In a visual-detection experiment. a display of severalletters was presented. and S was to report the presence or absence of a given target letter. Results clearly are incompatible with a selfterminating visual-scanning process as hypothesized by Sternberg (1967). Two models are considered. a serial exhaustive scanning process and a parallel exhaustive process, but findings from the present study do not provide a basis for differentiating between them.In several experiments, Taylor (1964, 1966) have studied the visual-detection process for the case in which S searches for one of a predesignated pair of letters (signal or critical elements) imbedded within a tachistoscopically presented display of noise letters. A forced-choice design was used with S responding that he saw one or the other of the critical elements on every trial, even if the detection was uncertain. The models proposed to account for the results assume S samples a proportion of the letters present on each trial, and then serially scans through them to determine which target letter was included in the display. If the target letter is among the letters sampled, S makes the appropriate response after processing the critical element. If, however, the target letter is not included among the elements sampled on that trial, S guesses one of the two alternatives. These models accurately predict an increase in error rate with an increase in the number of noise elements in the display, but a deeper analysis of the scanning process is difficult to achieve using their data primarily because of the somewhat random placement of letters within the display and the lack of latency measures.By measuring response latencies in a similar experiment, Estes and Wessel (1966) were able to demonstrate that error latencies remain essentially constant across display sizes, indicating that S continues processing elements in searching for a match with one of the target letters until some temporal criterion is reached (perhaps the point at which the registered image of the display has decayed beyond usefulness in extracting information), at which point S guesses. The data also indicated that the search process might terminate with a correct response as soon as the target letter is processed. Estes and Wessel based both of these latter inferences upon latency data that had been corrected for guessing, admittedly leaving definite conclusions about the nature of the scanning process for further research.Using a different paradigm, Sternberg (1966) has presented evidence for serial and exhaustive scanning of elements stored in memory. On each trial S was given a list of one to six digits to remember. A single test digit was then presented, and S responded by pulling an appropriate lever to indicate whether or not the test digit matched any of those in memory. In this experiment there were virtually no errors, allowing latency scores to be used without correction. Plotting latency against memory set size, Sternberg was able to draw two important conclusions: (a) The data could be...

Is there a difference in the kind of attention elicited by an abrupt-onset peripheral cue and that elicited by an instruction (e.g., a central arrow cue) to move attention to a peripherallocation? In Experiment 1, we found that peripheral cues are no more effective in orienting attention than are central cues. No evidence was found for separable attentional systems consisting of a volitional response to central cues and an automatic response triggered only by peripheral cues. Rather, an identical or similar attentional process seems to be activated by either type of cue, although perhaps in different ways. Peripheral cues seem to have an automatic component, however, in that once attention is engaged by a peripheral cue, it cannot easily be disengaged for refocus elsewhere. In Experiment 2, after several sessions of practice, subjects were able to circumvent automatic attentional capture by an abrupt-onset peripheral cue and to volitionally redirect the focus of attention. Thus, attentional capture by abrupt-onset stimuli is not strongly automatic.

No abstract

No abstract

Just, Carpenter, and Woolley propose that measures of single-word processing times, such as gaze durations during normal reading or durations of reader-controlled exposures, can be used both for developing theories of comprehension and for determining the course of new reading technologies. We argue that better understanding of comprehension processes does not necessarily follow from observed correlations between text variables and eye-fixation parameters. Further, recent rapid serial visual presentation (RSVP) research suggests that eye fixation data obtained from studies of normal reading might have little practical value in optimizing the readability of RSVP displays and other means of text presentation.