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PubMed1992

Hemispheric priming by meaningful and nonmeaningful symbols in language-trained chimpanzees (Pan troglodytes): further evidence of a left hemisphere advantage.

Hemispheric priming was examined in 3 language-trained chimpanzees (Pan troglodytes) using a simple reaction time paradigm. Subjects were required to hold down a response button until the occurrence of a response cue. A warning stimulus was presented to either the left visual field (LVF) or the right visual field (RVF) before the response cue occurred. No warning stimulus was presented on control trials. The warning stimuli were geometric communicative symbols from two semantic categories: foods and tools. A third set of warning stimuli were familiar geometric symbols. Dependent measures included reaction time and the number of false-positive responses. Reaction-time data indicated an RVF advantage in priming when the warning stimuli were food or tool symbols. No significant visual half-field differences were found for familiar symbols, but a trend toward an RVF advantage was observed. These effects were enhanced when subjects responded with their left hand. False-positive data also indicated an RVF advantage for the food and tool warning stimuli. The data indicate that hemispheric asymmetries for processing communicative symbols are present in language-trained chimpanzees.

Animals↗
PubMed1981

Learning words using traditional orthography and the symbols of Rebus, Bliss and Carrier.

This study compared the learning of words represented in traditional orthography (T.O.) and in the logographic symbols of Rebus, Bliss, and Carrier. Subjects, 36 preschool children ages 4.3 to 5.4, were presented a short task requiring the learning of 15 words in one of the four graphic conditions, Rebus, Bliss, Carrier, to T.O. The results showed that the logographic symbols as a group were significantly easier to learn than T.O., the partially iconic systems of Rebus and Bliss were significantly easier to learn than the Carrier symbols, and Rebus symbols were significantly easier to learn than Bliss symbols. Implications for the instructional use of logographic systems are discussed.

Child Language↗
PubMed1995

Ocular measures of redundancy gain during visual search of colour symbolic displays.

Sixteen observers participated in a visual search experiment in which colour coding, search type, and the amount of pre-search information available to the observers were varied. Observers searched simulated symbolic tactical displays to find the number of target symbols (i.e. exhaustive search) or the quadrant of the display in which a single target symbol was located (i.e. self-terminating search). Displays varied in the way in which the symbology was colour coded: colour was either relevant (i.e. redundant with symbol shape) or irrelevant (orthogonal to symbol shape), or the display was monochrome. Half of the observers were cued with regard to the coding scheme prior to display onset, while the other observers were not. There was no overall difference in search time or accuracy, number of eye fixations, or pupillary response between cued and non-cued observers, but only because cued and non-cued observers used the coding schemes differently. Redundancy gain was only evident for cued observers, who searched colour relevant displays faster and with fewer fixations than colour irrelevant or monochrome displays. Non-cued observers' search pattern did not differ across colour coding schemes, but they searched colour irrelevant and monochrome displays faster than the cued observers. Differences between cued and non-cued observers' search strategy are discussed with regard to their implications for design and evaluation of colour multipurpose displays.

Adult↗
PubMed2002

Cultural ergonomics in Ghana, West Africa: a descriptive survey of industry and trade workers' interpretations of safety symbols.

Globalization and technology transfer have led to the diffusion of risk communications to users from cultures that were not initially viewed as the target users. This study examined industry and trade workers' overall impressions of symbols used to convey varying degrees of hazardousness. Six symbols, including symbols from the American National Standards Institute (ANSI) Z535 Standard (ANSI, 1998) and the International Organization for Standardization (ISO) 3864:1984 Standard (ISO, 1984) were selected. With the exception of the SKULL symbol, results showed wide discrepancies between users' perceptions of the symbols and their intended meanings. Implications for cross-cultural research on warning components and risk communications are discussed.

Accidents, Occupational↗
PubMed1978

The role of memory in the age decline in digit-symbol substitution performance.

Adult age differences in the Digit Symbol Test were investigated in three separate experiments. All experiments incorporated a manipulation of the number of digit-symbol pairs in modified versions of the test forms to determine whether the age differences would be reduced with decreased memory requirements. The results of all three experiments indicated that, as the number of digit-symbol pairs was reduced, the age difference was reduced in absolute terms, but not in relative terms. Older subjects decreased their times by greater absolute amounts, but by the same relative amounts when the number of digit-symbol pairs was decreased from nine to one. Independent results supported the interpretation that memory factors play a very small role in contributing to the age decline in digit-symbol performance.

Adult↗
PubMed1995

Performance on the digit symbol substitution test and 5-year mortality in the Western Collaborative Group Study.

The relation between performance on the digit symbol substitution test and subsequent 5-year mortality was examined in 1,118 male participants in the Western Collaborative Group Study (mean age at time of examination = 70.6 years). Cox regression analyses revealed that the unadjusted relative risk from all-cause mortality was 1.79 (95% confidence interval 1.45-2.21) for subjects who scored 10 points (1 standard deviation) lower on the digit symbol substitution test. The relative risk remained significant at 1.44 (95% confidence interval 1.12-1.86) after adjustment for age, education, baseline serum cholesterol, and systolic blood pressure levels and for the prevalence of cancer, cardiovascular/cerebrovascular disease, and ever smoking. Tree-structured survival analysis revealed the presence of a subgroup of subjects (n = 130) with low digit symbol substitution performance (mean = 26.3) who experienced a mortality rate of 34.9 deaths per 1,000 person-years. This mortality rate was not significantly different from that encountered by another subgroup of subjects with a history of cancer (n = 128; 45.7 deaths per 1,000 person-years). If age-related slowing of information processing is a marker for aging of the central nervous system, then people with lower digit symbol scores may be "older" physiologically than similarly aged persons with higher digit symbol scores. Aging of the central nervous system might be expected to reduce adaptive capacity in a general way, thereby increasing susceptibility to death from a variety of causes.

Aged↗
PubMed2003

Visual acuity results in school-aged children and adults: Lea Symbols chart versus Bailey-Lovie chart.

PURPOSE: To compare visual acuity results obtained using the Lea Symbols chart with visual acuity results obtained with the Bailey-Lovie chart in school-aged children and adults using a within-subjects comparison of monocular acuity results. METHODS: Subjects were 62 individuals between 4.5 and 60 years of age, recruited from patients seen in five optometry clinics. Each subject had acuity of the right eye and the left eye tested with the Lea Symbols chart and the Bailey-Lovie chart, with order of testing varied across subjects. Outcome measures were monocular logarithm of the minimum angle of resolution (logMAR) visual acuity and inter-eye acuity difference in logMAR units for each test. RESULTS: Correlation between acuity results obtained with the two charts was high. There was no difference in absolute inter-eye acuity difference measured with the two acuity charts. However, on average, Lea Symbols acuity scores were one logMAR line better than Bailey-Lovie acuity scores, and this difference increased with worse visual acuity. CONCLUSIONS: The Lea Symbols chart provides a measure of inter-eye difference that is similar to that obtained with the Bailey-Lovie chart. However, the monocular acuity results obtained with the Lea Symbols chart differ from those obtained with the Bailey-Lovie chart, and the difference is dependent on the individual's absolute level of visual acuity.

Adolescent↗
PubMed2004

Preschool visual acuity screening with HOTV and Lea symbols: testability and between-test agreement.

PURPOSE: To compare the performance of 3- to 5-year-old children on visual acuity screening with HOTV letters vs. Lea symbols as optotypes. METHODS: Subjects included 1253 Head Start children who were aged either 3 or 4 years on September 1 of the school year of testing. The sample over-represented children who had not passed a Head Start screening. Binocular pretesting at 1 m demonstrated the child's ability to identify the optotypes verbally or by matching optotypes on a lap card. Acuity was tested monocularly at 3 m using crowded single lines of optotypes. Lines tested were based on age at the beginning of the school year (September 1) with 3-year-old children tested with lines 10/100, 10/32, 10/25, and 10/20 and 4-year-old children tested with 10/100, 10/25, 10/20, and 10/16. RESULTS: Overall, 99% of children were able to complete the binocular pretest for each test successfully, and there was no difference between the tests (p = 0.83). Children's ability to complete the pretest increased slightly with age. HOTV test scores were slightly worse than Lea symbols test scores (p = 0.047), primarily because more children were unable to pass the monocular 10/100 card for the HOTV test than for the Lea symbols test (2.6% vs. 1.3%). The percentage of identical results on HOTV vs. Lea overall was 67.3% and increased significantly with age. When the results were different, 3-year-old children, but not 4- and 5-year-old children, tended to have worse results on the HOTV letter test. CONCLUSIONS: The vision of nearly all 3- to 5-year-old children can be screened using either HOTV letters or Lea symbols. HOTV letters may be slightly more difficult than Lea symbols for 3- to 5-year-old children, with the largest difference between acuity results on the two tests occurring in 3-year-old children.

Aging↗
PubMed2003

Dressed symbolic dynamics.

A strange attractor (SA) with symmetry group G can be mapped down to an image strange attractor SA without symmetry by a smooth mapping with singularities. The image SA can be lifted to many distinct structurally stable strange attractors, each equivariant under G, all with the same image SA. If the symbolic dynamics of the image SA requires s symbols sigma(1),sigma(2), em leader,sigma(s), then |G|s symbols are required for symbolic dynamics in the covers, and there are |G|(s) distinct equivariant covers. The covers are distinguished by an index. The index is an assignment of a group operator to each symbol sigma(i):sigma(i)-->g(alpha(i)). The subgroup H subset G generated by the group operators g(alpha(i)) in the index determines how many disconnected components (|G|/|H|) each equivariant cover has. The components are labeled by coset representatives from G/H. The structure of each connected component is determined by H. A simple algorithm is presented for determining the number and the period of orbits in an equivariant attractor that cover an orbit of period p in the image attractor. Modifications of these results for structurally unstable covers are summarized by an adjacency diagram.

Journal Article↗
PubMed2006

Unified system of Hermann-Mauguin symbols for groups of material physics. 1. Groups with decomposable lattices.

The system of Hermann-Mauguin symbols for space and subperiodic Euclidean groups in two and three dimensions is extended to groups with continuous and semicontinuous translation subgroups (lattices). An interpretation of these symbols is proposed in which each symbol defines a quite specific Euclidean group with reference to a crystallographic basis, including the location of the group in space. Symbols of subperiodic (layer and rod) groups are strongly correlated with symbols of decomposable space groups on the basis of the factorization theorem. Introduction of groups with continuous and semicontinuous lattices is connected with a proposal for several new terms that describe the properties of these groups and with a proposal to amend the meaning of space groups and of crystallographic groups. Charts of plane, layer and space groups describe variants of these groups with the same reducible point group but various types of lattices. Examples of such charts are given for plane, layer and space groups to illustrate the unification principle for groups with decomposable lattices.

Journal Article↗
PubMed2006

Transformational space-group symbols.

Ambiguities present in space-group construction from the Hermann-Mauguin (H-M) symbols enforce the use of other space-group designations or H-M symbol modifications. Therefore, a transformational space-group symbol (TSG) composed of the well defined standard space-group identifier, an axis-system transformation and origin shift is proposed as a symbol of any space-group description. The first description given in International Tables for Crystallography [(1983), Vol. A, Space-Group Symmetry, edited by Th. Hahn. Dordrecht: Reidel (ITA83)] or the second one for space groups with two origins is suggested here as a reference description. For standard descriptions based on the ITA generators and compiled list of the TSG symbols, all conventional space-group settings listed in ITA83 can be reconstructed.

Crystallography, X-Ray↗
PubMed2005

Short- and long-term joint symbolic dynamics of heart rate and blood pressure in dilated cardiomyopathy.

Autonomic cardiovascular control involves complex interactions of heart rate and blood pressure. In patients with dilated cardiomyopathy (DCM), this control is impaired and parameters for its quantification might be of prognostic importance. In this paper, we introduce methods based on joint symbolic dynamics (JSD) for the enhanced analysis of heart rate and blood pressure interactions. To assess the coarse-grained dynamics beat-to-beat changes of heart rate and blood pressure are encoded in symbol strings. Subsequently, the distribution properties of short symbol sequences (words) as well as the scaling properties of the whole symbol string are assessed. The comparison of joint symbolic heart rate and blood pressure dynamics in DCM (n = 75) with those in healthy controls (n = 75) showed significant changes. Both, the distribution of words and the scaling properties indicate a loss in heart rate dynamics associated with blood pressure regulation in DCM. In conclusion, the analyses of short- and long-term JSDs provide insights into complex physiological heart rate and blood pressure interactions and furthermore reveal patho-physiological cardiovascular control in DCM.

Blood Pressure↗
PubMed1993

Redundant use of luminance and flashing with shape and color as highlighting codes in symbolic displays.

Three visual search experiments evaluated the benefits and distracting effects of using luminance and flashing to highlight subclasses of symbols coded by shape and color. Each of three general shape/color classes (circular/blue, diamond/red, square/yellow) was divided into three subclasses by presenting the upper half, lower half, or entire symbol. Increasing the luminance of a subclass by a factor of two did not result in a significant improvement in search performance. Flashing a subclass at a rate of 3 Hz resulted in a significantly shorter mean search time (48% improvement). Increasing the luminance of one subclass (by a factor of five) while simultaneously flashing another significantly improved search times by 31% and 43% respectively, compared with nonhighlighted search conditions. In each experiment, the search times for nonhighlighted target subclasses were not affected by the presence of brighter and flashing targets. The failure of the initial experiment to find a significant performance improvement caused by increasing symbol luminance suggested that a larger luminance increase was necessary for this code to be effective. The overall results suggest that using luminance and flashing to highlight subclasses of color- and shape-coded symbols can reduce search times for these subclasses without producing a distraction effect by way of a concomitant increase in the search times for unhighlighted symbols.

Adult↗
PubMed1979

Feasibility of symbolic directions on prescription labels.

This project presents the results of a study designed to evaluate the usefulness of graphic labels in assisting functionally illiterate patients to understand how and when to take medication. The project's results indicate that comprehension of symbolic directions did not increase as rapidly as comprehension of typed directions. Symbolic directions did, however, reduce the variation in interpretation of directions among patients with 0-4 grade education. Neither age, nor sex, nor the order of label presentation affected level of comprehension of typed or symbolic prescription labels. The results of this study indicate that use of symbols may not be the sole answer to the problem of assisting patients with inadequate reading abilities. Symbolic prescription directions should be evaluated before their use. Then, when used, they should be accompanied by oral reinforcement.

Adult↗
PubMedDate not supplied

Comparison of the HOTV and Lea Symbols charts for preschool vision screening.

PURPOSE: Two preliterate acuity charts, the Lea Symbol chart and the HOTV chart, were compared prospectively in an established preschool vision screening program. The charts were compared by measuring time required to test, reliability coefficients, and the percentage of children testable with each chart. METHODS AND MATERIALS: Seven hundred and seventy-seven 3- to 5-year-old children were randomized to four screening sequences that determined the order of chart use. Each child was screened on two occasions within 6 weeks. Testing was performed at 10 feet, and optotypes were not isolated for testing. RESULTS: Mean test time was significantly less for older children, but was not related to the chart used. Reliability coefficients were similar for the Lea Symbols and the HOTV charts. The percentage of children testable by each chart improved with increased age of the child. More 3 year olds were testable with the Lea Symbols chart compared to the HOTV chart (92% versus 85%, P = .05). CONCLUSIONS: Vision screening with either chart was more rapid and more frequently achieved with 4- and 5-year-old children compared with the 3 year olds. For the population as a whole, each chart gave similar results. Among the 3 year olds, however, testability rates were better for the Lea Symbols chart. The Lea Symbols chart is an acceptable option for preschool vision screening, and may be more efficacious than the HOTV chart for screening 3-year-old children.

Child, Preschool↗
PubMedDate not supplied

Comparison of the HOTV and Lea symbols visual acuity tests in patients with amblyopia.

PURPOSE: To determine whether the Lea symbols visual acuity test, compared with the HOTV visual acuity test, overestimates visual acuity in patients with amblyopia. PATIENTS AND METHODS: Fifty-nine patients with amblyopia or a history of amblyopia treatment had visual acuity measurements in both eyes with the HOTV and Lea symbols tests. Crowding bars, separated by a width of 1 optotype, and the original pilot-testing protocol in the Amblyopia Treatment Study were used to quantify visual acuity. RESULTS: The patients' ages ranged from 4 to 35 years (mean age, 10.1 years). Visual acuity in the amblyopic eyes ranged from 20/20 to 20/250. The mean visual acuity difference (HOTV scores vs Lea symbols scores) was -0.056 logMAR units (P < .001), slightly more than half of a line. The negative value indicates that patients performed better on the HOTV test. In nonamblyopic eyes, the mean difference was -0.05 logMAR units (P < .001). Patients with strabismic amblyopia had a mean difference of -0.05 logMAR units (P = .08); those with anisometropic amblyopia had a mean difference of -0.07 logMAR units (P = .002). Patients 8 years and younger had a mean difference of -0.04 logMAR units (P = .05); those older than 8 years had a mean difference of -0.06 logMAR units (P = .002). CONCLUSIONS: In both amblyopic and nonamblyopic eyes, visual acuity measurements were better on HOTV testing compared with Lea symbols testing. The differences persisted regardless of patient age and the cause and severity of amblyopia. Overestimation of visual acuity by the Lea symbols test was not found.

Adolescent↗
PubMed1987

Patterns of symbolic expression in subgroups of the childhood psychoses.

Differential patterns of symbolic expression, through the modalities of language, gesture, play, and drawing, were investigated in 48 psychotic children: 26 with chart diagnoses of autism and 22 with chart diagnoses of schizophrenia. As predicted, autistic children tended to show an absence of symbol use, while schizophrenic children demonstrated complex or differentiated symbol use. A multiple discriminant analysis supported the hypothesized emergence of a "transitional" group of children, defined on the basis of echolalic language, who showed stereotypic or undifferentiated symbol use.

Autistic Disorder↗
PubMed1993

Symbolic play in autism: a review.

Experimental research into the symbolic play of autistic children is reviewed in an attempt to outline the nature of their deficit in this area. While many studies can be criticized on methodological grounds, there is good evidence for an impairment in the spontaneous symbolic play of autistic children, an impairment that appears to extend to cover spontaneous functional play also. However studies that have investigated elicited and instructed play have indicated that autistic children may have a capacity for symbolic play that they do not spontaneously exhibit. The implications of these findings for various hypotheses concerning a symbolic play deficit in autism are considered and directions for future research are outlined.

Autistic Disorder↗