The specious present (biology)
The experience and perception of time is discussed by Le Poidevin (2015).
We see colours, hear sounds, feel the effects of gravity, and are aware of temperature – all through our senses, but how is time perceived? Though we may think of time-perception in relation to change, the non-simultaneity or order of events, or the ideas of past, present and future – it is probably duration that is most obvious.
So how and where, then, do we sense duration?
If we imagine counting the ticks of a clock as a way of marking duration then our awareness of time lapse as something that is mind-independent (the ticking of a clock) is registered in our brain in the form of some kind of memory trace. It is as though the longer ago an event occurred the weaker is the trace, thus giving us a measure of duration. Successful estimation of time intervals is present across the animal kingdom.
In an interval of any duration there will be earlier and later parts, a past and a present. This suggests that the present, now, must be durationless. Considering the finite speed of both light and sound it appears that we can only ever perceive what has past but we are adapted to experience only the very recent past, except when we are star-gazing.
As soon as we become aware of the present it has become past. When we listen to a piece of music we seem to retain notes or phrases in our heads as a brief memory, so that within our subjective present we can enjoy the sensation of a combination of successive notes, not just each note as an individual and separate experience. If we are familiar with the music then within that present moment we may also eagerly anticipate a few notes to come. The same applies when we listen to a spoken sentence. In this way our subjective present may incorporate parts of both the past and future. There is no precise answer to questions about the length of our perceived present and that is presumably why it has become known as the ‘specious present’. In a loose and general sense we can regard the specious present as that brief period of time in which we react to objective external stimuli, say our response-time when driving or playing table tennis. Presumably the duration of the specious present relates to our short-term memory and assorted mental processing including brief memories and anticipations that take place before we become aware that some particular perceptions are being replaced by others.
Human and animal perception of time is a matter for empirical science. In the case of human beings it is studied as mental chronometry in experimental psychology. Mental chronometry records brain response times to various percepts under many conditions. If we take our response time when driving as an example of the specious present then it is about 1.5 seconds, and for a responding click on a smartphone it is about 0.3 seconds.
There are obvious psychological constraints to what we can encompass in our present. We do not see the rapid refreshing of a TV screen or the individual pictures that make up a celluloid movie although we know that they exist. This suggests a possible connection between our sense of duration and our vision.
Now as an evolved adaptation
Each animal species has a set of senses as evolved adaptations that are a consequence of that animal’s historic environments. Collectively these senses determine the perceived reality of that animal’s world. We can determine to some extent the range of the senses of animals, their sensitivity to smell and so on. Though we cannot experience what they experience we have some idea of the nature of their sensory world. Clearly the experienced reality of a herring is
different from that of a bird or human being. We also know that the perceived reality of humans, unaided by technology, is not privileged over other species: birds see better than us, dogs have a more highly developed sense of smell and hearing, whales hear better underwater and so on. One feature of our senses is that they sample only part of what it is possible to sense. Humans hear and see within a limited range of what it is possible to hear and see, since we use only those waves of sound and light that aided our survival in the past. In a similar way we are biologically attuned to the range of time durations that were of adaptive value to us in the past. A cloud of bats flying inside a cave, in order to avoid collision, must be much more finely tuned to short time intervals than us. It seems reasonable to suppose that time-sense will be roughly related to factors like body size and energy expenditure.Many organisms respond far more rapidly than us to changes in their environment. There is little doubt that the length of our human specious present is a biological adaptation that allowed us to respond effectively to stimuli and threats in our historic environment. The specious present (largely unconscious) will also be different for different animals since many animals respond to time lapses are imperceptible to us.
Our interest is in the implications of the specious present for the philosophy of time. We can conclude from the above that the period of time we generally refer to as ‘now’ is not the perception of a universal now but a biological temporal adaptation unique to the human species and loosely indicated by our reaction times; it is our human perceptual time-reality. Our human specious present will be of different duration to that of other animals and it is not privileged over theirs, it is simply a consequence of our own particular evolutionary history – just as the colours we see and sounds we hear are different from those of other animals. We accept the limitations of out spatial perception, acknowledging that many animals perceive space in different ways from us, discriminating shorter or longer distances, but we find this difficult to accept for time which we feel must be the same for all creatures.
The brain as a temporal sense-organ
Time is not generally included as one of our senses, perhaps this is a shortcoming. There seems no reason why our human sense of time should be considered any different from our other five senses of touch, taste, sight, hearing, and smell. Unlike other senses time-sense does nothave a dedicated sense organ: maybe it is an integration of the other senses as a brain process. Another difficulty is that our five of touch, hearing, sight, sound and smell all responding to physical stimuli: smell molecules, light waves, sound waves and so on. What physical object are we sensing when we sense time? How do we perceive time?
The dynamic quality of time
Perhaps we do not sense time itself but other things? Now seems to be constantly changing as new experiences are perceived and processed in our brains. If our brain is acting like a sense organ then we sense not only a fixed term present or now that lasts about 0.3-1.5 seconds but also a now that is constantly changing and hence our sense of ‘lapse’. How can this be explained? If the lapse (flow) of time is a subjective matter then it requires psychological explanation? There is no shortage of possibilities:
• The lapse of time from future, to present, to past with its associated changing facts and truth-values has the feeling of movement
• Spatialized language of time (watches ‘running fast’, time ‘passing by’ etc.) implying the movement, spatial extension and contraction, varying temporal intervals expressed like distances or lengths, even the temporal accretion of facts and events – all suggest movement
• The arrow of time with its language of directional movement ‘forwards’ and the impossibility of time going ‘backwards’ suggests spatial movement in a direction
• Our perception of change, succession, and continuity are all reminiscent of spatial movement
• Physical objects and events seem to pass into, through, and out of existence, and for anything to change it must become older
• The incessant processing of information in the brain also suggests continuity
The specious present: past, present, future
We might say that the future is anticipation and the past is remembrance. Philosopher of time Adrian Bardon from Wake Forest University describes it as psychological projection that is indispensable for us to maintain a coherent reprsentation of the world. He notes Kant‘s observation that mental recollection of its nature must entail past and present, that we have an innate sense of temporal succession, and that space and time are necessary mental constructs constraining our spatial and temporal perception to ‘here’ and ‘now’, adaptive ideas without which we could not survive: we must impose order on the world whether it objectively exists or not.
Perhaps we can understand the temporal perspectival subjectivity of past, present, and future by using the spatial perspectival analogy of my computer being ‘here’ and your computer being ‘there’ while for you this situation is reversed.