What various kinds of errors tell us about lateral masking effects

Huckauf, Anke; Heller, Dieter

doi:10.1080/13506280143000548a

Cited by 51 publications

(77 citation statements)

References 16 publications

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“…Several studies have shown that mislocation errors (i.e., reporting another letter in the stimulus string) can account for some of the reduced performance in crowding tasks (Fine, 2001;Huckauf & Heller, 2002a, 2002b. To determine whether mislocation errors varied depending on stimulus type, a 2 (group) ϫ 2 (location) ϫ 2 (stimulus type) ϫ 2 (error position: left or right of the target) ANOVA was calculated.…”

Section: Resultsmentioning

confidence: 99%

“…Eriksen and Eriksen (1974) concluded that increased spacing between letters improved performance in a letter search task, at least in part because it improved the observer's ability to select the target from among the distractors. This should result in fewer positional errors as spacing is increased and a further reduction in the impact of crowding (Huckauf & Heller, 2002b). However if the conclusions drawn above are correct, there should be little or no change in the benefit of word context when crowding is reduced.…”

Section: Methodsmentioning

confidence: 99%

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The relative benefit of word context is a constant proportion of letter identification time

Fine

2004

Perception & Psychophysics

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Letter identification is reduced when the target letter is surrounded by other, flanking letters. This visual crowding is known to be impacted by physical changes to the target and flanks, such as spatial frequency content, polarity, and interletter spacing. There is also evidence that visual crowding is reduced when the flanking letters and the target letter form a word. The research reported here investigated whether these two phenomena are independent of each other or whether the degree of visual crowding impacts the benefit of word context. Stimulus duration thresholds for letters presented alone and for the middle letters of 3-letter words and nonwords were determined for stimuli presented at the fovea and at the periphery. In Experiment 1, the benefit of word context was found to be the same at the fovea, where visual crowding is minimal, and at the periphery, where visual crowding is substantial. In Experiment 2, visual crowding was manipulated by changing the interletter spacing. Here, too, the benefit of word context was fairly constant for the two retinal locations (fovea or periphery), as well as with changes in interletter spacing. These data call into question both the idea that the benefit of word context is greater when stimulus quality is reduced (as is the case with visual crowding) and the idea that words are processed more effectively when they are presented at the fovea.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The relative benefit of word context is a constant proportion of letter identification time

Fine

2004

Perception & Psychophysics

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“…For example, imprecise letter position coding could result from attentional disturbances or increased crowding effects in dyslexia. Huckauf and Heller (2002) demonstrated that crowding effects could be explained by position uncertainty rather than interactions of adjacent letter forms. Teasing apart letter position coding and crowding effects on dyslexic reading would require further study by independently manipulating print size and letter spacing.…”

Section: Discussionmentioning

confidence: 99%

The effect of print size on reading speed in dyslexia

O’Brien

Mansfield

Legge

2005

Journal Research in Reading

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This article details a study which predicted that across a wide range of print sizes dyslexic reading would follow the same curve shape as skilled reading, with constant reading rates across large print sizes and a sharp decline in reading rates below a critical print size. It also predicted that dyslexic readers would require larger critical print sizes to attain their maximum reading speeds, following the letter position coding deficit hypothesis. Reading speed was measured across twelve print sizes ranging from Snellen equivalents of 20/12 to 20/200 letter sizes for a group of dyslexic readers in Grades 2 to 4 (aged 7 to 10 years), and for non-dyslexic readers in Grades 1 to 3 (aged 6 to 8 years). The groups were equated for word reading ability. Results confirmed that reading rate-by-print size curves followed the same two-limbed shape for dyslexic and non-dyslexic readers. Dyslexic reading curves showed higher critical print sizes and shallower reading rate-by-print size slopes below the critical print size, consistent with the hypothesis of a letter-position coding deficit. Non-dyslexic reading curves also showed a decrease of critical print size with age. A developmental lag model of dyslexic reading does not account for the results, since the regression of critical print size on maximum reading rate differed between groups.Developmental dyslexia, a learning disability specific to reading, affects an estimated 5% of children in school. Reading requires processing of both the visual information from the page and the linguistic information that the print represents. Over a century of research on causal factors in developmental dyslexia has emphasised either one or the other of these processes, beginning with theories of visual causation. Morgan (1896) coined the inability to read in children as 'congenital word blindness ', while Orton (1928) described the phenomenon of 'strephosymbolia' (twisted symbols), where children could read mirror-image writing more easily. The current view of dyslexia holds that reading failure is caused by a linguistic deficit in coding phonemes (individual speech sounds) within words, and thereby in accessing and manipulating these phonemic codes as required on a wide range of tasks (phonological processing) (Snowling, 2000). This view holds that a phonological processing deficit impedes a child's ability to develop phoneme awareness, to learn grapheme-phoneme correspondence rules, and to decode words (Liberman et al., 1974;Stanovich & Siegel, 1994). The theory accounts for many cases of developmental dyslexia, but there are individuals with dyslexia who do not demonstrate a severe phonological deficit (Wolf & Bowers, 1999;Lovett, Steinbach & Frijters, 2000). Also, remediation programmes aimed at training phonological skills are often but not entirely successful (Lyon & Moats, 1997;Torgesen, 2000). This suggests a need for alternative or additional accounts of causal factors in dyslexia. Recent evidence shows that subtle impairments in visual processing characterise some...

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“…Thus, the recognition mechanisms seem to be similar for stimuli at the fixation depth in both studies, whereas our study shows that processing in defocused depths might be different. It is assumed that positional uncertainty plays a substantial role in crowding effects (Huckauf and Heller, 2002a;2002b). Strasburger (2005) claimed that especially imprecision in spatial attention are responsible for that.…”

Section: Discussionmentioning

confidence: 99%

“…Crowding also varies with spacing: increasing the spacing between target and flankers results in increasing target recognisability, that is, in decreased crowding. To which extent target selection processes contribute to crowding is under discussion (e.g., Huckauf and Heller, 2002a;2002b;Strasburger et al, 2011;Strasburger and Malania, 2013). Bouma (1970) found that target eccentricity and spacing interact.…”

Section: Introductionmentioning

confidence: 99%