The use of information below fixation in reading and in visual search.

Two experiments examined whether or not readers obtain useful information from below the currently fixated line. In Exp 1, 15 adults read passages of text, and the availability of visual information below the line fixated was manipulated using a variant of the moving window technique. Reading was no slower when there was no letter information below the fixated line than when there was full information below the fixated line. However, a condition that made the strings of letters below the fixated line less wordlike caused reading to be slowed down by about 6%. In Exp 2, 15 adults searched for a target word through passages of text. There was no clear evidence that the availability of information below the line made search more efficient. It appears that in reading, little visual information is extracted below the line of text fixated. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of eye movements in the missing-letter effect revisited with the rapid serial visual presentation procedure.

When participants read a text while searching for a target letter, they are more likely to miss the target letter embedded in frequent function words than in less frequent content words. This effect is usually observed with a text displayed normally, for which it has been found that frequent function words are fixated for a smaller amount of time than less frequent content words. However, similar pattern of omissions have been observed with a rapid serial visual presentation procedure in which words appear one at a time. These parallel results would demonstrate that fixation duration per se is not the proximal cause of the missing-letter effect only if eye movements are not made during the rapid serial visual presentation procedure. Therefore, the authors performed eye monitoring during the rapid serial visual presentation procedure. Results revealed that, with a rapid serial visual presentation procedure, participants fixated function and content words for almost the entire presentation duration. It is concluded that eye movements are not the proximal cause of the missing-letter effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eye-hand span and coding of text during copytyping.

Examined concurrent oculomotor and manual activities during copytyping to determine whether (1) typists keep the eyes 1-sec ahead of the executed keypress, (2) control of eye–hand (E–H) coordination follows the lexical representation of to-be-typed text, and (3) typists seek visual information beyond the boundaries of the fixated word. To-be-typed text contained high- and low-frequency target words that were either short or long. Two viewing conditions were used revealing either the directly fixated word only or the fixated word plus the next word in the text. The results showed no support for the 1-sec E–H lag hypothesis. The E–H span was also not affected by the visibility of text but was a function of word frequency, suggesting that E–H coordination follows the lexical representation of text. Effects of window size indicated that typists seek visual information beyond the boundaries of the fixated word. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of parafoveal processing on the missing-letter effect.

According to the parafoveal-processing hypothesis, letters are more often missed in function words than in content words because the former are more likely to be identified in the parafovea, where letter processing is not available. Contrary to previous demonstrations, more omissions occurred in function words than in content words when parafoveal processing was not available because words were displayed in column format, text was read through a 5-letter window, or words were presented 1 at a time on a computer screen. In all experiments, impeding parafoveal processing decreased omission rates for function but not for content words. In the last experiment, direct monitoring of eye movements revealed that, for both fixated and skipped words, letters in function words are missed more often than content words. These results are best interpreted within a model including the structural precedence hypothesis and stressing the importance of visual factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of short-term memory codes on visual image processing: Evidence from image transformation tasks.

Three experiments showed that phonological recoding of visual stimuli in short-term memory affects coding in long-term memory (LTM) and therefore performance on tasks involving generation and manipulation of visual images of the stimuli. An image transformation task was devised. It consists of mentally subtracting a part of an image to discover in the remainder another object. In Exp 1, Ss were required to learn a set of easily nameable visual stimuli and then perform the subtraction task on images retrieved from LTM. Performance was significantly better when initial learning was accompanied by articulatory suppression (AS). Exp 2 confirmed that AS had no effect when the task was performed on an image of a just-presented stimulus. In Exp 3, the nameability of the stimuli was manipulated. The results replicated the effect of AS for items that were easy to name but showed no effect of AS for stimuli that were difficult to name. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orthographic Structure Versus Morphological Structure: Principles of Lexical Organization in a Given Language.

Most models of visual word recognition in alphabetic orthographies assume that words are lexically organized according to orthographic similarity. Support for this is provided by form-priming experiments that demonstrate robust facilitation when primes and targets share similar sequences of letters. The authors examined form-orthographic priming effects in Hebrew, Arabic, and English. Hebrew and Arabic have an alphabetic writing system but a Semitic morphological structure. Hebrew morphemic units are composed of noncontiguous phonemic (and letter) sequences in a given word. Results demonstrate that form-priming effects in Hebrew or Arabic are unreliable, whereas morphological priming effects with minimal letter overlap are robust. Hebrew bilingual subjects, by contrast, showed robust form-priming effects with English material, suggesting that Semitic words are lexically organized by morphological rather than orthographic principles. The authors conclude that morphology can constrain lexical organization even in alphabetic orthographies and that visual processing of words is first determined by morphological characteristics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

German Capitalization of Nouns and the Detection of Letters in Continuous Text.

The missing-letter effect refers to the phenomenon that letters are more difficult to detect in common function words (such as the) than in content words. Assuming that the missing-letter effect is diagnostic of the extraction of text structure, we exploited a special feature of German - the convention to capitalize the initial letter of nouns. Given the great flexibility of word order in German, it was proposed that this convention might help readers specify the structure of the sentence. Therefore orthographic variations that violate the capitalization rules should disrupt structure extraction and should result in a reduced missing-letter effect. The results indicated that: 1) capitalization of function words eliminated the missing-letter effect, but not at the beginning of a sentence; 2) A missing-letter effect occurred when the capitalization of the first letter was correct, but was followed by type-case alternation, and also when the size of the initial letters was relatively large for function words, but relatively small for content words. The results were discussed with respect to the possible contributions of visual familiarity, structural role, and processing time to the missing-letter effect, taking into account that a capitalized initial letter conveys significant information about the word class for German readers. Thus, the present results indicate that readers take advantage not only of function words but of any other information (here the capitalization of nouns) that helps to extract the structure of a sentence. (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)     

Priming and response selection processes in letter classification and identification tasks.

The processing of isolated visual letters was studied by means of a priming paradigm. In alphabetic (letter vs nonletter) classification, any letter prime reduced response times to letter targets. Additional facilitation occurred only with primes physically identical to the target. In letter naming, facilitation was seen with primes nominally identical to the target even when they were physically different. This result is not due to phonological priming because phonologically similar primes had no effect on naming times. Primes nominally different from the target but physically similar to it increased naming times. The classification task seems to be performed through the global monitoring of stored visual knowledge of letters. In contrast, the absolute identification of letters appears to rest on a signal-to-noise statistic derived from an abstract encoding of letter identities. Connectionist simulations provide support for these proposals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reevaluating encoding-capacity limitations as a cause of the attentional blink.

A number of researchers have emphasized the role of distractors intervening between successive targets as the primary determinant of the attentional blink (AB) phenomenon. They argued that the AB is abolished when 3 or more targets are displayed as temporally contiguous items in rapidly presented serial sequences. In 3 experiments, the authors embedded 1-, 2-, or 3-digit targets among letter distractors in rapidly presented visual sequences. Across the experiments, both the number of targets and the lag between them were manipulated, producing different proportion of trials in which 3 temporally contiguous targets were presented in the test session. Evidence of an AB affecting the targets that followed the first target in these sequences was found in each experiment when the probability of a given target report was conditionalized on a correct response to the preceding targets, thus reinforcing the notion that some form of capacity limitation in the encoding of targets plays a central role in the elicitation and modulation of the AB effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Image generation and processing of generated images in the cerebral hemispheres.

Recent computational models describing the contribution of the cerebral hemispheres to visual imagery have suggested an exclusive capacity of the left hemisphere to generate multipart images. A brief review of relevant findings indicates that the evidence presented in support of this suggestion is not entirely compelling; this prompted a reexamination of this issue in a lateral tachistoscopic study on normal adults. Sixteen subjects participated in two experiments in which they had to decide whether or not a lowercase letter contained a segment extending above or below the main body of the letter. This decision was made directly on lowercase letters in one experiment (perceptual task) and on their generated images in the other experiment (imagery task). The quality of the letters (clear or blurred) and the retinal eccentricity of stimulus presentation (small or large) were orthogonally manipulated. The perceptual task yielded no main effect of visual field but a significant interaction of visual field and letter quality. By contrast, the imagery task resulted in a left visual-field superiority but no interaction involving the visual fields—a departure from predictions based on current models of visual imagery. In addition, the pattern of results in the imagery task corresponded to that obtained with blurred letters in the perceptual task, suggesting limitations in spatial resolution of visual images. Implications of these results for models of cerebral lateralization and visual imagery are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Functional equivalence of spatial images from touch and vision: Evidence from spatial updating in blind and sighted individuals.

This research examined whether visual and haptic map learning yield functionally equivalent spatial images in working memory, as evidenced by similar encoding bias and updating performance. In 3 experiments, participants learned 4-point routes either by seeing or feeling the maps. At test, blindfolded participants made spatial judgments about the maps from imagined perspectives that were either aligned or misaligned with the maps as represented in working memory. Results from Experiments 1 and 2 revealed a highly similar pattern of latencies and errors between visual and haptic conditions. These findings extend the well-known alignment biases for visual map learning to haptic map learning, provide further evidence of haptic updating, and most important, show that learning from the 2 modalities yields very similar performance across all conditions. Experiment 3 found the same encoding biases and updating performance with blind individuals, demonstrating that functional equivalence cannot be due to visual recoding and is consistent with an amodal hypothesis of spatial images. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Letter localization, not discrimination, is constrained by attention

Shaw (1984; Shaw, Mulligan & Stone, 1983) measured the probability of detecting a target letter in displays containing different numbers of items. The set size effect was significantly larger than the effect predicted by unlimited-capacity models of visual processing, and Shaw concluded that attention constrains the discrimination of complex, but not simple, patterns. We re-examined the role of attention in letter discrimination by measuring the effect of set size on the contrast needed to identify a target embedded among distractors. The results of 5 experiments show that set size effects are small for letter discrimination, but large for letter localization. The findings suggest that the large set size effect reported by Shaw (1984) was a result of asking subjects to localize the target. In addition, the results are consistent with the hypothesis that limited processing capacity constrains the perceptual processes involved in letter localization, but not discrimination.     

Flexibility in scanning described images.

Two experiments investigated why past research has shown that described images lead to the typical increase in reaction time (RT) with increasing memory set size (m), but undescribed images do not. Experiment 1 used ms 6 through 8. A described image group showed a linear relation between m and RT up to a m of 6, and no increase in RT thereafter. A story group (which was asked to tell a brief story for words in a memory set) and a repetition group showed a linear relation between m and RT throughout the range of ms, whereas an image group showed no relation between m and RT. Experiment 2 essentially replicated the first experiment but manipulated memory strategy as a within subject variable. Similar results were found. The apparent change from "serial" to "parallel" processing by the described image groups in both studies reinforces the notion of flexibility in processing, particularly when multiple representations are formed or when multiple encoding strategies are used. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Familiarization effects for bilingual letter detection involving translation or exact text repetition.

In two experiments, English-Spanish bilinguals read passages, performing letter detection on some passages by circling target letters as they read. Detection passages were sometimes familiarized (primed) by prior reading of the same passage or a translation of it. Participants detected letters in English passages in Experiment 1 and in Spanish passages in Experiment 2. For both experiments, a missing letter effect occurred (depressed detection accuracy on frequent function words relative to less frequent content words). Familiarization promoted overall improvements in letter detection only for English passages, suggesting that reprocessing benefits depend on high language fluency. For Spanish passages, cognates engendered greater error rates than noncognates; the visual similarity of Spanish and English cognates apparently enabled faster identification of Spanish cognates in a way unaffected by familiarization of the whole text passage. Priming by familiarized text was significantly higher when the passages were in the same language than when they were in different languages, suggesting that the reprocessing benefits are at the word level instead of the semantic level. These results are consistent with the GO model of reading (Greenberg, Healy, Koriat, & Kreiner, 2004) but require an expanded consideration of attention redistribution processes in that model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vernier and letter acuities for low-pass filtered moving stimuli

Vernier and letter acuities are both susceptible to degradation by image motion. In a previous study, we showed that the worsening of Vernier acuity for stimuli moving up to 4 degrees/s is accounted for primarily by a shift of visual sensitivity to mechanisms of lower spatial frequency. The purposes of this study were to extend the previous results for Vernier acuity to higher stimulus contrast and velocities, and to determine if a shift in spatial scale can similarly explain the degradation of letter acuity for moving stimuli. We measured Vernier discrimination for a pair of vertical abutting thin lines and letter resolution for a four-orientation letter 'T' as a function of stimulus velocity ranging from 0 to 12 degrees/s. Stimuli were presented at 20 times the detection threshold, determined for each velocity. To determine the spatial-frequency mechanism that mediates each task at each velocity, we measured Vernier and letter acuities with low-pass filtered stimuli (cut-off spatial-frequency: 17.1-1.67 c/deg) and analyzed the data using an equivalent blur analysis. Our results show that the empirically determined, equivalent intrinsic blur associated with both tasks increases as a function of stimulus velocity, suggesting corresponding increases in the size of optimally responding mechanisms. This progressive increase in mechanism size can account for the worsening of Vernier and letter acuities with velocity. Vernier discrimination is found to be more susceptible to degradation by various stimulus parameters than letter resolution, suggesting that different mechanisms are involved in the two tasks. We conclude that the elevations in Vernier and letter acuities for moving stimuli are the consequence of a shift of visual sensitivity toward mechanisms of lower spatial frequencies.     

Mechanisms of imagery-perception interaction.

A number of different research findings have shown that mental imagery can affect the perceptual processing of stimuli. The present research was aimed at characterizing the representations and processes underlying imagery–perception interactions. In 4 experiments, Ss mentally projected images of letters into the visual field, and either detected or detected and localized point threshold stimuli that fell on or off the image. Stimuli falling on the image were detected more often than stimuli falling off the image, consistent with the hypothesis that the representations at the interface between imagery and perception have an array format. When the facilitation was analyzed in terms of signal detection theory, it was found to consist only of criterion lowering, and not of enhanced sensitivity. The local criterion-lowering effect of imaged letters was then compared with the effect of perceiving a letter and attending to a letter. Perceiving a letter had no discernible effect on stimulus detection, whereas attending to the letter caused the same local criterion lowering, without sensitivity changes, as imaging the letter. This is consistent with the claims of U. Neisser (1976) and others that imagery is an attentional state. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual search for natural grains in pigeons (Columba livia): Search images and selective attention.

The experiments reported here were designed to test the suggestion of many researchers that selective attention to visual features of a prey can account for search-image effects. In 3 experiments pigeons ate wheat and vetch grains presented on multicolored and gray gravel trays. In Experiment 1 search-image effects were evident when grains were cryptic but not when they were conspicuous. Experiment 2 demonstrated that search images can be activated when the grains encountered are either cryptic or conspicuous but that search images affect search performance only when the grains are cryptic. Experiment 3 demonstrated that search images are short-term in nature: A 3-min delay between successive encounters with a type of grain disrupted an activated search image. The discussion addresses how these results further develop a model in which search images are viewed as selective attention to visual features of a prey. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of imagery on vernier acuity under conditions of induced depth.

Imagery interferes with visual acuity (the "Perky effect") when an image is close to a visual target and both the image and the acuity target are located in the same depth plane. Whether imagery-induced interference occurs when a mental image and a target are separated by induced depth was investigated. Participants projected an image in front of or behind a vernier acuity target on a frontal or back plane suggested by the panels of an outline cube. A drop in accuracy for the target was found when an image was projected in front of, but not behind, the target. Thus, induced depth can influence the Perky effect. By contrast, real lines interfered with the target regardless of perceived depth plane, which is inconsistent with the hypothesis that imagery and perception are equivalent. Results support the hypothesis that images interfere with perception only when the participant must see through an image to obtain information specifying the visual target. (PsycINFO Database Record (c) 2010 APA, all rights reserved)