Phenomenon 11. The time for a keystroke is dependent on the specific context in which the character appears, especially for the topography of the keyboard (called the context phenomenon). The specific context here refers to the character ahead of and behind the target character. The context phenomenon is a combination of the alternate-hand advantage (phenomenon 7),the digram-frequency effect (phenomenon 8), the word-initiation effect (phenomenon 10), and, more specifically, the effect of topography of the keyboard in interacting with prior and subsequent keystrokes. For example, in typing the key sequence “r-e”, the close proximity of the two keys “r” and “e” in the same row on a standard QWERTY keyboard allows the middle finger on the left hand to move toward the target “e” while the index finger on the left hand is typing character “r”, which may save half of the movement

11. The time needed to produce a keystroke is dependent on the specific context in which the character appears. Basically this statement means that the interkey interval for a given character is not constant, but varies systematically as a function of thecharacters that precede it, and possibly those that follow it. Specific examples have been provided by Salthouse (1984b). Shaffer (1973. 1978), and Terzuolo and Viviani (1980).

This context phenomenon can be at least partially explained by means of the same mechanisms discussed earlier in connection with the alternate-hand advantage, the digram-frequency effect, and the word-initiation effect. That is, the time for a specific character will vary in different contexts because the character: (a) is sometimes preceded by a keystroke on the alternate hand and sometimes by a keystroke on the same hand, (b) is sometimes preceded by a letter that produces a high-frequency digram and sometimes preceded by one that produces a low-frequency digram, and � is sometimes the first character in a word and other times is in an interior or terminal position within the word. Although distinctive latency profiles for particular words have sometimes been interpreted as evidence for word-length motor programs (e.g.. Harding, 1933; Terzuolo & Viviani. 1980), Centner (1982, 1983b), Rumelhart and Norman (1982), and Shaffer (1973, 1978) have maintained that these profiles can be explained on the basis of local context effects primarily involving the structure of the hand and topography of the keyboard interacting with prior and subsequent keystrokes.

Of greater theoretical interest than the mere existence of the context effect is the length of the keystroke sequence over which such an influence is found to operate. Because these context effects can be presumed to originate primarily in the translation and execution operations, they can be interpreted as a reflection of the amount of advance preparation carried out for forthcoming keystrokes. That is, if there is an effect of context « characters in advance of a given character, then at least n + I characters (the current one and the preceding « characters) must be simultaneously available for processing in the translation and/or execution mechanisms. The maximum sequence at which contextual effects are observed thus provides an estimate of the buffer size of either the translation or execution processing operations.

The range of context effects is also interesting from the perspective of models proposing that typing proceeds via the retrieval and execution of motor programs for familiar letter sequences such as words (e.g., Leonard & Newman, 1965; Terzuolo & Viviani, 1980). The motor-program view maintains that the spatiotemporal parameters of the finger movements required for a specific character sequence are stored in memory as an integrated unit rather than being generated on-line during execution. However, the sequence length over which context effects are evident is still informative about the maximum size of the relevant units, which in this ease would be motor programs.

Several studies have indicated that the maximum length over which context effects are evident in skilled typists is only two to three characters. Shaffer (1978) reported that the interkey interval for a given character was different when the character two keystrokes before the character was varied and the intervening characters were constant, suggesting that there was a context effect extending over at least three characters. However, his data were based on a single highly skilled typist and therefore the generality not this finding was unclear. Gentner (1982. 1983b) considered greater number of typists and more alternative contexts. He reported that the variability of interkey intervals appeared to decrease as the amount of prior context was increased from zero to two characters, implying that the context effect may extend to three keystrokes. Very similar results were obtained by Salthouse (1985), in which typists ranging in skill from 18 to 113 net words per minute were found to be sensitive to prior context only up to an average of 1.76 characters in advance of the keystroke.


*Трансляция - имеется ввиду преобразованием мыслей соответствующие движения в двигательном центре.

Вы таки открыли спойлер, всё прочитали и даже что-то поняли? Я думаю, вы можете записать себя в красную книгу :), таких явно можно пересчитывать по пальцам.

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High- and low-frequency digrams are therefore postulated to be different in the integration and coordination of the finger movements for the two keystokes in the letter pair. Higher frequency pairs are expected to have a smooth transition with the preparation for the next keysiroke occurring during, and possibly even before, the execution of the present keystroke. In contrast, the keystrokes in low-frequency pairs are expected to be relatively independent of one another, with little or no adjustment of thefingers for the second keystroke during the preparation and execution of the first keystroke. At least part of this smoother and quicker transition between keystrokes may be attributable to a shifl toward movement specifications expressed relative to the current finger positions rather than in terms of the home-row positions. That is, with experience the typists may be able to make direct movements from one key to another without a return to the home-row positions, such as moving from r to t without first pausing above f. Videotape analyses of novice and expert typists would allow an examination of this speculation, but the relevant data have apparently not yet been collected.

Кстати, тоже интересный вопрос - как это дети уже класса со второго пишут с наклоном без линеек? Как это они угол меряют? Неужели это пальцевая интуиция?!

Про жесткозонную голь убило :D есть, значит, технологически богатый набор профи, а есть убогий жесткозонный набор суперменов и кибергонщиков))))