The importance of being first: A tachistoscopic study of the contribution of each letter to the recognition of four-letter words

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The early versus late selection issue in attention models was examined by means of a new methodology. Through cues or precues, attention was directed to one location of a multistimulus visual display and, while attention was so engaged, the identity of a stimulus located at a different position in the display was changed. By varying the time after display onset before the stimulus was changed, we controlled the preview time that the original stimulus was represented on the retina. Then, using a marker cue, we directed the subject's attention to the location of the changed stimulus. The subject's response was a timed discrimination between two possible target letters. The data of main interest was the effect of preview time upon the subject's latency in identifying the new target that appeared in the changed location. We found that the preview time of the original stimulus, before RT was affected to the new target, depended upon whether the original stimulus was a neutral (noise) letter or whether it was the alternative target. When the original stimulus was a noise letter, RTs to the new target were just as fast as those obtained in the control condition in which the target was present throughout the preview interval and did not change its identity. Significant effects upon RT were obtained at preview times of 83 msec when the original stimulus was one of the targets that changed to the alternative target. Preview times also varied as a function of precuing. Preview times were correspondingly shortened when the first cue occurred 50 msec before display onset, thus providing an extra 50 msec for attention to be directed to the first display location. The results were interpreted in terms of two separate information-processing systems in the human: an automatic system and an attentional system. Even though a stimulus may have been automatically processed, when the attention system is directed to that stimulus, processing starts at the beginning again.Pashler (1984) has presented a series of experiments that call into serious question a basic assumption of lateselection theories of attention, namely, that stimuli are parallel-processed and identified before attentional processing is engaged. In these experiments, Pashler used a modification of the iconic memory paradigm of Averbach and Coriell (1961). In the paradigm, an overload of visual information is presented for a brief duration and then, at various intervals after the display has been terminated, a bar or cue designates a location in the visual field. The subject is asked to report the stimulus that had occupied that location in the display. The now classic result is that accuracy of report decreases rapidly as the cue is delayed with performance, becoming asymptotic at around 300 msec.In his first experiment, Pashler modified the Averbach and Coriell procedure in several ways. He used displays of eight letters presented in two rows of four characters each. Three probe conditions were used. In the early-probe condition, the probe preceded the display by 200...

Section: Discussionmentioning

confidence: 97%

How much processing do nonattended stimuli receive? Apparently very little, but...

Eriksen

Webb

Fournier

1990

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“…Oleron (1970), using words constructed from an artificial alphabet, found a similar ordering by position for the effectiveness of letters with tails (analogous to p or b, for example) as cues to word recognition. Several more studies have reported the importance of initial letters to successful word processing without finding evidence for consistent differential contributions from subsequent letter positions (e.g., Eriksen & Eriksen, 1974; Goldsheider & Muller as reported in Huey, 1908;Melville, 1957;Singer, Lappin, & Moore, 1975). In general, then, it seems that initial letters are always critical to word processing, while terminal letters contribute more or less critical information depending on the nature of the task demands made upon the perceiver.…”

Section: Discussionmentioning

confidence: 99%

Target position and practice in the identification of letters in varying contexts: A word superiority effect

Carr

Lehmkuhle

Kottas

et al. 1976

A forced-choice detection paradigm controlling for postperceptual inference was used to investigate letter identification in three-position displays. Letters from a predesignated set of four targets appeared singly, in strings of noise characters, in unpronounceable nonsense strings, and in words. Subjects knew which context would occur, but did not know which of the three display positions would contain the target. Correct detection data were collected at constant exposure duration over five testing sessions. Overall identification accuracy was higher in words than in all other contexts, the first word superiority effect to be found with targets specified in advance since Reicher's (l969). This effect remained constant over sessions. An interaction between context type and target position showed enhanced accuracy for initial and terminal letters in words, but depressed accuracy at initial and terminal positions in other contexts. This was interpreted to mean that prior knowledge of context is used to alter the dynamics of perceptual analysis.In 1969, Reicher reported a word superiority effect, in which letters were more accurately identified when presented in words than when presented alone or in nonsense strings. Since then, much research has been directed toward defining the experimental conditions under which a word superiority effect can be found, and inferring from those conditions the locus of the effect in the course of information processing (e.g., Bjork

“…In the reaction time paradigm, performance is typically better when the target is in the beginning of a letter string (e.g., B. A. Eriksen & C. W. Eriksen, 1974;Krueger, 1975), whereas in the typical WSE experiment, performance is typically better when the target is in the middle of a letter string (see, e.g., Rumelhart & McClelland, 1982). Thus, it is not certain that a WSE would be obtained with accuracy as the dependent variable without a brief exposure.…”

mentioning

confidence: 99%

The word-superiority effect does not require a T-scope

Prinzmetal

1992

Six experiments examined the possibility of obtaining a word-superiority effect (WSE) without the use of brief stimulus exposures or a poststimulus mask. In each experiment, subjects were presented a stimulus string and two alternative strings that differed by a single letter (Reicher, 1969). The alternatives and stimulus remained in view until subjects responded, and subjects were under no pressure to respond quickly. In Experiments 1-3, the stimuli were presented in very small type so that they were difficult to see. Subjects were significantly more accurate with words than with nonwords, letters embedded among digits, or letters embedded among number signs (#s). In Experiments 4 and 5, the stimuli were embedded in a simultaneously present pattern mask. Subjects were significantly more accurate with words than with single letters by themselves. In the final experiment, the stimuli were presented in a mask with specific spatial frequency characteristics, and performance was significantly better with words than with nonwords. The WSE is a more general phenomenon than previously supposed; it is not limited to a tachistoscopic exposure.Experiments in which visual stimuli are briefly presented in order to limit perfonnance are ubiquitous in experimental psychology. Instruments used to briefly present stimuli have included the electric spark generator, the gravity chronometer (Cattell, 1885), an oil lantern behind a photographic shutter (pillsbury, 1897), the tachistoscope, the point plotter, and the raster display of the familiar personal computer. Generically. these devices are known as T-scopes. Volumes of research have been based on the use of T-scopes, in one form or another.Despite the preponderance of this research, a few skeptics have questioned whether the results of T-scope experiments are informative about perception in more naturalistic settings. For example, Dodge (1907) likened studying vision with a brief exposure to perception in a thunderstorm. He contended not only that the results would fail to generalize to more naturalistic situations, but that the use of too brief an exposure would result in "making the conclusions not merely valueless but false" (p. 32). Katz (1925Katz ( /1989 complained that the frequent use of the T-scope led to a "tachistoscopic mentality." A more modem iconoclast, who was showing visitors his laboratory, is reported to have pointed to the room housing the tachistoscope and to have commented, "the devil lives there." It is true that we are rarely called upon to read briefly presented stimuli, except perhaps in a thunderstorm or in a discotheque with stroboscopic lighting.Nevertheless, research with brief exposures has led to many important findings, and so it may be rash to deni- grate this research. One of the best known of these findings, which is the subject of this paper, is Reicher's (1969) discovery of the word-superiority effect (WSE). Reicher briefly presented words, nonwords, or single-letter stimuli, followed by a visual noise mask. Subjects had to determine which...