Letter Height Research Articles

Generation and perceptual implicit memory: Different generation tasks produce different effects on perceptual priming.

The generation manipulation has been critical in delineating differences between implicit and explicit memory. In contrast to past research, the present experiments indicate that generating from a rhyme cue produces as much perceptual priming as does reading. This is demonstrated for 3 visual priming tasks: perceptual identification, word-fragment completion (WFC), and word-stem completion (WSC). This result occurred regardless of the mode of study response (written or spoken) or whether the generation condition was compared with reading words in or out of context. Rhyme generation did not produce priming on the letter height task (Masson & MacLeod, 2002), implying that the effect was not mediated by covert visualization. Nor was the effect due to the mere presence of the rhyme cue. Semantic generation (from definitions) produced a different pattern, exhibiting a reverse generation effect on WFC and WSC but full (read-level) priming on perceptual identification. The present results were not consistent with accounts based on the standard transfer-appropriate processing view, covert visualization, explicit contamination, or conceptual contributions to nominally perceptual tasks.

Assessment of English Letters' Legibility Using Image Descriptors

The study derived seven descriptors from the pixel matrices of both the uppercase and lowercase forms of the 26 letters in the English alphabet in the regular and italic versions of the most commonly used font, Times New Roman. A factor analysis of the seven descriptors showed that a two-factor solution of letter width and height explained 76.6% of the variance. Legibility threshold of the 26 letters in the regular and italic Times Roman font and in two-case forms were collected to specify effects of letter width and height. 20 university students, 10 women and 10 men, with a mean age of 24.1 yr. (SD = 1.6) participated. They identified letters displayed initially on a PC screen at a minimum font size and enlarged gradually until the participant correctly recognized the letter. Analysis showed letters of greater width or height were more legible than those of smaller width or height. Given an oblique effect, letters in the italic Times Roman font had significantly greater width but were less legible than those in the regular font.

Impairment of complex upper limb motor function in de novo Parkinson's disease

The aim of the present study was to evaluate complex upper limb motor function in newly diagnosed, untreated Parkinson's disease (PD) patients. Four different unimanual upper limb motor tasks were applied to 13 newly diagnosed, untreated PD patients and 13 age- and sex-matched controls. In a handwriting task, PD patients had significantly reduced sentence length and writing velocity, and decreasing letter height in the course of writing. Furthermore, PD patients performed an aiming task slower with than without target, and showed increased transposition in a pointing task. The results of this study extend previous observations of impaired complex upper limb movements to newly diagnosed, untreated PD patients.

Effects of spatial separation between stimuli in whole report from brief visual displays

Direct measurements of the effects of spatial separation between stimuli in whole report from brief visual displays are reported. The stimuli were presented on the periphery of an imaginary circle centered on fixation. In Experiment 1, each display showed two capital letters (letter height approximately equal 1.3 degrees, width approximately equal 0.9 degree, eccentricity approximately equal 5.5 degrees). The proportion of correctly reported letters was a strictly increasing, decelerating function of the spatial separation between the letters for center-to-center separations ranging from less than 2 degrees to more than 10 degrees of visual angle. Experiment 2 yielded similar results with triples of letters. Experiment 3 showed that accuracy increased with spatial separation for report of two short words, and Experiment 4 showed the same result for words presented upside down. The results are explained by a model of lateral masking (crowding) based on competitive interactions within receptive fields of cortical neurons.

Dimensions of Good and Poor Handwriting Legibility in First and Second Graders: Motor Programs, Visual–Spatial Arrangement, and Letter Formation Parameter Setting

First and second graders who were good and poor handwriters completed three writing tasks: writing letters of alphabet in order from memory, letter copying in a passage, and composing on provided topics. A coding scheme was used to evaluate these dimensions of legibility: spacing between words and between letters within words, alignment (letter placement on lines), letter height, letter slant, reversals, added strokes, missing strokes, and missing letters. Although results were somewhat task dependent, most differences between good and poor handwriters involved poor handwriters generating more letters with added strokes, producing smaller letters, and exhibiting more variability in spacing and alignment. The good and poor handwriters did not differ on average performance in alignment of words on the baseline or in spacing of letters within words and spacing between words. Each of three dimensions of handwriting contributed uniquely to the handwriting of first and second graders: motor programs, visual-spatial arrangement on the written page, and letter formation parameter setting.

Using data visualization and signal processing to characterize the handwriting process

Disturbances in handwriting legibility and speed are found among elementary school-aged children. The aim of this paper is to present a set of sophisticated analytical tools suitable for visualization and evaluation of handwriting disturbances. Handwriting samples from 30 children, 15 proficient and 15 non-proficient handwriters, aged 8-9 years were collected with the aid of a digitizing tablet. Temporal and spatial measures of the handwriting process dynamics based on signal processing methods were developed and visually presented. Significant differences between proficient and non-proficient handwriters were found in handwriting characteristics such as the standard deviations of letter width (t=2.96, p=0.008), letter height (t=3.24, p=0.005) and pen elevation (t=2.91, p=0.008). Significant differences were also found for the number of pen lifts (t=2.27, p=0.03), for the value of the correlation coefficients between letter length and time (t= -6.62, p=0.000) and between the actual and computed number of words (t=2.79, p=0.01). The techniques described in this paper provide objective measures for handwriting performance presented in a way designed to help clinicians and educators visualize handwriting difficulties during clinical evaluation and intervention. Data visualization and analysis appear to enhance information concerning the spatial and temporal dynamics of handwriting.

Legibility Distances of Smaller Letters in Changeable Message Signs with Light-Emitting Diodes

This paper presents the results of a legibility study of 9-in. and 10.6-in. letters on changeable message signs (CMSs) with light-emitting diodes. The study, conducted in Dallas, Texas, consisted of 60 subjects, demo-graphically balanced with respect to age, gender, and education. The subjects drove a test vehicle as they approached CMSs with one of the above letter heights. Study administrators recorded the distance from the sign at which the participant could correctly read a three-letter word. Data were recorded for three trials on each of the letter heights for each participant. Data were collected during daylight (sun overhead) and nighttime conditions. The 85th percentile legibility distance for the 9-in. letter height was 228 ft for daytime conditions and 114 ft for nighttime conditions. For the 10.6-in. letter height, the 85th percentile legibility distances were 324 ft for daytime conditions and 203 ft for nighttime conditions, respectively. The 85th percentile legibility distances for each letter height were used to estimate available viewing times under various approach speeds. These available viewing times dictate the units of information that can be presented on a CMS of a particular letter size.

Legibility Distances of Smaller Letters in Changeable Message Signs with Light-Emitting Diodes

This paper presents the results of a legibility study of 9-in. and 10.6-in. letters on changeable message signs (CMSs) with light-emitting diodes. The study, conducted in Dallas, Texas, consisted of 60 subjects, demographically balanced with respect to age, gender, and education. The subjects drove a test vehicle as they approached CMSs with one of the above letter heights. Study administrators recorded the distance from the sign at which the participant could correctly read a three-letter word. Data were recorded for three trials on each of the letter heights for each participant. Data were collected during daylight (sun overhead) and nighttime conditions. The 85th percentile legibility distance for the 9-in. letter height was 228 ft for daytime conditions and 114 ft for nighttime conditions. For the 10.6-in. letter height, the 85th percentile legibility distances were 324 ft for daytime conditions and 203 ft for nighttime conditions, respectively. The 85th percentile legibility distances for each letter height were used to estimate available viewing times under various approach speeds. These available viewing times dictate the units of information that can be presented on a CMS of a particular letter size.

An evaluation of the lag of accommodation using photorefraction

Objective. The lag of accommodation which occurs in most human subjects during reading has been proposed to explain the association between reading and myopia. However, the measured lags are variable among different published studies and current knowledge on its magnitude rests largely on measurements with the Canon R-1 autorefractor. Therefore, we have measured it with another technique, eccentric infrared photorefraction (the PowerRefractor), and studied how it can be modified. Methods. Particular care was taken to ensure correct calibration of the instrument. Ten young adult subjects were refracted both in the fixation axis of the right eye and from the midline between both eyes, while they read text both monocularly and binocularly at 1.5, 2, 3, 4 and 5 D distance (“group 1”). A second group of 10 subjects (“group 2”), measured from the midline between both eyes, was studied to analyze the effects of binocular vs monocular vision, addition of +1 or +2 D lenses, and of letter size. Spherical equivalents (SE) were analyzed in all cases. Results. The lag of accommodation was variable among subjects (standard deviations among groups and viewing distances ranging from 0.18 to 1.07 D) but was significant when the measurements were done in the fixation axis (0.35 D at 3 D target distance to 0.60 D at 5 D with binocular vision; p<0.01 or better all cases). Refracting from the midline between both eyes tended to underestimate the lag of accommodation although this was significant only at 5 D (ANOVA: p<0.0001, post hoc t-test: p<0.05). There was a small improvement in accommodation precision with binocular compared to monocular viewing but significance was reached only for the 5 D reading target (group 1––lags for a 3/4/5 D target: 0.35 vs 0.41 D/0.48 vs 0.47 D/0.60 vs 0.66 D, ANOVA: p<0.0001, post hoc t-test: p<0.05; group 2––0.29 vs 0.12 D, 0.33 vs 0.16 D, 0.23 vs −0.31 D, ANOVA: p<0.0001, post hoc t-test: p<0.05). Adjusting the letter height for constant angular subtense (0.2 deg) induced scarcely more accommodation than keeping letter size constantly at 3.5 mm (ANOVA: p<0.0001, post hoc t-test: n.s.). Positive trial lenses reduced the lag of accommodation under monocular viewing conditions and even reversed it with binocular vision. Conclusions. After consideration of possible sources of measurement error, the lag of accommodation measured with photorefraction at 3 D (0.41 D SE monocular and 0.35 D SE binocular) was in the range of published values from the Canon R-1 autorefractor. With the measured lag, simulations of the retinal images for a diffraction limited eye suggest surprisingly poor letter contrast on the retina.

Letter Legibility for Signs and Other Large Format Applications

Numerous studies have evaluated the legibility of various fonts displayed in small print. There has also been a great deal of research into the legibility and recognition of standard highway sign alphabets. There has, however been no attempt to empirically determine large format distance legibility for the growing number of fonts currently available to non-transportation sign manufacturers. The present study systematically evaluated the letter legibility of a set of fonts that are consistent with commercial (e.g., storefront), industrial, transit, and highway signage. The fonts were evaluated in a laboratory setting. Individual test charts were designed for each of the fonts based on the standard Snellen distance visual acuity chart. Recognition acuity thresholds for each of the fonts yielded the minimum visual angle of letter height necessary for their resolution. The relative legibility of each font is discussed, as is the effect of font choice on sign size, and theoretical issues related to critical detail for letter recognition acuity.

Legibility Threshold Contrast of Uppercase Text Seen against a Dark Background

A laboratory experiment was conducted to determine the effects of letter height, letter width-to-height ratio, stroke width-to-height ratio, inter-character spacing-to-height ratio, on the legibility of uppercase single words displayed in an achromatic, positive contrast polarity. Legibility was investigated in terms of threshold contrast. A total of 10 young, healthy subjects participated in the experiment which was conducted under carefully controlled conditions in a dark tunnel. A substantial amount of legibility optimization research on individual typographical parameters is found in the technical literature. However, no studies were located that simultaneously investigated the letter-height, the width/height ratio, the stroke-width/height ratio, and the spacing/height ratio in a full factorial experiment such as the one presented in this paper. The presented data can be used to optimize the legibility of uppercase, single words made up by the standard highway alphabet subject to sign size constraints.

Evaluation of Prototype Highway Tourist Signs for Ontario

Information load and comprehension of new tourist signs for Ontario highways were evaluated. In a laboratory study involving 288 subjects, drivers searched for target destinations on timed sequences of slides of signs and identified whether their target was present, and, if so, its direction and distance. Performance was assessed in relation to number of names, number of signs in a sequence, arrow shapes, pictograph effectiveness, and sign organization. Signs used a letter height of 19 cm (7.5 in.). Subjects were allowed reading time equivalent to that available to drivers driving at 80 km/h (50 mph), who must time-share sign reading and vehicle control tasks. The results showed that with four or five names per sign, approximately one in eight subjects reported an incorrect direction for their target destination. Thus, a maximum of three names per sign was recommended. Results showed that a 70-degree chevron was as effective as a gerber arrow, that the number of signs in a sequence (two, three, or four) did not affect performance, and that having left followed by right destinations on a single sign resulted in equivalent performance to signs with left and right destinations on separate signs. The presence of pictographs increased the number of incorrect responses. Comprehension of 11 pictographs was assessed for 150 subjects. For 5 of 11 pictographs, comprehension was less than 85 percent.

Interaction of screen distances, screen letter heights and source document distances

An experiment was conducted to investigate the main and interaction effects of screen distances (600 mm and 900 mm), screen letter heights (for visual angles of 16, 20, and 30 minutes of arc), and source document distances (same as the screen distance and closer than the screen distance) on visual performance and subjective preference in text proofreading tasks. Thirty subjects in different age groups participated in the experiment. The experimental results revealed that the subjects' performance improved from the letter height of 16 minutes of arc to the letter height of 20 minutes of arc for the 600 mm screen distance, but from 20 minutes of arc to 16 minutes of arc for the 900 mm screen distance. The subjects generally preferred a screen distance slightly higher than 600 mm, a letter height at the 22 minutes of arc, and a small difference between the visual angle of screen letters and the visual angle of source letters.

Effects of selective attention on spatial form processing in monkey primary and secondary somatosensory cortex.

1. The effects of selective attention were studied in SI and SII cortex of a rhesus monkey trained to perform two tasks, a tactile discrimination task and a visual detection task. In the tactile task, a letter was displayed on a video screen in front of the monkey and the animal was rewarded for responding when the raised letter (6.0 mm letter height) scanning across its finger (15 mm/s) matched the letter on the screen. In the visual task, three illuminated squares were displayed on the screen, and the animal was rewarded for detecting when one of the squares dimmed. The neural responses evoked by the raised letters were recorded continuously while the animal's focus of attention was switched back and forth between the two tasks. 2. Significant differences between the discharge rates evoked by raised letters in the two tasks were observed in approximately 50% of neurons in SI cortex and 80% of neurons in SII cortex. The effects in SII cortex were divided between increased (58%) and decreased (22%) rates. In SI cortex only increased rates were observed. 3. The attentional effects were expressed not only as changes in overall neuronal activity but also as modifications of the form of the responses evoked by the letters. 4. Whether attentional effects were observed depended upon the behavioral relevance of individual letters. During brief periods in the tactile task when a behavioral response could not yield a reward (time-out and reward periods) the neuronal responses were not significantly different from the responses evoked by the same letters during the visual task.(ABSTRACT TRUNCATED AT 250 WORDS)

Object spatial frequencies, retinal spatial frequencies, noise, and the efficiency of letter discrimination

To determine which spatial frequencies are most effective for letter identification, and whether this is because letters are objectively more discriminable in these frequency bands or because can utilize the information more efficiently, we studied the 26 upper-case letters of English. Six two-octave wide filters were used to produce spatially filtered letters with 2D-mean frequencies ranging from 0.4 to 20 cycles per letter height. Subjects attempted to identify filtered letters in the presence of identically filtered, added Gaussian noise. The percent of correct letter identifications vs sn (the root-mean-square ratio of signal to noise power) was determined for each band at four viewing distances ranging over 32:1. Object spatial frequency band and sn determine presence of information in the stimulus; viewing distance determines retinal spatial frequency, and affects only ability to utilize. Viewing distance had no effect upon letter discriminability: object spatial frequency, not retinal spatial frequency, determined discriminability. To determine discrimination efficiency, we compared human discrimination to an ideal discriminator. For our two-octave wide bands, sn performance of humans and of the ideal detector improved with frequency mainly because linear bandwidth increased as a function of frequency. Relative to the ideal detector, human efficiency was 0 in the lowest frequency bands, reached a maximum of 0.42 at 1.5 cycles per object and dropped to about 0.104 in the highest band. Thus, our subjects best extract upper-case letter information from spatial frequencies of 1.5 cycles per object height, and they can extract it with equal efficiency over a 32:1 range of retinal frequencies, from 0.074 to more than 2.3 cycles per degree of visual angle.

Effects of a self-instructional procedure on handwriting.

A card showing seven self-instructional questions designed to prompt students to think about important aspects of handwriting was provided to two learning disabled elementary school boys according to a multiple baseline design. Assessments of the boys' handwriting performance, including letter formation, letter proximity to the line, letter height, and word spacing were made daily in their resource room. The assessment data showed that (a) the boys' handwriting improved markedly when the card was introduced, (b) the improvements persisted over time while the card was still available to them, and (c) the effects were maintained even after the card was no longer available. Data from the regular classroom for one of the boys showed that his handwriting also improved in that setting.

Image and Perceptual Representation of Words in Learning Disabled and Normal Children

Results of the present study indicated that learning disabled and normal children (x age = 111.4 months) process letters in words in either perceptual or imaginal modes for the attribute letter height. A large processing time effect was noted for mode of representation with perceptual representations of letters processed more rapidly than imaginal representations. There was also a subject-type-by-processing mode interaction. The results indicate that LD and normal children do not differ in perceptual processing time; however, LD children have a smaller image capacity than normals. Correlational results also suggest that the imaginal mode is more independent of other modes for normals than for LDs.

Letter Size and Legibility

The legibility of displayed letters depends upon their size, or more accurately, their subtended visual angle at any viewing distance. Current design standards recommend letter heights in the range from 0.003 to 0.007 rad (10 to 24 mill of arc) for good viewing conditions, with 0.0015 rad (5 min) considered a lower limit based on normal visual acuity. A field study involving some 2000 measures for over 300 printed displays found a mean letter height of 0.0019 rad (7 min) at the limit of legibility, with over 90% legibility at 0.003 rad and virtually 100% at 0.007 radians.

Type-Size Variability for Near-Point Acuity Tests

We measured the sizes of the test forms (letters, digits, and symbols) on 19 different near-point acuity cards. The results are all expressed in the M notation (1 mm of letter height equals 0.7 M) and are tabled according to the acuity specification system used by the manufacturers--such as, the point-type system, Jaeger notation, equivalent 20-ft Snellen notation, and so on. Our results demonstrate that manufacturer's specifications on near-point acuity cards cannot be used to determine the sizes of test letters. The M system has sufficient advantages over other systems to warrant its universal use for specifying near-point visual acuity.

Inscriptions from Pamphylia and Isauria

Sillyon. Note on an inscription already publishedCIG iii. 4324c = SGDI 1268. This inscription is carved in a panel on a rock to the west of the city, near the modern village. Height ·16 m., breadth ·175, letter and space down ·026, letter and space across ·019Perhaps [Όλυμ]πιακοῦ, since ἱαρός can be used in connexion with the Games, as in Lanckoroński, Städte Pämphyliens und Pisidiens, i, p. 66; but the meaning is uncertain; ἱερά generally means ‘a dead-heat’ (LSJ ἱερός iv. 7).Sillyon. New inscriptions(1) A statue-base, near the Byzantine wall. Grey stone, the top and the lower part of the left side are preserved. The bottom is buried and the back is very rough, but may be original. Height over ·7, breadth c. ·65, thickness ·33+, letter height c. ·058, letter and space across ·056. Roman date.