Biomedical subjects

Martha Anne Roberts

Publications and source records attributed to Martha Anne Roberts.

4 recordsLinked to original sources

PubMed2005

Stroop dilution revisited: evidence for domain-specific, limited-capacity processing.

Nine experiments show that in the context of Stroop dilution the extent to which flanking distractors are processed depends on the nature of the material at fixation. A Stroop effect is eliminated if a word or a nonword is colored and appears at fixation and the color word appears as a flanker. A Stroop effect is observed when the color carrier at fixation is from a different domain than the color word distractor (e.g., Arabic digits). It is argued that when the material at fixation is in the same domain as the color word distractor, the distractor is not processed. Taken together, these results implicate a role for material-specific, limited-capacity processing in the context of this variant of the Stroop paradigm.

Attention↗

PubMed2004

Single letter coloring and spatial cuing eliminates a semantic contribution to the Stroop effect.

Previous work has shown that the Stroop effect is reduced in size when a single letter is colored and spatially precued. The present experiment addresses a number of criticisms of this work by (1) providing a direct measure of semantic processing, (2) using a vocal response instead of a manual one, and (3) using a more appropriate baseline. A semantically based Stroop effect (slower color naming for color-associated words than for color-neutral words) is observed when all letters in the display are precued and appear in a homogeneous color. This Stroop effect is statistically eliminated when a single letter is precued and is the "odd man out" in terms of its color. Two explanations are considered. In one, single-letter coloring and cuing serve to curtail semantic processing. In the other, single-letter coloring and cuing help to keep the informational sources (i.e, color, word) separate and hence reduce interference, but semantic analysis is not curtailed. The latter account provides a more complete account of existing data.

Color Perception↗

PubMed2003

Reading nonwords aloud: results requiring change in the dual route cascaded model.

The time to name a nonword increases monotonically as letter length increases. The leading computational model of basic processes in reading (Coltheart, Rastle, Perry, Langdon & Ziegler's dual route cascaded model) simulates this, because its nonlexical route assigns phonemes to letters serially, left to right, and arguably, this corresponds to what humans do. New simulation work shows that (1) this letter length effect interacts with the effect of slowing the rate of early processing, and (2) the model produces a qualitatively different pattern from that observed with university-level readers. The contrast between simulation and human performance thus illuminates a problem with how the nonlexical route operates in the model, and constrains accounts that can be provided for the human data. Consideration is given to thresholding the output of the letter-level module as a way to modify the model so as to make it possible to simulate the human data.

Humans↗

PubMed2003

When parallel processing in visual word recognition is not enough: new evidence from naming.

Low-frequency irregular words are named more slowly and are more error prone than low-frequency regular words (the regularity effect). Rastle and Coltheart (1999) reported that this irregularity cost is modulated by the serial position of the irregular grapheme-phoneme correspondence, such that words with early irregularities exhibit a larger cost than words with late ones. They argued that these data implicate rule-based serial processing, and they also reported a successful simulation with a model that has a rule-based serial component--the DRC model of reading aloud (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001). However, Zorzi (2000) also simulated these data with a model that operates solely in parallel. Furthermore, Kwantes and Mewhort (1999) simulated these data with a serial processing model that has no rules for converting orthography to phonology. The human data reported by Rastle and Coltheart therefore neither require a serial processing account, nor successfully discriminate among a number of computational models of reading aloud. New data are presented wherein an interaction between the effects of regularity and serial position of irregularity is again reported for human readers. The DRC model simulated this interaction; no other implemented computational model does so. The present results are thus consistent with rule-based serial processing in reading aloud.

Humans↗