RESUMO
Purpose: Letter sequence recognition accuracy has been postulated to be limited primarily by low-level visual factors. The influence of high level factors such as visual memory (load and decay) has been largely overlooked. This study provides insight into the role of these factors by investigating the interaction between letter sequence recognition accuracy, letter string length and report condition. Methods: Letter sequence recognition accuracy for trigrams and pentagrams were measured in 10 adult subjects for two report conditions. In the complete report condition subjects reported all 3 or all 5 letters comprising trigrams and pentagrams, respectively. In the partial report condition, subjects reported only a single letter in the trigram or pentagram. Letters were presented for 100 ms and rendered in high contrast, using black lowercase Courier font that subtended 0.4◦ at the fixation distance of 0.57 m. Results: Letter sequence recognition accuracy was consistently higher for trigrams compared to pentagrams especially for letter positions away from fixation. While partial report increased recognition accuracy in both string length conditions, the effect was larger for pentagrams, and most evident for the final letter positions within trigrams and pentagrams. The effect of partial report on recognition accuracy for the final letter positions increased as eccentricity increased away from fixation, and was independent of the inner/outer position of a letter. Conclusions: Higher-level visual memory functions (memory load and decay) play a role in letter sequence recognition accuracy. There is also suggestion of additional delays imposed on memory encoding by crowded letter elements (AU)
Objetivo: Se ha postulado que la precisión del reconocimiento de la secuencia de letras se ve limitada por los factores visuales de bajo nivel. La influencia de los factores de alto nivel, tales como la memoria visual (carga y deterioro) se ha ignorado en muchas ocasiones. Este estudio aporta mayor información sobre la función de dichos factores, al investigar la interacción entre la precisión del reconocimiento de la secuencia de letras, la longitud de la cadena de letras, y la condición reportada. Métodos: Se midió la precisión del reconocimiento de la secuencia de letras para trigramas y pentagramas en 10 sujetos adultos, para dos condiciones de reporte. En la condición de reporte completa, los sujetos reportaron las 3 ó 5 letras incluidas en los trigramas y pentagramas, respectivamente. En la condición de reporte parcial, los sujetos reportaron únicamente una letra del trigrama o pentagrama. Las letras se presentaron durante 100 milisegundos en alto contraste, con fuente y letra minúscula Courier, subtendiendo 0,4 grados a una distancia de fijación de 0,57 m. Resultados: La precisión del reconocimiento de la secuencia de letras fue consistentemente superior en los trigramas, en comparación a los pentagramas, y en especial para las posiciones de las letras alejadas de la fijación. A pesar de que el reporte parcial incrementó la precisión del reconocimiento en ambas situaciones de longitud de la cadena, el efecto fue superior en los pentagramas, y más evidente para las posiciones de la letra final de los trigramas y pentagramas. El efecto del reporte parcial en la precisión del reconocimiento para las posiciones de la letra final se incrementó a medida que se incrementó la excentricidad alejándose de la fijación, siendo independiente de la posición interna/externa de una letra. Conclusiones: Las funciones de la memoria visual de mayor nivel (carga y deterioro de memoria) juegan una función en la precisión del reconocimiento de la secuencia de letras. Esto sugiere también unas demoras adicionales impuestas sobre la codificación de la memoria, por parte de los elementos del amontonamiento de letras (AU)
Assuntos
Humanos , Adulto , Reconhecimento Visual de Modelos/fisiologia , Reconhecimento Fisiológico de Modelo/fisiologia , Optometria/métodos , Fixação Ocular/fisiologia , Fixação Ocular/efeitos da radiação , Memória de Curto Prazo/fisiologia , Análise de Variância , Leitura , Reconhecimento Fisiológico de Modelo/efeitos da radiação , Psicofísica/métodos , Reconhecimento Visual de Modelos/efeitos da radiaçãoRESUMO
PURPOSE: Letter sequence recognition accuracy has been postulated to be limited primarily by low-level visual factors. The influence of high level factors such as visual memory (load and decay) has been largely overlooked. This study provides insight into the role of these factors by investigating the interaction between letter sequence recognition accuracy, letter string length and report condition. METHODS: Letter sequence recognition accuracy for trigrams and pentagrams were measured in 10 adult subjects for two report conditions. In the complete report condition subjects reported all 3 or all 5 letters comprising trigrams and pentagrams, respectively. In the partial report condition, subjects reported only a single letter in the trigram or pentagram. Letters were presented for 100ms and rendered in high contrast, using black lowercase Courier font that subtended 0.4° at the fixation distance of 0.57m. RESULTS: Letter sequence recognition accuracy was consistently higher for trigrams compared to pentagrams especially for letter positions away from fixation. While partial report increased recognition accuracy in both string length conditions, the effect was larger for pentagrams, and most evident for the final letter positions within trigrams and pentagrams. The effect of partial report on recognition accuracy for the final letter positions increased as eccentricity increased away from fixation, and was independent of the inner/outer position of a letter. CONCLUSIONS: Higher-level visual memory functions (memory load and decay) play a role in letter sequence recognition accuracy. There is also suggestion of additional delays imposed on memory encoding by crowded letter elements.
