ABSTRACT
The core concept in this paper is the psychological present, commonly understood as a time interval in which sensory information, internal processing, and concurrent behavior appear to be integrated within the same span of attention. Understanding the relation between the temporal structure of input information and the processes that determine the dynamics of the present will also make it possible to understand the way in which conscious temporal experience (time perception) is shaped.
The present, in this conception, is a highly flexible tuning process that is dynamically fitting the temporal width of the field of attention and its phase relations to the sequential structure of the pattern of events. Thus, it serves an important function in enabling the organism to optimalize its information processing activities. It is an active, or constructive process; this necessitates the assumption that temporal information can be extracted from event sequences that is structurally independent of the nontemporal dimensions of information (viz., spatial and categorical attributes of stimuli).
Because the present is so highly adaptive, no fixed parameter values can be expected to describe it adequately. Only under certain boundary or rest conditions may we expect the parameters of the process to adopt certain values, related to the properties of the information processing mechanisms (scanning rate, precategorical storage, STM, etc.). Some of the procedures that the organism has available for extracting and parsing temporal information have become known in recent years, and some attempts at formally describing these procedures have been made. At the same time, there is some psychophysiological evidence to support the view that the tuning process may be controlled by phasic changes in alertness and allocation of effort.
This conception of the role and significance of the present adds a new dimension to the age-old problem of the subjective flow of time. There is a considerable argument about what causes subjective time to accelerate or decelerate. While it is fairly common to attribute such changes to the number and complexity of events or to the processing effort involved, some contradictions remain.
