title: The effect of letter string length and report condition on letter recognition accuracy.
abstract: OBJECTIVE
  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.
authors.affiliation: Michigan College of Optometry, 1124 S State Street, Big Rapids, MI 49341, USA. Electronic address: raghuna@ferris.edu.
authors.forename: Avesh
authors.initials: A
authors.lastname: Raghunandan
authors.affiliation: Michigan College of Optometry, 1124 S State Street, Big Rapids, MI 49341, USA.
authors.forename: Berta
authors.initials: B
authors.lastname: Karmazinaite
authors.affiliation: Michigan College of Optometry, 1124 S State Street, Big Rapids, MI 49341, USA.
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Rossow
mesh_terms: D000328:Adult; D005260:Female; D005364:Field Dependence-Independence; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011932:Reading; D015203:Reproducibility of Results; D012684:Sensory Thresholds / Q000502:physiology*; D014787:Vision Tests / Q000379:methods*; D055815:Young Adult
keywords: Carga de la memoria; Crowding; Crowding (amontonamiento); Letter sequence recognition; Memory load; Pentagramas; Pentagrams; Reconocimiento de la secuencia de letras; Trigramas; Trigrams