Visual processing of nonlinguistic strings: redundancy effects and reading ability.

Visual redundancy effects were investigated in two experiments using nonalphabetic material. Experiment 1 had adult subjects search for the presence or absence of a predetermined target symbol through single six-symbol linear arrays. Reaction times were significantly faster in both a distributional redundancy and a spatial redundancy condition than in a no-redundancy condition. Experiment 2 had good and poor sixth-grade readers serve in the no-redundancy and spatial redundancy conditions of Experment 1. Poor readers were equivalent to good readers in the no-redundancy condition but were significantly slower in the spatial redundancy condition. Thus, spatial redundancy was shown to be operative in single symbol search time in a paradigm that avoided confounding by higher order linguistic variables. The present experiments, in conjunction with prior findings that good and poor readers differ in letter search time by their ability to use spatial redundancy, suggest that processes involved in the component skill of letter identification cannot be considered trivial to the reading process.