Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SYMBOLISM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources
PubMed2004

Adult age and digit symbol substitution performance: a meta-analysis.

This article reports the results of a meta-analysis of the effects of age, education, and estimated year of measurement on scores from the Wechsler Adult Intelligence Scale and the Wechsler Adult Intelligence Scale-Revised Digit Symbol Substitution Test. Analysis of effect sizes for age reported in 141 studies published between 1986 and 2002 indicated a mean standardized difference of -2.07. Age accounted for 86% of the variance in a regression model using age, education, and year submitted as predictors of Digit Symbol scores. There was no association between years of education or year submitted and Digit Symbol scores for younger adults or older adults.

Adult↗
PubMed2006

Developmental memory capacity resources of typical children retrieving picture communication symbols using direct selection and visual linear scanning with fixed communication displays.

PURPOSE: This study examined the cognitive demands of 2 selection techniques in augmentative and alternative communication (AAC), direct selection, and visual linear scanning, by determining the memory retrieval abilities of typically developing children when presented with fixed communication displays. METHOD: One hundred twenty typical children from kindergarten, 1st, and 3rd grades were randomly assigned to either a direct selection or visual linear scanning group. Memory retrieval was assessed through word span using Picture Communication Symbols (PCSs). Participants were presented various numbers and arrays of PCSs and asked to retrieve them by placing identical graphic symbols on fixed communication displays with grid layouts. RESULTS: The results revealed that participants were able to retrieve more PCSs during direct selection than scanning. Additionally, 3rd-grade children retrieved more PCSs than kindergarten and 1st-grade children. An analysis on the type of errors during retrieval indicated that children were more successful at retrieving the correct PCSs than the designated location of those symbols on fixed communication displays. CONCLUSIONS: AAC practitioners should consider using direct selection over scanning whenever possible and account for anticipatory monitoring and pulses when scanning is used in the service delivery of children with little or no functional speech. Also, researchers should continue to investigate AAC selection techniques in relationship to working memory resources.

Analysis of Variance↗
PubMed1987

Symbolic play and social participation abilities of language-impaired and normally developing children.

The symbolic play and social participation behaviors of 6 language-impaired and 8 normal language-learning children were compared on three measures of play: (a) the Symbolic Play Test (Lowe & Costello, 1976), (b) the Brown-Lunzer Scale (Brown, Redmond, Bass, Liebergott, & Swope, 1975), and (c) the Scale of Social Participation in Play (Tizard, Philps, & Plewis, 1976). Subject groups were equated for MLU (Brown, 1973), Developmental Sentence Scoring (Lee, 1974), and performance on the Test of Auditory Comprehension of Language (Carrow, 1973). Results indicated that the language-impaired subjects demonstrated significant deficits in symbolic, adaptive, and integrative play behaviors in comparison with the linguistically equivalent normal subjects. The language-impaired group also evidenced significantly more nonplay and significantly less solitary and parallel play than their normal peers. Findings are discussed with respect to the developmental relationship between language and cognition.

Child↗
PubMed1990

The comparative translucency of initial lexical items represented in five graphic symbol systems and sets.

The comparative translucency within and across five aided augmentative and alternative symbol systems or sets (Blissymbols, Picsyms, PIC, PCS, and Rebus) for symbols representing three parts of speech (nouns, verbs, and modifiers) was investigated. A sample of 41 items representing an initial lexicon was rated by undergraduate college students on a 7-point scale of iconicity. Results indicate that translucency varies among systems or sets and among parts of speech. Rebus and PCS were the most translucent overall; however, a number of Blissymbolics, Picsyms, and PIC symbols were also rated as highly translucent. Caution is indicated in extrapolating results to young or retarded learners because of the influence of normal adult knowledge and experience on translucency ratings. Care must also be taken in extrapolating to more advanced lexicons containing larger, more developmentally advanced vocabularies.

Adult↗
PubMed1993

Induction of a visual symbolic rule in children with specific language impairment.

In a design modeled after that of Connell and Stone (1992), two alternative instructional conditions (Modeling and Imitation) were used to teach a novel morpheme to a group of 21 children with Specific Language Impairment (SLI) (ages 5:0 to 6:11) and to 25 age- and ability-matched peers and 21 language-matched younger peers. In contrast to the use of the auditory modality in the Connell and Stone study, in the present study, the morphemes were embodied in a visual symbol system. The objects and meanings conveyed by the symbols were identical to those used in the earlier study. The present results indicated that both the children with SLI and their age-matched peers showed a benefit to their morpheme production from the requirement to imitate the use of the morpheme during learning trials. These results were interpreted as indicating that the group-specific benefit from imitation instruction on the part of the children with SLI found by Connell and Stone with their auditory task is unique to morpheme learning in the auditory modality. As in the earlier study, the children with SLI also tended to learn less than their age-matched peers in all conditions, indicating a possible general deficiency with symbolic rule induction.

Child↗
PubMed2004

Symbolic reachable set computation of piecewise affine hybrid automata and its application to biological modelling: Delta-Notch protein signalling.

Hybrid automata are an eminently suitable modelling framework for biological protein regulatory networks, as the protein concentration dynamics inside each biological cell are modelled using linear differential equations; inputs activate or deactivate these continuous dynamics through discrete switches, which themselves are controlled by protein concentrations reaching given thresholds. This paper proposes an iterative refinement algorithm for computing discrete abstractions of a class of hybrid automata with piecewise affine continuous dynamics and forced discrete transitions, defined completely in terms of symbolic variables and parameters. Furthermore, these discrete abstractions are utilised to compute symbolic parametric backward reachable sets from the equilibria of the hybrid automata, that are guaranteed to be exact or conservative under-approximations. The algorithm is then implemented using MATLAB and QEPCAD, to compute reachable sets for the biologically observed equilibria of the multiple cell Delta-Notch protein signalling automaton with symbolic parameters. The results are analysed to show that novel, non-intuitive, and biologically interesting properties can be deduced from the reachability computation, thus demonstrating the utility of the algorithm.

Algorithms↗
PubMed2003

Numerical and experimental investigation of the effect of filtering on chaotic symbolic dynamics.

Motivated by the practical consideration of the measurement of chaotic signals in experiments or the transmission of these signals through a physical medium, we investigate the effect of filtering on chaotic symbolic dynamics. We focus on the linear, time-invariant filters that are used frequently in many applications, and on the two quantities characterizing chaotic symbolic dynamics: topological entropy and bit-error rate. Theoretical consideration suggests that the topological entropy is invariant under filtering. Since computation of this entropy requires that the generating partition for defining the symbolic dynamics be known, in practical situations the computed entropy may change as a filtering parameter is changed. We find, through numerical computations and experiments with a chaotic electronic circuit, that with reasonable care the computed or measured entropy values can be preserved for a wide range of the filtering parameter.

Entropy↗
PubMed2004

On the control of chaotic systems via symbolic time series analysis.

Symbolic analysis of time series is extended to systems with inputs, in order to obtain input/output symbolic models to be used for control policy design. For that, the notion of symbolic word is broadened to possibly include past input values. Then, a model is derived in the form of a controlled Markov chain, i.e., transition probabilities are conditioned on the control value. The quality of alternative models with different word length and alphabet size is assessed by means of an indicator based on Shannon entropy. A control problem is formulated, with the goal of confining the system output in a smaller domain with respect to that of the uncontrolled case. Solving this problem (by means of a suitable numerical method) yields the relevant control policy, as well as an estimate of the probability distribution of the output of the controlled system. Three examples of application (based on the analysis of time series synthetically generated by the logistic map, the Lorenz system, and an epidemiological model) are presented and used to discuss the features and limitations of the method.

Journal Article↗
PubMed2003

Traffic sign symbol comprehension: a cross-cultural study.

The objective of this study was to evaluate the comprehension levels of highway traffic sign symbols used in different countries, to identify underlying rules that affect comprehension levels, and recommend approaches to deal with the problem. The need for such an evaluation was based on today's travel culture where people are often licensed in one country and then drive--without any further training--in another country. We compared the comprehension levels of different traffic sign symbols in four countries with moderate to high levels of motorization: Canada, Finland, Israel, and Poland. Five different driver populations were sampled in each country: novice drivers, college students, tourists, problem drivers, and older drivers. There were large differences in comprehension among specific sign messages, different countries, and different driver populations. Signs were comprehended best when they were consistent with general ergonomic guidelines for display design as they relate to spatial compatibility, conceptual compatibility, physical representation, familiarity, and standardization. Illustrations of compliance with these principles and violations of these principles are presented, and their implication for traffic safety are discussed. Specific recommendations for sign design that is compliant with ergonomic principles, and for greater international cooperation in sign symbol design are made.

Accidents, Traffic↗
PubMed1976

Age differences in learning and memory on a digit-symbol substitution task.

Fifteen young (18 to 28 years) and fifteen old (65 to 75 years) persons were given ten 30-second trials on a modified Digit-Symbol task. Both immediate and delayed (24-hour) recall and recognition measures were used to determine how well they remembered the digit-symbol pairs. Both age groups showed similar, significantly improvement over the 10 trials, although the performance level of the young group was higher throughout. The young group showed significantly higher recall and recognition (both immediate and delayed) for the digit-symbol pairs and were more likely to report the use of mnemonic techniques in learning the pairs.

Adolescent↗
PubMedDate not supplied

Age-related slowing on the Digit Symbol task: longitudinal and cross-sectional analyses.

It is generally known that slowing on tasks like the Digit Symbol Substitution task occurs with age. However, simultaneous cross-sectional and longitudinal data are rare. The results from the cross-sectional analysis of Digit Symbol performance with age are compared to results from two occasion longitudinal analyses on the same task. The longitudinal data were obtained from 79 participants who were retested after 7 years and were between the ages of 48 and 73 years old at Time 1. Results indicated that the pattern of actual change observed in the longitudinal analyses replicated the simulated change indicated in the cross-sectional analysis. Antecedents were examined using the original cross-sectional sample of 150 participants. Significant relationships with Digit Symbol performance were found for age, education, and gender, but not for ratings of physical health.

Aged↗
PubMedDate not supplied

Magnitude comparisons by children with specific language impairments: evidence of unimpaired symbolic processing.

A size judgement task was used to investigate number processing skills in children with specific language impairments (SLI). Previous work with unimpaired adults and children has shown that when comparing the size of written numbers and other ordinal stimuli, there is a symbolic distance effect (SDE) such that decision time decreases with the size distance between items. This study examined the ability of children to judge stimulus pairs which were varied to contrast the processing of symbolic material against direct perceptual judgement and to test processing of numeric versus non-numeric material. Children with SLI were compared with a control group matched on verbal comprehension level. The children with SLI responded faster than the control subjects. The SLI and control groups showed similar SDE and a similar pattern of response across materials. No indication was found in the SLI data of any selective deficit in processing symbolic information. Findings are discussed in relation to theories of numeracy acquisition which acknowledge the importance of non-verbal representation of number meanings.

Child↗
PubMed1987

Symbolic reinterpretation of HLA gene products--impact on interpretation of HLA data at the molecular level.

In the HLA system genes are defined by antibody/antigen reactions and are denoted by single symbolic identifiers. This symbolization assumes a one-to-one correspondence between antibodies, antigens and genes. It is important, however, to label each reagent with symbols corresponding to all genes coding for antigens with which the reagent will react. The problems of cross-reactive groups and unexplained linkage relations may be elucidated by the redefinition and clarification of certain HLA antigens. A computer program can suggest such labelling schemes using input given by phenotype reaction patterns with a panel of reagents. When this program was applied to data on the class I HLA antigens a genetic model was suggested that differs somewhat from the currently accepted view. The new model is consistent with applicable and available family data on recombinants and has implications for the interpretation of data at the DNA level.

Chromosome Mapping↗
PubMed1981

Improved digit symbol substitution by older women as a result of extended practice.

Older women (mean = 69 yr) and younger women (mean = 23 yr) received 100 administrations of the Digit Symbol Substitution subtest of the Wechsler Adult Intelligence Scale, modified so that the digit-symbol keys differed on each of the five training days. The older women improved substantially both within and between training sessions, but equally large gains wee made by the younger women so that age differences were not reduced by training. As a consequence of practice, scores of the older women on the standard WAIS subtest increased from the 25th to the 90th percentile relative to norms for young adults, and these scores maintained during a follow-up test 10 days later. Although practice effects transferred to digit-symbol keys different from the training keys, improvements did not generalize to WAIS Digit Span performance or to a matching task containing some of the elements of the training task.

Adolescent↗
PubMed1992

What do adult age differences in the Digit Symbol Substitution Test reflect?

Results from three studies are reported in which adults between 18 and 84 years of age performed various versions of the Digit Symbol Substitution Test. The first study revealed that the age-related declines in digit-symbol performance were largely independent of both the amount of education the participants had received and their self-reported health status, and were characterized by a gradual shift in the entire distribution of scores with little age-related increase in variance. The age relations were greatly attenuated after statistical control of a composite measure of perceptual comparison speed, however, implying considerable commonalities between perceptual comparison speed and what the Digit Symbol Substitution Test measures. Two further studies indicated that young and old adults appeared to use similar strategies to perform the task, and were nearly equivalent in the proportions of time devoted to writing the responses and searching the code table.

Adult↗
PubMed2000

Symbolic approach for measuring temporal "irreversibility"

We describe a symbolic approach for measuring temporal "irreversibility" in time-series measurements. Temporal irreversibility is important because it excludes Gaussian linear dynamics and static transformations of such dynamics from the set of possible generating processes. A symbolic method for measuring temporal irreversibility is attractive because it is computationally efficient, robust to noise, and simplifies statistical analysis of confidence limits. We propose a specific algorithm, called "false flipped symbols," for establishing the presence of temporal irreversibility without the need for generating surrogate data. Besides characterizing experimental data, our results are relevant to the question of selecting alternative models. We illustrate our points with numerical model output and experimental measurements.

Journal Article↗
PubMed2002

Synchronizing the information content of a chaotic map and flow via symbolic dynamics.

In this paper we report an extension to the concept of generalized synchronization for coupling different types of chaotic systems, including maps and flows. This broader viewpoint takes disparate systems to be synchronized if their information content is equivalent. We use symbolic dynamics to quantize the information produced by each system and compare the symbol sequences to establish synchronization. A general architecture is presented for drive-response coupling that detects symbols produced by a chaotic drive oscillator and encodes them in a response system using the methods of chaos control. We include experimental results demonstrating synchronization of information content in an electronic oscillator circuit driven by a logistic map.

Journal Article↗
PubMed2003

Estimating topological entropy via a symbolic data compression technique.

We estimate topological entropy via symbolic dynamics using a data compression technique called the context-tree weighting method. Unlike other symbolic dynamical approaches, which often have to choose ad hoc parameters such as the depth of a tree, the context-tree weighting method is almost parameter-free and infers the transition structure of the system as well as transition probabilities. Our examples, including a Markov model, the logistic map, and the Hénon map, demonstrate that the convergence is fast: one obtains the theoretically correct topological entropy with a relatively short symbolic sequence.

Journal Article↗