Showing posts from April, 2009

Time in Computation

This is the last post in the series Brain - Time - Music - Computing . Previous: Time and the Brain The notion of computation was explicitly created for use outside of the flow of MWT. Models of computation provide primitives for describing processes in a purely timeless context (computability), or in an artificial and abstract flow of time marked by computational operations (algorithmic complexity). The resulting abstract manifestation of time in computing is enforced as a strong invariant, universally and implicitly relied upon. This state of affairs has serious implications for the design and use of computing artifacts in MW. Music exists at the confluence of creation, representation and performance, where inherent limitations of time representations in computation become evident. Music systems fall into two broad categories: online or real-time systems, and off-line system. The significance of these categories in the context of interaction is explored in [1]. Henkjan Honing more speci

Time and the Brain

This is part 4 of 5 in the series Brain - Time - Music - Computing . Previous: Time and Perception Next: Time in Computation If the flow of MWT is immutable, the human brain hardly perceives it as such. Gooddy, in his book Time and the Nervous System [3], distinguishes between Personal Time (PT) and Government Time (GT). The former marks the flow of time (MWT) as perceived by the individual brain; the latter refers to the passage of time as measured by a collectively recognized reference clock, from the brain’s perspective an external synchronization device to MWT. Alteration in the perception of time, of the flow of one’s PT, occur within the perceiving agent’s mind. Fraisse emphasizes the necessity to separate the perception of duration, which takes place in the psychological present, and the estimation of duration which “takes place when memory is used either to associate a moment in the past with a moment in the present or to link two past event” [2]. Memory frees the mind from the c

Time and Perception

This is part 3 of 5 in the series Brain - Time - Music - Computing . Previous: The Brain in Middle World Next: Time and the Brain Scales of time in MW play a crucial role in the recognition and interpretation of temporal patterns, by the brain, as symbolic relationships such as causality and synchrony. Events that are perceived as shortly following each other in time tend to be interpreted in a causality relationship. Brains learn the range of latencies that may separate an action and the perception of its effect in MW. The quantitative characterization of acceptable latencies is crucial to the understanding of interaction. Human-computer interaction researchers [4][1] categorize acceptable time delays into three orders of magnitude, which coincide with Newell’s cognitive band in his time scale of human actions [5]: the 0.1s (100ms) scale characterizes perceptual processing, perceived instantaneous reaction; the 1s scale characterizes immediate response, continuous flow of thought (cons