Covert orienting: A compound-cue account of the proportion cued effect

An increase in the proportion of spatially cued trials in the context of the covert orienting paradigm increases the magnitude of the cuing effect. This proportion cued effect is widely interpreted to reflect a form of control. Specifically, it is argued that participants strategically allocate attention as a function of the utility of the spatial cue. Here, an alternative explanation of the proportion cued effect is proposed that does not require control. According to this account, the cue-target event forms a compound cue and the proportion cued manipulation produces a relative disparity in the frequency with which particular compound cues occur. Specifically, when the proportion of spatially cued trials is increased, the frequency of spatially cued cue-target events increases and the frequency of spatially miscued cue-target events decreases, thus increasing the magnitude of the cuing effect. The results of two experiments support this account.     

Neighbourhood density, word frequency, and spelling-sound regularity effects in naming: similarities and differences between skilled readers and the Dual Route Cascaded Computational model.

An experiment with skilled readers and a series of simulations with the Dual Route Cascaded model (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001) investigated the joint effects of stimulus quality and Neighbourhood Density (N) in nonword naming. Neighbourhood Density and stimulus quality yielded additive effects on RT for skilled readers whereas the model produced an interaction between these factors. A further set of simulations show that DRC also produces an interaction between stimulus quality and (1) word frequency, (2) spelling-sound regularity, and, (3) nonword letter length. None of these three factors interact with stimulus quality in performance by skilled readers. It is suggested that DRC's assumption of cascaded processing throughout represents a central problem. A proposal as to how the model can be modified to accommodate these and other problematic data is discussed.     

When are morphemic and semantic priming observed in visual word recognition?

J. Stolz and D. Besner (1998) reported a dissociation between morphemic and semantic priming in the context of lexical decision. Morphemic priming was observed following letter search on the prime display, but semantic priming was not. Participants in the present experiment identified the colour of a single letter in the prime display before making a lexical decision to the target. Both morphemic and semantic priming were observed. These results are discussed in relation to the observation that identifying the colour of a single letter of a word in the Stroop task is associated with a reduction in the size of the Stroop effect as compared to when all letters are coloured.     

Mental size scaling examined

Observers made same-different shape judgments of stimuli that were identical in shape and size different in shape but not in size, or differed in relative size along a number of steps for both same- and different- shaped forms. "Same" judgment RTs increased monotonically with increases in the magnitude of the relative size difference. In contrast, "different" judgment RTs were unaffected by changes in relative size. A second experiment in which stimulus presentation was successive rather than simultaneous yielded essentially the same results. Consideration was given to a dual- process model in which a time-consuming analog process normalizes stimuli that are size discrepant prior to a comparison stage that is operative for those structures responsible for "same" decisions but not for "different" judgments. Some evidence that seems inconsistent with a normalization process which operates prior to contact with memory was discussed, and an alternative explanation in which the early detection of a size difference causes changes in decision criteria was suggested.     

Phonological encoding in the lexical decision task

In lexical decision experiments, subjects have difficulty in responding NO to non-words which are pronounced exactly like English words (e.g. BRANE). This does not necessarily imply that access to a lexical entry ever occurs via a phonological recoding of a visually-presented word. The phonological recoding procedure might be so slow that when the letter string presented is a word, access to its lexical entry via a visual representation is always achieved before phonological recoding is completed. If prelexical phonological recodings are produced by using grapheme-phoneme correspondence rules, such recodings can only occur for words which conform to these rules (regular words), since applications of the rules to words which do not conform to the rules (exception words) produce incorrect phonological representations. In two experiments, it was found that time to achieve lexical access (as measured by YES latency in a lexical decision task) was equivalent for regular words and exception words. It was concluded that access to lexical entries in lexical decision experiments of this sort does not proceed by sometimes or always phonologically recoding visually-presented words.     

Is eye gaze direction always determined without intent?

It is widely assumed that processing of gaze direction occurs “automatically,” in the sense that it is reflexive (unfolds in the absence of intention). We assessed this view in a task in which participants saw a schematic face in which the eyes were gazing left or right, along with a second directional target (an arrow in Experiment 1; a directional word in Experiment 2). The eyes and other directional target were sometimes congruent and other times incongruent. On each trial, participants were cued with a tone to respond to either the direction the eyes were gazing, or the direction the noneye target indicated. The time between the onset of the task cue and the onset of the face was manipulated so that on half the trials the face and the cue were presented at the same time. Regardless of the type of target, the congruency effect was the same size at the zero SOA as it was at the 750 SOA, suggesting that eyes were not processed until participants knew what task to perform. These results are consistent with the claim that processing of gaze direction is, at least some of the time, secondary to an intent (i.e., it is not reflexive).     

Contingency learning and unlearning in the blink of an eye: A resource dependent process

Recent studies show that when words are correlated with the colours they are printed in (e.g., MOVE is presented 75% of the time in blue), colour identification is faster when the word is presented in its correlated colour (MOVE in blue) than in an uncorrelated colour (MOVE in green). The present series of experiments explored the possible mechanisms involved in this colour-word contingency learning effect. Experiment 1 demonstrated that the effect is already present after 18 learning trials. During subsequent unlearning, the effect extinguished equally rapidly. Two reanalyses of data from Schmidt, Crump, Cheesman, and Besner (2007) ruled out an account of the effect in terms of stimulus repetitions. Experiment 2 demonstrated that participants who carry a memory load do not show a contingency effect, supporting the hypothesis that limited-capacity resources are required for learning. Experiment 3 demonstrated that memory resources are required for both storage and retrieval processes.     

Word identification: Imageability, semantics, and the content-functor distinction

It has often been suggested that different special-purpose mechanisms underlie the processing of content words and function words. The received view is that processing differences in various tasks arise because of differences between these word classes in terms of their semantic/syntactic function, despite the fact that these tasks often involve word processing in the absence of any sentence context. It is also well known that the ease with which a word arouses a sensory impression is often a good predictor of word-processing performance, yet the literature largely ignores the fact that, typically, imageability and word class are confounded factors. A series of three experiments shows that in the context of a Stroop task, the typical content-function word difference can be obtained, but that this word class difference disappears completely when the items are matched on the dimension of imageability. It is suggested that the processing of decontextualized content and function words does not necessarily engage distinct special purpose processing mechanisms. Implications for understanding previously published work on word class effects in other paradigms are briefly noted.