Vierordts Law Of Time Estimation See Vierordts Laws

VIERORDT'S LAWS. There are two separate usages or versions subsumed under the same eponymic principle called Vierordt's law, both of which are attributable to the

German physiologist Karl von Vierordt (18181884). One usage is related to the study of sensory thresholds, and the other usage refers to the area of time perception. In the first case, Vierordt's law is the proposition that the more moveable a part of the body is, the lower is the two-point threshold of the skin over it. Thus, the two-point threshold decreases (i.e., increased tactile acuity) as one goes from the acromion/shoulder blade to the tips of the fingers. In other terms, Vierordt's law of outward mobility in the area of sensory psychology states that tactile acuity increases with increased mobility of body members. However, although Vierordt's outward mobility law appears to be true, generally, for the upper extremity, it is not as clearly applicable to various other body areas (cf., Greenspan & Bolanowski, 1996). In the second case, Vierordt's law of time estimation is the principle that short temporal intervals tend to be overestimated and long temporal intervals tend to be underestimated. Also, in this context of time perception/estimation, the concept of the in-difference interval is defined as the intermediate length of time that is neither underestimated nor overestimated. Based on this early general law of time estimation by Vierordt in the late 1800s, subsequent research in the area of the psychology of time has determined that the overestimation of short durations and the underestimation of long ones is as valid for "filled" durations/intervals as for "empty" durations/intervals. Thus, in turn, and ground-ed in Vierordt's law of time estimation, psychologists today study the effect of the different forms of "filling" a temporal interval (ranging from the use of short, discrete auditory tones to long, more continuous and meaningful narratives/events/materials) on one's perceived duration and estimation of time. See also FRAISSE'S THEORY OF TIME; GUY-AU'S THEORY OF TIME; SOMESTHESIS, THEORIES OF; TIME, THEORIES OF. REFERENCES

Vierordt, K. von (1868). Der zeitsinn nach versuchen. Tubingen, Germany: H. Laupp.

Vierordt, K. von (1870). Abhangigkeit der ausbildung des raumsinnes der haut von den beweglichkeit der korpert-

heile. Zeitschrift fur Biologie, 6, 5372.

The psychophysics of tactile perception and its peripheral physiological basis. In L. Kruger (Ed.), Pain and touch. San Diego, CA: Academic Press.

VIGILANCE, THEORIES OF. = sustained attention theories. In general, theories of vigilance refer to the systematic accounts of how observers maintain their focus of attention (i.e., the selective aspects of perception that function to help an organism focus on certain features of the environment to the exclusion of other features) and remain alert to stimuli over prolonged periods of time [i.e., sustained attention; cf., the law of prior entry - the principle that if a participant is attending to one of two possible stimuli and, if they occur simultaneously, the one to which he/she is attending tends to be perceived as having occurred before the other; in social/personality psychology, this is called the prior entry effect where the first impression(s) one has of another person tend to be the dominate one(s) and are not easily changed by further acquaintance; cf., also, laws of attention (Woodworth, 1921): selection - of two or more inconsistent responses to the same situation, only one is made at the same time; advantage - one of the alternative responses has an initial advantage over the others due to such factors as intensity and change in the stimulus, or to habits of reaction; shifting - the response that has the initial advantage loses its advantage shortly and an alternative response is made, provided the situation remains the same (cf., the law of shifting, proposed by the American psychologist Edward Lee Thorndike, which states that it is relatively easy to elicit a response that an organism is capable of performing in any situation - and to which it is sensitive - and, thereby, form an association between the response and the features of that situation); tendency - a predisposition when aroused to activity facilitates responses that are in its line and inhibits others; and combination - a single response may be made to two or more stimuli, and two or more stimuli may arouse a single joint response]. The various specific theories and models of vigilance attempt to deal with certain common questions in an observer's behavior during a vigilance task: How is background information stored? How are decisions made during observation? and How do neural attention units function? A sampling of the vigilance theories and some of their major tenets are: expectancy theory - observers act as "temporal averaging instruments" who form expectancies as to the approximate time course of critical signal appearances on the basis of samples of signal input; readiness to detect a signal is assumed to be positively related to level of expectancy; elicited observing rate hypothesis - the observer constantly makes sequential decisions about whether or not to emit observing responses toward the display that is monitored; detection failures occur when the participant does not emit the observing responses due to fatigue or low motivation or does so in an imperfect fashion; signal detection theory - the decrement function typically found in a vigilance task reflects a shift to a more conservative response criterion and decision process, rather than a decline in alertness or perceptual sensitivity to signals; activation/arousal theory - instead of a "cognitive" appraisal of vigilance, this approach emphasizes a neurophysiological explanation whereby sensory input has two general functions: to convey information about the environment and to "tone up" the brain with a background of diffuse activity that helps cortical transmission via increased alertness; this orientation suggests that the monotonous aspects of vigilance tasks reduce the level of nonspecific activity that is necessary to maintain continued alertness and, consequently, lead to a decline in the efficiency of signal detection; and habituation theory -habituation is a lessening of neural responsiveness due to repeated stimulation and is an "active process of inhibition;" this approach argues that the degree of neural habituation in a given task is directly related to the frequency of stimulus presentation so that with the development of habituation the observer's ability to discriminate critical signals is degraded, attention to the task becomes increasingly more difficult, and performance declines over a period of time; this theory holds that ha-bituation accumulates more rapidly at fast, than at slow, rates and results in a decline in performance at fast stimulus/event rates. The current status of vigilance theories is that each model focuses on a somewhat different aspect of the sustained attention situation, even though many theories can account for similar data. To date, the task remains of synthesizing the various theoretical positions of vigilance into a unified framework where stronger "lawful" cause-effect statements may be provided. See also ACTIVATION/AROUSAL THEORY; ATTENTION, LAWS/PRINCIPLES OF; ELICITED OBSERVING RATE HYPOTHESIS; HABITUATION, PRINCIPLE/ LAW OF; IMPRESSION FORMATION, THEORIES OF; REINFORCEMENT, THORNDIKE'S THEORY OF; SIGNAL DETECTION THEORY. REFERENCES

Woodworth, R. S. (1921). Psychology: A study of mental life. New York: Holt.

Deese, J. (1955). Some problems in the theory of vigilance. Psychological Review, 62, 359-368. Baker, C. (1963). Further toward a theory of vigilance. In D. Buckner & J. McGrath (Eds.), Vigilance: A symposium. New York: McGraw-Hill. Davies, D., & Tune, G. (1969). Human vigilance performance. New York: American Elsevier. Mackworth, J. (1969). Vigilance and habitua-

tion. Baltimore: Penguin Books. Stroh, C. (1971). Vigilance: The problem of sustained attention. New York: Per-gamon.

Mackie, R. (Ed.) (1977). Vigilance: Theory, operational performance, and physiological correlates. New York: Plenum.

Parasuraman, R., & Davies, D. (1989). Varieties of attention. Orlando, FL: Academic Press.

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