributed in time in an organized and consistent way. Behavior analysts are especially familiar with this phenomenon in the context of schedules of reinforcement. Nothing brings the point home as clearly as watching a pigeon respond under a fixed-interval schedule of reinforcement. The characteristic scalloped pattern revealed in a cumulative record from interval to interval is iconic. It’s not hard to find non-laboratory examples of behavior that is similarly distributed in a more or less consistent temporal pattern. If you don’t have a watch, your behavior of checking the brownies baking in the oven will make you look much like that pigeon.

In trying to explain temporally organized responding, we can put aside those instances in which responding is controlled by supplementary stimuli. In one example, responding can depend on an external clock. This is a generic term for any stimulus that changes with the passage of time. This correspondence with time can result in responding coming under control of the supplementary stimulus. When pigeons can view a stimulus that systematically changes as the fixed intervals time out, responding tends to become more efficient, typically with a single response emitted immediately after the end of each interval.

Another example involves the influence of a verbal repertoire. Non-verbal humans show the same scalloped patterns of fixed interval responding as pigeons. However, participants with a verbal repertoire engage in self-instructional behavior, and their responding often looks like that of pigeons that have access to an external clock. These participants may covertly say to themselves that responding too soon doesn’t pay off but waiting a bit before giving it a try often does and is therefore a rule worth following. The result is that there may be little or no responding until the intervals expire.

Even when we put these supplementary sources of control aside, it’s obvious that behavior is often temporally organized. But what are the stimuli that control such patterns? What are the factors that produce responding that is distributed in consistent patterns over time? This is an interesting question, but it may not be the same as asking about a sense of time. Is the development of temporally organized responding what we mean when we refer to having a sense of time? Do pigeons have a sense of time in the way that we seem to?

Awareness of time

What is going on behaviorally when we sense anything? We understand that each sensory modality involves a physiological system that kicks into gear when stimulated. We are less familiar with the corresponding behavioral aspects of sensing, but they are critical to understanding what we learn through our senses. Our sensory systems enable us to experience all detectable stimuli, but we learn to respond to only those that are relevant to our behavioral needs at any moment. It’s a godsend that we don’t respond to all stimuli impinging on our receptors – we would be overwhelmed. Instead, we mainly respond to those stimuli that our learning history has made important. So when we’re driving our car, we pay attention to the visual stimuli (how close we are to other cars) that will get us safely where we’re going and don’t notice all the other stimuli (advertising signs) that are irrelevant to this outcome, even though they are very much part of what our eyes capture.

As Chapter 4 in the book explains, our responding to the fact that we are responding to events is what we generally call awareness, although we may also refer to it as perception or consciousness. The events we are aware of are those that we describe or tact. In fact, merely noticing an event for what it is involves tacting it, however casually. When we do so, we are responding to our own behavior, a skill that requires a particular verbal repertoire taught by a verbal community because it is socially useful. In other words, when we report that we can sense something, we are responding to our sensory behavior. We may sometimes only notice our sensory reaction privately, but this still involves tacting our own behavior.

This is relatively straightforward in the case of the behavior of seeing, hearing, touching, smelling, and tasting, but we don’t seem to have a sensory apparatus for detecting time. Nevertheless, there is no question that verbal humans learn to be aware of (respond to) the fact that time is passing as we behave, though it is a weak skill at best and we are imprecise, easily fooled, and often mistaken in our reactions. So what are we doing when we report that we are aware of how long our experiences last? As with the traditional five senses, we are responding to our own behavior, but there is presumably no sensory input or physiological experience uniquely associated with time to be aware of. Instead, we are responding on the basis of a history of merely observing our behavior in temporal terms in its environmental context.

In other words, our lifelong experience of being aware of our behavior is unavoidably paired with the passage of time. Along the way, we develop a modest skill of describing our behavior in terms of our time telling repertoire (our ability to talk about time). That is, we learn to describe behavior in terms of a temporal vocabulary. When we guess that we’ve only been waiting for about ten minutes or say that something is taking a long time, for example, we are not responding to the behavioral impact of environmental stimuli on a unique sensory apparatus, as when we say that we are seeing something. We are, in effect, saying that we’ve been behaving for a certain period of time. We are assigning temporal labels to our experience of our own behavior.

We should expect that this repertoire is less well developed in cultures that lack a means for measuring time precisely, and it is entirely absent in non-human species. Dogs, for example, do not have a sense of time because lacking a verbal community they have no means of acquiring a self-descriptive repertoire in the first place. Our family pets are neither aware of their behavior nor its relation to time. Although their behavior is often temporally organized as described above, they do not learn to respond to their behavior as we do by feeling that something is taking a long time, for instance. When we leave our dog in the house but realize before we get to the end of our street that we’ve forgotten something, our dog reacts to our return only a few minutes later in the same way it does when we’ve been gone all day.

In sum, neither talking in terms of time (time telling) nor temporally discriminated responding is what we usually mean when we refer to having a sense of time. The vernacular reference to sensing time is a matter of being aware of (responding to) our behavior in temporal terms, whether specific or vague. We do not directly sense time physiologically, as we do visual stimuli, but learn to describe our behavior (sometimes only in a private reaction) in a temporal frame of reference. When it seems that we are “sensing” time, we are reacting in terms of a temporal vocabulary to a long history of correspondence between our ongoing behavior in various situations and the passage of time.