Temporal Displacement and the Nature of Temporal Intervals

Temporal displacement (Zeitverschiebung) has been recognized since the dawn of scientific psychology. If subjects are asked to point at the place over which a pointer passes at the same time a synchronized sound is emitted, they seldom succeed in pointing at the right place. They often point at a place that is located either after the correct location of the pointer as the sound was emit­ted (positive displacement), or before the correct location (negative displace­ment). If the time required for visual and auditory physiological processing to be accomplished is taken as a norm to study the displacement phenomenon, it will be studied by comparing the physical time of stimulation with an alleged psychological time that should be reconstructed from the subjects’ reports. For this reason Vicario (1973a: 47-49) claims that the phenomenon is not studied as such and the conclusion must be that the instants of physical time are not coincident with psychological time, and hence that the reproduction of events in psychological time is in many respects discrepant with their succession in physical time. If, then, perceptual time is studied from this standpoint, the lack of correspondence with the physical measures of time leads to the positing of a psychological time, an alleged subjective time, while the order and the struc­tures of phenomenal time are not even recognized.

Benussi (1913: 7-14) shows that the temporal displacement is not an error due to the discrepancy between phenomenal and physical time. This claim assumes that both measured and perceived time consist of instants, which are their minimal elements, and that perception of time reproduces physical time with subjective distortions. Instead, time perception involves phenomenal structures that usually underlie a correct localization of events in time, even though the short duration of events in the displacement gives rise to a phe­nomenon that can be said to be paradoxical only in comparison with the ob­servation of the stimulus sequence. Phenomenal time consists of qualitative structures delimited by boundaries that can be put into correspondence with intervals measured in physical time but are still distinguished by their inherent qualitative nature. Benussi calls present (Gegenwart) the middle scale struc­ture from which phenomenal time is articulated and holds that there are other temporal structures that are extended in reference to it as non-independent parts thereof. Then, phenomenal time is not the succession of minimal units, that is instants, which follow one another. It consists of structures that are uni­tary temporal intervals as well as of relations according to the dependence of the structures on one another.

Each kind of temporal interval has an intrinsic meaning because it is a phenomenal structure, namely a delimited and unitary temporal extension rather than a simple discontinuous change. The unitary character of the intervals does not derive from comparative judgements, memory, atten­tion or even a number of subjective acts that identify and collect temporal points. These intervals are indeed “absolute” structures with qualitatively different boundaries. They are: very short intervals (90-234/252 msec.); short intervals (234/252-585/630 msec.); indeterminate intervals (585/630-1080/1170 msec.); long intervals (1080/1170-2070 msec.); very long intervals (beyond 2070 msec.). These intervals build the time of presence (Presenzzeit), that is, the temporal extension that is grasped in all its partial structures together by a single act of perceptual attention. The section of the time of presence whose duration is coincident with one of the lowest boundaries of the very short interval (about 100 msec.) is the phenomenal present (Gegenwart). It is the temporal segment whose appearance is so conspicuously forced upon subjects that it excludes the simultaneous discrimination of any other seg­ment (Benussi, 1907: 445). Benussi explains the qualitative difference of these intervals through the grouping of events with distinct temporal positions. Below 90 msec., two successive events delimiting a temporal segment, for example two tones, appear simultaneously as one unitary event whose ini­tial and final ends are not perceived. The proper temporal intervals occur be­yond this value. In the short intervals the delimiting events are not perceived as separated from one another and from the temporal interval. The sub­jects do not perceive the temporal segment but rather the succession of the boundary tones. In the long intervals, it is difficult to perceive the tones as boundaries enclosed in the temporal segment they delimit. Finally, the inde­terminate intervals are the smallest temporal segments in which the greatest number of disconnected elements or a unitary change may be perceived. This means that for events with indeterminate interval duration, the perception of boundaries is balanced against the perception of the temporal segment extension.

The properties of temporal intervals derive from the grouping of events that fill the temporal segment differently, that is with distinct perceptual roles that emerge with different degrees of conspicuousness (Auffalligkeit; 1913: 37; see Antonelli, 1994: passim). For example, given three horizontally collinear and equidistant dots A, B and C, their perception in the left-right direction makes the distance A-B appear shorter than the distance B-C (1909: 74). Be­nussi claims that A-B are grouped together against C, so the subjects perceive a whole in A-B and an intermediate space between the two dots B and C, for B is a boundary of the whole and is detached from C. The dots of the pairs fill their places differently: A and B are conspicuous boundary points of the whole, the span B-C is conspicuous as the extension between A-B and C. Therefore, distinct features characterize the dot pairs: in A-B, the qualitative diversity between the boundaries and the whole; in B-C, the spatial distance whose phenomenal magnitude amounts to the extension separating the whole from C (the distinction between diversity and distance is due to Meinong (infra § 7.4); the notion of a phenomenal magnitude derives from Brentano).

Likewise, the grouping of events in time brings about a different localization of temporal points, which underlies the perception of their duration. If three tones are presented at equal intervals, the grouping of the first two for their similarity gives rise to a whole auditory object whose duration accordingly ap­pears shorter than the temporal segment occurring between the second and the third tone. In the first tone pair the connection between tones is conspicu­ously forced upon the subjects, while the third tone is perceived as an outer boundary of the time segment that separates it from the other two. The be­longingness of tones underlies the perception of the delimited interval whose duration depends on either temporal diversity or distance. Benussi maintains that the more conspicuously the events are grouped as parts of something fill­ing time, the less the time itself appears. The interval is perceived as the du­ration of something according to the diversity of its boundary rather than as a temporal segment whose extent amounts to the distance between its ends. For example, if the first of two successive tones has a greater loudness than the second, it appears to fill a greater number of points of the delimited in­terval. Consequently, it shows a longer apparent duration and the interval, of which it is the initial boundary, appears shorter. If the second tone has a greater loudness, its perceptual duration is longer and the interval, of which it is the end boundary, appears longer (1913: 272-339). On the other hand, the less the events unfolding in time appear as parts of a whole belonging to one another, the more the time appears as a perceptual object itself (1913: 327k). Therefore, Benussi shows that phenomenal time is a form of order that emerges in con­nection with the grouping of events. Accordingly, temporal displacement is a consequence of the nature of perception instead of an illusion or an error. The displacement derives from the fact that subjects perceive the mutual temporal position of events rather than simple temporal points or empty intervals. Be­low definite temporal values, the conspicuous features of the events directly determine the points, hence the order of the temporal succession. For short in­tervals, the events are grouped in a unit that has time, rather than being in time, so that the more conspicuous event or part even precedes or follows the others in a perceived temporal order regardless of the succession in physical time.

Source: Calì Carmelo (2017), Phenomenology of Perception: Theories and Experimental Evidence, Brill.

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