Order of report and order of scanning in tachistoscopic recognition.

Presented horizontal rows of 8 letters across fixation to 6 university students. An instruction cue told Ss to report the letters either in a left-to-right or in a right-to-left sequence. There were 5 different temporal intervals between test stimulus and instruction cue and an ad lib condition, where the instruction cue was triggered by the Ss. With increasing interstimulus interval, the serial position curve for right-to-left report showed a significant transition from an initial superiority for letters to the right of fixation to a superiority for letters to the left of fixation. It is concluded that the asymmetry of the tachistoscopic serial position curve is due to the order of scanning the fading contents of a visual information store. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Locus of presentation and the selective masking effect.

Obtained forward and backward masking functions for 4 adult Ss in a nonmetacontrast letter recognition paradigm for letters presented either foveally or 1.75. in the periphery with a patterned mask. Both forward and backward masking were greater for peripherally presented stimuli. Forward masking showed a greater sensitivity to locus of presentation than backward masking. Results are considered in relation to the "ends-first" processing strategy explanation of the selective masking effect proposed by P. M. Merikle, et al. (French summary) (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detecting targets in letter and non-letter arrays.

Three experiments with 48 right-handed undergraduates examined the difference between the processing of letter and nonletter arrays using visual search. Results show that (1) letters were processed differently from other shapes; specifically, detection latencies were relatively short for the ends of letter arrays and increased left to right yielding a sloping M-shaped function, whereas the function for nonletter arrays was U-shaped; (2) this result was not restricted to any one nonletter character set, nor is visual familiarity or nameability crucial; and (3) digits produced results comparable to letters. Mechanisms common to word and number processing are advanced to account for this latter finding. The basic letter–shape contrast shows that the letter position function is constrained by processing strategy, not by structural limitations. (French abstract) (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simon-Type Effects: Chronometric Evidence for Keypress Schemata in Typewriting.

In 4 experiments, chronometric evidence for keypress schemata in typing was sought by presenting stimuli to be typed in positions that were displaced from a central fixation point. Reaction times were shorter when stimulus positions corresponded to keyboard locations of the letters to be typed, suggesting that position was an important part of the internal representation of the response. Experiment 1 presented single letters left and right of fixation. Experiment 2 presented single letters above and below fixation. Experiment 3 presented words left and right of fixation and found evidence of parallel activation of keypress schemata. Experiment 4 found no effect of the eccentricity of the keyboard locations and responding fingers, suggesting that response-location codes are categorical, not metric. The results are consistent with D. E. Rumelhart and D. A. Norman's (1982) theory of typewriting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Crowding affects letters and symbols differently.

Five experiments examined crowding effects with letter and symbol stimuli. Experiments 1 through 3 compared 2-alternative forced-choice (2AFC) identification accuracy for isolated targets presented left and right of fixation with targets flanked either by 2 other items of the same category or a single item situated to the right or left of targets. Interference from flankers (crowding) was significantly stronger for symbols than letters. Single flankers generated performance similar to the isolated targets when the stimuli were letters but closer to the 2-flanker condition when the stimuli were symbols. Experiment 4 confirmed this pattern using a partial-report bar probe procedure. Experiment 5 showed that another measure of crowding, critical spacing, was greater for symbols than for letters. The results support the hypothesis that letter-string processing involves a specialized system developed to limit the spatial extent of crowding for letters in words. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Choice reaction-time study assessing the verbal behavior of the minor hemisphere in normal adult humans.

Conducted 2 choice RT experiments in which a total of 12 right-handed college students scanned a memory set of 1 or 6 letters for the presence of a test letter. The memory set was presented binaurally and the test letter visually to either the right or left visual field. S indicated with his left hand whether or not the test letter was contained in the memory set. Results show the RT was shorter for the left visual field test letter when the set contained only 1 letter and for the right visual field test letter when the set contained 6 letters. The possibility that Ss matched the set and test letters visually when the set contained only 1 letter and verbally when the set contained 6 letters is discussed. Results suggest that the minor hemisphere displays little, if any, verbal abilities. (31 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual hemifield differences in the perception of letters and contour orientation.

In Exp. I, 10 students were required to recognize capital English letters presented 3– to the left or to the right of a fixation point. In Exp. II, 8 Ss were required to discriminate the orientation of a line presented in either the left or the right visual hemifield. In both experiments Ss displayed a significant right visual hemifield superiority, and a marked positive correlation was observed in the hemifield differences between the 2 recognition tasks. Results suggest that for certain classes of stimuli visual laterality differences may be subserved by a selective contour-tuning mechanism. (French summary) (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some temporal characteristics of processing during reading.

14 college students read passages displayed on a CRT as their eye movements were being monitored. During occasional fixations, all letters to the left of the directly fixated letter or all letters more than 4 to the right of the fixated letter were replaced by other letters. This replacement occurred either for only the 1st 100 msec of the fixation or only after the 1st 100 msec of the fixation. Eye movement data indicate that the eyes could respond to change in the visual stimulus within less than 100 msec and to orthographic irregularity in the test within less than 160 msec. No evidence was found for a left-to-right attentional scan during a fixation. Results are interpreted within the framework of a chronology of processing events occurring during a fixation in reading. Eye movement patterns and the determination of fixation durations are discussed. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transposed-letter effects in reading: Evidence from eye movements and parafoveal preview.

Three eye movement experiments were conducted to examine the role of letter identity and letter position during reading. Before fixating on a target word within each sentence, readers were provided with a parafoveal preview that differed in the amount of useful letter identity and letter position information it provided. In Experiments 1 and 2, previews fell into 1 of 5 conditions: (a) identical to the target word, (b) a transposition of 2 internal letters, (c) a substitution of 2 internal letters, (d) a transposition of the 2 final letters, or (e) a substitution of the 2 final letters. In Experiment 3, the authors used a further set of conditions to explore the importance of external letter positions. The findings extend previous work and demonstrate that transposed-letter effects exist in silent reading. These experiments also indicate that letter identity information can be extracted from the parafovea outside of absolute letter position from the first 5 letters of the word to the right of fixation. Finally, the results support the notion that exterior letters play important roles in visual word recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A note of familiarity and scanning with tachistoscopic recognition.

D. J. Mewhort et al (see record 1969-12246-001) have argued that familiar sequences of letters are reported more accurately than random sequences, in a tachistoscopic task, because the arrays are processed more rapidly by a serial, left-to-right encoding operation. This scanning hypothesis predicts an interaction between familiarity and position, if scanning is interrupted, and a 3-way interaction with familiarity, position, and time, if processing time is manipulated. As predicted by the hypothesis, these interactions were present with free-recall of closely spaced sequences (Exp I, 14 Ss) but were absent for the results with widely spaced sequences (Exp II, 12 Ss). (French summary) (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of order of approximation to English and letter array length in the development of visual laterality.

24 7 yr 10 mo–10 yr 8 mo-old children identified tachistoscopically presented arrays varying in length and degree of orthographic constraint. A right hemifield superiority was found for all Ss and conditions. Longer arrays resulted in asymmetric serial position curves with most accurate identification of the 1st letters on the right. The influence of orthographic structure was evident at all age levels and in both hemifields. Results suggest that although a left to right postexposural scanning process may contribute to general hemifield asymmetries, their change with age is more likely associated with other factors. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The roles of stimulus-response compatibility and mental rotation in mirror-image and left-right decisions.

Examined the relative roles of mental rotation and stimulus-response (SR) compatibility in mirror-image and left-right decisions. 15 Ss, aged 19–43 yrs, were shown rotated letters and asked to indicate whether the letters were normal or backward (mirror-image task). Ss were then asked whether a dot would be located to the left or right of each letter if the letter was upright (viewer-centered left-right task) or if the letter was both upright and normal (letter-centered left-right task). The functions relating reaction time (RT) to angular orientation were parallel across the 3 tasks, suggesting that SR compatibility played no role, and that the Ss mentally rotated the letters to the upright in each case. A marked increase in RT to backward letters in the letter-centered task suggested a 2nd rotation in depth to restore the letters to normal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reading ability and single-letter orthographic redundancy.

Two experiments investigated the role of one form of intraword orthographic redundancy: the characteristic asymmetric spatial distributions of letters of the alphabet across serial positions within words. In Exp I, 81 college students demonstrated recognition knowledge of these distributions when given only the letter name, word length, and serial position information with no other context. Ss were correct more often for those letters which are least variable across serial positions. In Exp II, 28 5th graders who were skilled readers demonstrated a sensitivity to letter positional distributions similar to that of the adults; 20 poor readers did not. However, performance was equivalent for both good and poor readers on a subset of letters relatively unpredictable with respect to serial position. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unexceptional spatial memory in an exceptional memorist.

Rajan Mahadevan evidences an exceptional memory for arrays of digits. The authors tested whether Rajan's spatial memory was likewise exceptional. Eight control Ss and Rajan were instructed to remember the position and orientation of 48 images of common objects shown either to the left or the right of fixation and facing either left or right. Rajan's accuracy for judging whether the position and orientation of these pictures had changed when they were shown in a different sequence was lower than that of control Ss for both judgments. Rajan's exceptional memory capacity apparently does not extend to spatial relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eye movements when reading transposed text: The importance of word-beginning letters.

Participants' eye movements were recorded as they read sentences with words containing transposed adjacent letters. Transpositions were either external (e.g., problme, rpoblem) or internal (e.g., porblem, probelm) and at either the beginning (e.g., rpoblem, porblem) or end (e.g., problme, probelm) of words. The results showed disruption for words with transposed letters compared to the normal baseline condition, and the greatest disruption was observed for word-initial transpositions. In Experiment 1, transpositions within low frequency words led to longer reading times than when letters were transposed within high frequency words. Experiment 2 demonstrated that the position of word-initial letters is most critical even when parafoveal preview of words to the right of fixation is unavailable. The findings have important implications for the roles of different letter positions in word recognition and the effects of parafoveal preview on word recognition processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A further test of the scanning hypothesis in a tachistoscopic recognition.

2 groups of 10 undergraduate Ss participated in an experiment where a horizontal row of 8 letters was tachistoscopically presented across fixation. One group was required to report the letters in alphabetic order; the other received no specific instruction regarding order of report. The alphabetic order of report instruction effectively eliminated any systematic relationship between position in the report sequence and position in the stimulus. Free order of report was usually in a left-to-right sequence with respect to stimulus position. In spite of the difference between order of report, no difference in the left-field superiority for the 2 groups was found. It is concluded that left-field superiority in tachistoscopic recognition cannot be explained on the basis of left-to-right responding. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Repetition blindness, forward and backward.

In these experiments, 2 letters were presented sequentially to the left and right of fixation, followed by pattern masks. Report was cued by spatial location (Experiments 1a, 1b, 2, 4, and 5) or temporal position (Experiments 3, 4, and 5). In all experiments, 2 identical letters on a trial resulted in reduced accuracy of report (repetition blindness; RB) for both the 1st and 2nd presented letters. This decrement was greater for the 2nd letter if subjects expected temporal cues, but tended to be greater for the Ist letter if they expected spatial cues. Analyses of errors and responses on catch trials indicated no bias against report of repetitions, and the repetition decrement did not interact with output order. The data are inconsistent with both type-refractoriness and memory-retrieval accounts of RB. A modified version of N. G. Kanwisher's (1987) token-individuation theory is proposed to account for the results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Word superiority over isolated letters: The neglected role of flanking mask contours.

When stimuli are presented in pattern-postmasked displays, performance is better for words than for isolated letters. Contemporary accounts of this word advantage emphasize the role played by mask contours that overlay the positions of letters in each stimulus; however, the precise effect of these overlying mask contours has never been empirically determined. The role of overlying and flanking (falling to the left and right of each word and isolated letter) mask contours in the word advantage over isolated letters was examined. A word advantage was obtained only when more flanking mask contours were shown with isolated letters than with words; when masks covered only the positions of letters in each stimulus, and thus no flanking mask contours were presented, the word advantage was removed or reversed. Implications for contemporary accounts of the word advantage over isolated letters are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence for sequential processing in visual word recognition.

The orthographic uniqueness point (OUP) of a word is introduced as the position of the 1st letter, reading from left to right, that distinguishes a word from all other printed words. In 3 experiments, observers named words that had early versus late OUPs. With unlimited viewing time, early-OUP words were named faster than late-OUP words. The effect disappeared in a delayed-naming task; hence, it was not associated with response production. The effect remained when exposure duration was reduced to limit eye movements. Results indicate that observers process the letters of a word in left-to-right order, contrary to strictly parallel accounts of word identification. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of stimulus arrangement on hemispheric differences and interhemispheric interaction for processing letter trigrams.

Observers identified consonant-vowel-consonant (CVC) nonsense syllables with the letters arranged horizontally. In each of 2 experiments, there were fewer errors when stimuli were presented to the right visual field (RVF) and left hemisphere (LH) than when stimuli were presented to the left visual field (LVF) and right hemisphere (RH), and the extent to which the number of last-letter errors exceeded the number of first-letter errors was greater on LVF/RH than on RVF/LH trials. When the same stimulus was presented simultaneously to both visual fields (Experiment 2), the qualitative error pattern was very similar to the pattern obtained on LVF/RH trials. These effects replicate results obtained in earlier CVC identification experiments with letters arranged vertically. However. when a single stimulus was presented in the center of the visual field (Experiment 1), so that the first letter of the CVC projected to the LVF/RH and the last letter projected to the RVF/LH, the error pattern was a mixture of the LVF/RH and RVF/LH patterns, as if each hemisphere took the lead for processing the letter it received directly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)