Distinguishing common and task-specific processes in word identification: a matter of some moment?

The same 500 words were presented in 6 different word identification tasks (Experiment 1: lexical decision, semantic categorization, and 3 speeded naming tasks; Experiment 2: delayed naming). Reaction time (RT) distributions were estimated for each task and analyses tested for the effects of word frequency and animacy on various parameters of the RT distribution. Low frequency words yielded more skewed distributions than high frequency words in all tasks except delayed naming. The differential skew was most marked for tasks that required lexical discrimination. The semantic categorization task yielded highly skewed distributions for all words, but the word frequency effect was due to shifts in the location of the RT distributions rather than changes in skew. The results are used to evaluate the relative contributions of a common lexical access process and task-specific processes to performance in lexical discrimination and naming tasks.     

Why do non-color words interfere with color naming?

In the non-color-word Stroop task, university students' response latencies were longer for low-frequency than for higher frequency target words. Visual identity primes facilitated color naming in groups reading the prime silently or processing it semantically (Experiment 1) but did not when participants generated a rhyme of the prime (Experiment 3). With auditory identity primes, generating an associate or a rhyme of the prime produced interference (Experiments 2 and 3). Color-naming latencies were longer for nonwords than for words (Experiment 4). There was a small long-term repetition benefit in color naming for low-frequency words that had been presented in the lexical decision task (Experiment 5). Facilitation of word recognition speeds color naming except when phonological activation of the base word increases response competition.     

Changes in alertness and processing capacity in a serial learning task

Second-to-second changes in processing capacity were examined using a concurrent task paradigm involving serial learning and simple reaction time (RT) in two experiments. Experiment 1 demonstrated the feasibility of combining probe RT with a slow-paced serial learning task including perceptually isolated items. Experiment 2 employed the same concurrent tasks to compare cardiac interbeat interval (IBI, the reciprocal of heart rate) with probe RT. Second-to-second changes during item processing were found consistently for both measures. However, these changes appeared to be more related to observing and response requirements than to the specific cognitive processes required by the tasks. Correctly anticipated items were associated with (l)RT changes, suggesting heightened allocation of capacity, and (2)a cardiac IBI response of episodic cardiac deceleration imposed upon the task-induced cardiac speeding. The probe RT and cardiac IBI measures showed reasonable convergence in assessing the allocation of processing capacity. The concept of the accessibility of allocated capacity was introduced in considering instances of the divergence of probe RT and cardiac IBI.     

Selective and nonselective inhibition of competitors in picture naming

The present study examined the relation between nonselective inhibition and selective inhibition in picture naming performance. Nonselective inhibition refers to the ability to suppress any unwanted response, whereas selective inhibition refers to the ability to suppress specific competing responses. The degree of competition in picture naming was manipulated by presenting targets along with distractor words that could be semantically related (e.g., a picture of a dog combined with the word cat) or unrelated (tree) to the picture name. The mean naming response time (RT) was longer in the related than in the unrelated condition, reflecting semantic interference. Delta plot analyses showed that participants with small mean semantic interference effects employed selective inhibition more effectively than did participants with larger semantic interference effects. The participants were also tested on the stop-signal task, which taps nonselective inhibition. Their performance on this task was correlated with their mean naming RT but, importantly, not with the selective inhibition indexed by the delta plot analyses and the magnitude of the semantic interference effect. These results indicate that nonselective inhibition ability and selective inhibition of competitors in picture naming are separable to some extent.     

Task choice and semantic interference in picture naming

Evidence from dual-task performance indicates that speakers prefer not to select simultaneous responses in picture naming and another unrelated task, suggesting a response selection bottleneck in naming. In particular, when participants respond to tones with a manual response and name pictures with superimposed semantically related or unrelated distractor words, semantic interference in naming tends to be constant across stimulus onset asynchronies (SOAs) between the tone stimulus and the picture–word stimulus. In the present study, we examine whether semantic interference in picture naming depends on SOA in case of a task choice (naming the picture vs reading the word of a picture–word stimulus) based on tones. This situation requires concurrent processing of the tone stimulus and the picture–word stimulus, but not a manual response to the tones. On each trial, participants either named a picture or read aloud a word depending on the pitch of a tone, which was presented simultaneously with picture–word onset or 350 ms or 1000 ms before picture–word onset. Semantic interference was present with tone pre-exposure, but absent when tone and picture-word stimulus were presented simultaneously. Against the background of the available studies, these results support an account according to which speakers tend to avoid concurrent response selection, but can engage in other types of concurrent processing, such as task choices.     

Word production deficits in schizophrenia

Fronto-cerebellar circuitry is implicated in word production. Data suggest that the cerebellum is involved in word search, whereas the prefrontal cortex underlies the selection of words from among competing alternatives. We explored the role of search and selection processes in word production deficits in schizophrenia patients. In Experiment 1, patients were impaired in a verb generation task under both high and low selection conditions but were more impaired in the high selection condition. In Experiment 2, when the difficulty level of search and selection conditions was equated in a word stem completion task, patients were only impaired in the search condition. Word search deficits underlie word production problems in schizophrenia, and may involve fronto-cerebellar dysfunction.     

Semantic component of a cross-modal Stroop-like task

Three experiments showed that the pattern of interference of single-modality Stroop tests also exists cross-modally. Distractors and targets were either pictures or auditory words. In a naming task (Experiment 1), word distractors from the same semantic category as picture targets interfered with picture naming more than did semantically unrelated distractors; the semantic category of picture distractors did not differentially affect word naming. In a categorization task (Experiment 2), this Stroop-like effect was reversed: Picture distractors from the same semantic category as word targets interfered less with word categorization than picture distractors that were semantically unrelated; the semantic category of word distractors did not differentially affect picture categorization. Experiment 3 replicated these effects when each subject performed both tasks; the task, naming or categorizing, determined the pattern of interference between pictures and auditory words. The results thus support the existence of a semantic component of a cross-modal Stroop-like effect.     

Distractor strength and selective attention in picture-naming performance

Whereas it has long been assumed that competition plays a role in lexical selection in word production (e.g., Levelt, Roelofs, & Meyer, 1999), recently Finkbeiner and Caramazza (2006) argued against the competition assumption on the basis of their observation that visible distractors yield semantic interference in picture naming, whereas masked distractors yield semantic facilitation. We examined an alternative account of these findings that preserves the competition assumption. According to this account, the interference and facilitation effects of distractor words reflect whether or not distractors are strong enough to exceed a threshold for entering the competition process. We report two experiments in which distractor strength was manipulated by means of coactivation and visibility. Naming performance was assessed in terms of mean response time (RT) and RT distributions. In Experiment 1, with low coactivation, semantic facilitation was obtained from clearly visible distractors, whereas poorly visible distractors yielded no semantic effect. In Experiment 2, with high coactivation, semantic interference was obtained from both clearly and poorly visible distractors. These findings support the competition threshold account of the polarity of semantic effects in naming.     

The cumulative semantic cost does not reflect lexical selection by competition

The cumulative semantic cost describes a phenomenon in which picture naming latencies increase monotonically with each additional within-category item that is named in a sequence of pictures. Here we test whether the cumulative semantic cost requires the assumption of lexical selection by competition. In Experiment 1 participants named a sequence of pictures, while in Experiment 2 participants named words instead of pictures, preceded by a gender marked determiner. We replicate the basic cumulative semantic cost with pictures (Exp. 1) and show that there is no cumulative semantic cost for word targets (Exp. 2). This pattern was replicated in Experiment 3 in which pictures and words were named along with their gender marked definite determiner, and were intermingled within the same experimental design. In addition, Experiment 3 showed that while picture naming induces a cumulative semantic cost for subsequently named words, word naming does not induce a cumulative semantic cost for subsequently named pictures. These findings suggest that the cumulative semantic cost arises prior to lexical selection and that the effect arises due to incremental changes to the connection weights between semantic and lexical representations.     

The influence of spelling on phonological encoding in word reading, object naming, and word generation

Does the spelling of a word mandatorily constrain spoken word production, or does it do so only when spelling is relevant for the production task at hand? Damian and Bowers (2003) reported spelling effects in spoken word production in English using a prompt-response word generation task. Preparation of the response words was disrupted when the responses shared initial phonemes that differed in spelling, suggesting that spelling constrains speech production mandatorily. The present experiments, conducted in Dutch, tested for spelling effects using word production tasks in which spelling was clearly relevant (oral reading in Experiment 1) or irrelevant (object naming and word generation in Experiments 2 and 3, respectively). Response preparation was disrupted by spelling inconsistency only with the word reading, suggesting that the spelling of a word constrains spoken word production in Dutch only when it is relevant for the word production task at hand.     

Word familiarity and frequency in visual and auditory word recognition

Four experiments investigate printed word frequency and subjective rated familiarity. Words of varied printed frequency and subjective familiarity were presented. A reaction time advantage for high-familiarity and high-frequency words was found in visual (Experiment 1) and auditory (Experiment 2) lexical decision. In Experiments 3 and 4, a cued naming task elicited a naming response after a specified delay after presentation. In Experiment 3, naming of visual words showed a frequency effect with no naming delay. The frequency effect diminished at longer delay intervals. Naming times for auditorily presented words (Experiment 4) showed no frequency effect at any delay. Both naming experiments showed familiarity effects. The relevance of these results are discussed in terms of the role of printed frequency for theories of lexical access, task- and modality-specific effects, and the nature of subjective familiarity.     

Selective attention and priming: Inhibitory and facilitatory effects of ignored primes

The priming effects of ignored information have been studied in Stroop displays (Neill, 1977) and with spatially superimposed drawings (Tipper, in this issue); naming of probes related to ignored primes is delayed in these experiments (“negative priming”). This negative priming effect is confirmed in a list reading task in Experiment 1, which used partially superimposed letters, and Experiment 2, which used spatially separated letters. Furthermore, Lowe (1979) using Stroop colour words observed that changing the nature of the probe such that it did not require selection from a competing word reversed the priming effects of the ignored word from inhibition to facilitation. Experiment 3 confirmed this observation when subjects selected a red letter from a green letter. Two models are suggested to account for this result. In the first, negative priming is a product of the ignored prime and subsequent probe being encoded both as a stimulus to be ignored and one to be named (Allport, Tipper and Chmiel, in press; Lowe, in press). This dual encoding is ambiguous, requiring further processing before response can be output. The other model suggests that negative priming reflects inhibition of response to ignored information, slowing naming latencies to probe stimuli that require the same response. Experiment 4 attempts to differentiate between the models, and the latter inhibition view is preferred.     

Attention, temporal predictability, and the time course of context effects in naming performance

Models of attention and context effects in naming performance should be able to account for the time course of color-word Stroop interference revealed by manipulations of the stimulus onset asynchrony (SOA) between color and word. Prominent models of Stroop task performance ( [Cohen et al., 1990], [Cohen and Huston, 1994] and [Phaf et al., 1990]) fail to account for the fact that response time (RT) and Stroop interference peak at zero SOA and diminish with word preexposure. The models may be saved by assuming that the time course of interference is determined by a strategic orienting of attention to color onsets when SOA is predictable. To test this temporal predictability hypothesis, SOA was blocked or randomly mixed in Experiment 1. In addition, the time interval between color onsets was randomly variable in Experiment 2. Although RTs were affected, none of the randomization manipulations influenced the typical shape of the time course of Stroop effects. These findings provide evidence against the temporal predictability hypothesis and thereby against prominent models of the Stroop task.     

Individual differences in word recognition latency

Previous studies of the effects of word characteristics on word recognition have used orthogonal combinations of word variables and have failed to consider individual differences. The present study examined word naming (Experiment 1) and lexical decision (Experiment 2) tasks using an unrestricted set of words and a correlational analysis. Individual differences were considered using a measure of the subjects’ knowledge of the English vocabulary. The results of Experiment 1 indicated that log (RT) for word naming is affected by word length, word frequency, and the number of syllables in the word; the results of Experiment 2 confirmed the effects of length and frequency but also showed that log (RT) is a function of the age at which the word is introduced to a child’s reading vocabulary. Subjects with a high vocabulary score were more rapid in Experiment 1 but were slower in Experiment 2, compared to subjects with a low vocabulary score. More importantly, high-vocabulary subjects, in both studies, were less affected by word length than the low-vocabulary subjects. The results suggest that subjects do differ in their reading strategy and that word length and word frequency may affect different stages in the word recognition process.     

Influence of imaging ability on word transformation

In the present study, we examined whether individual differences in imaging ability affect visual word recognition. Poor and vivid imagers performed a naming task that involved nonreversed (e.g., JUMP) and reversed (e.g., PMUJ) words (Experiment 1). Poor and vivid imagers were also tested on a naming task that was controlled for verbal ability; all the words were reversed and presentation time was varied (Experiment 2). In both experiments, imaging ability interacted with task difficulty, suggesting that individual differences in imaging ability affect visual word recognition. Specifically, the present data suggest that poor imagers may be less efficient than vivid imagers at processing words analytically. The data are interpreted within a limited-capacity, hybrid, word recognition model, in which words can be processed as either word-level or letter-level codes.     

Capacity demands of phoneme selection in word production: new evidence from dual-task experiments

Three dual-task experiments investigated the capacity demands of phoneme selection in picture naming. On each trial, participants named a target picture (Task 1) and carried out a tone discrimination task (Task 2). To vary the time required for phoneme selection, the authors combined the targets with phonologically related or unrelated distractor pictures (Experiment 1) or words, which were clearly visible (Experiment 2) or masked (Experiment 3). When pictures or masked words were presented, the tone discrimination and picture naming latencies were shorter in the related condition than in the unrelated condition, which indicates that phoneme selection requires central processing capacity. However, when the distractor words were clearly visible, the facilitatory effect was confined to the picture naming latencies. This pattern arose because the visible related distractor words facilitated phoneme selection but slowed down speech monitoring processes that had to be completed before the response to the tone could be selected.     

Identity primes produce facilitation in a colour naming task

Five experiments examined associative or identity priming effects in a colour-naming task with colour-neutral words. In Experiment 1, subjects instructed to read the prime silently showed no associative priming effect but a colour-naming facilitation with identity priming. In Experiment 2, the typical associative priming interference in colour naming was demonstrated in subjects recalling the prime word, but not in subjects reading the prime silently, whereas associative primes facilitated word naming regardless of the prime response requirement. The remaining studies investigated the colour-naming facilitation observed with identity primes. Experiment 3 showed no effects on the facilitation of colour naming from varying the letter case of a silently read prime. Experiment 4 showed facilitation when subjects recalled the prime, and a target frequency effect, with faster colour-naming latencies for high- and medium- than low-frequency targets. In Experiment 5, there was no facilitation for naming the colour of target words paired with non-word primes differing in their initial letter from the target. Taken together, the results suggest that the facilitation of colour naming following identical primes reflects faster target word recognition, whereas the associative priming interference reflects an attentional effect.     

Top-down inhibition of search distractors in parallel visual search

In three experiments, we examined distractor inhibition in parallel ("pop-out") visual search. Distractor inhibition was measured in terms of reaction time (RT) to a simple luminance increment probe presented, after the search task response, at display locations that either contained a search distractor (on-probe) or were blank (off-probe). When the search stimuli remained in view, the on-probe (relative to off-probe) RT cost was larger than in a baseline condition in which observers had only to passively view, rather than search, the display. This differential on-probe RT cost, which discounts effects of masking, was interpreted as a measure of distractor inhibition associated with target selection in parallel visual search. Taken together, the results argue that the distractor inhibition is an object-based and local phenomenon that affects all distractors (of a particular type) in an equal manner.     

Sex and coding strategy effects on reaction time to hemispheric probes

Two experiments were conducted to investigate the influence of coding instructions on cerebral laterality differences. Experiment I required 20 subjects (10 female) to use either rehearsal or imagery coding strategies in a recognition task with word probes to the right and left hemispheres. No hemispheric differences were found, but sex of subject was found to be related to coding strategy. Ten subjects (5 female) in Experiment II performed a similar task, except picture probes were used. Subjects using rehearsal coding responded faster to left-hemisphere probes, but faster to right-hemisphere probes when imagery coding was employed. The differing laterality effects in these experiments were attributed to naming responses implicitly required in Experiment II.     

On the nonautomaticity of visual word processing: electrophysiological evidence that word processing requires central attention

The present study used event-related potentials (ERPs) to determine the degree to which people can process words while devoting central attention to another task. Experiments 1-4 measured the N400 effect, which is sensitive to the degree of mismatch between a word and the current semantic context. Experiment 5 measured the P3 difference between low- and high-frequency words. Because these effects can occur only if a word has been identified, both ERP components index word processing. The authors found that the N400 effect (Experiments 1, 3, and 4) and the P3 difference (Experiment 5) were strongly attenuated for Task 2 words presented nearly simultaneously with Task 1. No such attenuation was found when the Task 1 stimulus was presented but required no response (Experiment 2). Strong attenuation was also evident when the Task 2 word was presented before the Task 1 stimulus (Experiment 4), suggesting that central resources are not allocated to stimuli first-come, first-served but rather are strategically locked to Task 1. The authors conclude that visual word processing is not fully automatic but rather requires access to limited central attentional resources.