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.     

Enhanced phonological facilitation and traces of concurrent word form activation in speech production: An object-naming study with multiple distractors

In the present study, we extended the classic picture–word interference paradigm by the presentation of multiple distractor words (Experiment 1) to reexamine whether the word forms of semantic alternatives receive activation in the course of object naming. Experiment 2 showed that phonological facilitation can be magnified by the presentation of multiple words that share overlapping initial and final segments with the target name. Experiments 3 and 4 tested for traces of nontarget phonological activation with multiple distractors, which enhances the chances of detecting such effects. These experiments revealed a consistent pattern of interference effects induced by words that were related to a semantic category member, consistent with theories assuming phonological activation of nontarget alternatives.     

The inability to ignore auditory distractors as a function of visual task perceptual load

Using a response competition paradigm, we investigated the ability to ignore target response-compatible, target response-incompatible, and neutral visual and auditory distractors presented during a visual search task. The perceptual load model of attention (e.g., Lavie & Tsal, 1994) states that task-relevant processing load determines irrelevant distractor processing in such a way that increasing processing load prevents distractor processing. In three experiments, participants searched sets of one (easy search) or six (hard search) similar items. In Experiment 1, visual distractors influenced reaction time (RT) and accuracy only for easy searches, following the perceptual load model. Surprisingly, auditory distractors yielded larger distractor compatibility effects (median RT for incompatible trials minus median RT for compatible trials) for hard searches than for easy searches. In Experiments 2 and 3, during hard searches, consistent RT benefits with response-compatible and RT costs with response-incompatible auditory distractors occurred only for hard searches. We suggest that auditory distractors are processed regardless of visual perceptual load but that the ability to inhibit cross-modal influence from auditory distractors is reduced under high visual load.     

Rhythmic movement is attracted more strongly to auditory than to visual rhythms

People often move in synchrony with auditory rhythms (e.g., music), whereas synchronization of movement with purely visual rhythms is rare. In two experiments, this apparent attraction of movement to auditory rhythms was investigated by requiring participants to tap their index finger in synchrony with an isochronous auditory (tone) or visual (flashing light) target sequence while a distractor sequence was presented in the other modality at one of various phase relationships. The obtained asynchronies and their variability showed that auditory distractors strongly attracted participants' taps, whereas visual distractors had much weaker effects, if any. This asymmetry held regardless of the spatial congruence or relative salience of the stimuli in the two modalities. When different irregular timing patterns were imposed on target and distractor sequences, participants' taps tended to track the timing pattern of auditory distractor sequences when they were approximately in phase with visual target sequences, but not the reverse. These results confirm that rhythmic movement is more strongly attracted to auditory than to visual rhythms. To the extent that this is an innate proclivity, it may have been an important factor in the evolution of music.     

On the categorical nature of the semantic interference effect in the picture-word interference paradigm

Two picture-word interference experiments are reported in which the boundaries of the semantic interference effect are explored. In both experiments, participants named pictures (e.g., a picture of a car) that appeared with superimposed word distractors. Distractor words from the same semantic category as the word for the picture (e.g., CAR) produced semantic interference, whereas semantically related distractors from a different category (e.g.,Bumper) led to semantic facilitation. In Experiment 2, the semantic facilitation from semantically related distractors was replicated. These results indicate that a semantic relationship between picture and distractor does not necessarily lead to interference and in fact can lead to facilitation. In all but one case tested until now, a semantic relationship between picture and distractor has led to semantic facilitation. The implications of these results for the assumption that the semantic interference effect arises as a consequence of lexical competition are discussed.     

Semantic and phonological information flow in the production lexicon

When speakers produce words, lexical access proceeds through semantic and phonological levels of processing. If phonological processing begins based on partial semantic information, processing is cascaded; otherwise, it is discrete. In standard models of lexical access, semantically processed words exert phonological effects only if processing is cascaded. In 3 experiments, speakers named pictures of objects with homophone names (ball), while auditory distractor words were heard beginning 150 ms prior to picture onset. Distractors speeded picture naming (compared with controls) only when related to the nondepicted meaning of the picture (e.g., dance), exhibiting an early phonological effect, thereby supporting the cascaded prediction. Distractors slowed picture naming when categorically (e.g., frisbee) related to the depicted picture meaning, but not when associatively (e.g., game) related to it. An interactive activation model is presented.     

Processing segmental and prosodic information in Cantonese word production

Five experiments were conducted to investigate how subsyllabic, syllabic, and prosodic information is processed in Cantonese monosyllabic word production. A picture-word interference task was used in which a target picture and a distractor word were presented simultaneously or sequentially. In the first 3 experiments with visually presented distractors, null effects on naming latencies were found when the distractor and the picture name shared the onset, the rhyme, the tone, or both the onset and tone. However, significant facilitation effects were obtained when the target and the distractor shared the rhyme + tone (Experiment 2), the segmental syllable (Experiment 3), or the syllable + tone (Experiment 3). Similar results were found in Experiments 4 and 5 with spoken rather than visual distractors. Moreover, a significant facilitation effect was observed in the rhyme-related condition in Experiment 5, and this effect was not affected by the degree of phonological overlap between the target and the distractor. These results are interpreted in an interactive model, which allows feedback sending from the subsyllabic to the lexical level during the phonological encoding stage in Cantonese word production.     

Asymmetric aging effects on semantic and phonological processes: naming in the picture-word interference task

In 2 experiments, participants named pictures while ignoring auditory word distractors. For pictures with homophone names (e.g., ball), distractors semantically related to the nondepicted meaning (e.g., prom) facilitated naming by top-down phonological connections for young but not for older adults. Slowing from unrelated distractors and facilitation from phonologically related distractors were age invariant except in distractors that were both semantically and phonologically related. Only distractors semantically related to the picture interfered more for older than younger adults. These results ar einconsistent with age-linked deficits in inhibition of irrelevant information from either internal or external sources. Rather, aging affects priming transmission in a connectionist network with asymmetric effects on semantic and phonological connections involved in comprehension and production, respectively.     

Assessing the role of orthography in speech perception and production: Evidence from picture–word interference tasks

The effects of orthographic and phonological relatedness between distractor word and object name in a picture–word interference task were investigated. In Experiment 1 distractors were presented visually, and consistent with previous findings, priming effects arising from phonological overlap were modulated by the presence or absence of orthographic similarity between distractor and picture name. This pattern is interpreted as providing evidence for cascaded processing in visual word recognition. In Experiment 2 distractors were presented auditorily, and here priming was not affected by orthographic match or mismatch. These findings provide no evidence for orthographic effects in speech perception and production, contrary to a number of previous reports.     

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.     

Distinct,but top-down modulable color and positional priming mechanisms in visual pop-out search

Three experiments examined reaction time (RT) performance in visual pop-out search. Search displays comprised of one color target and two distractors which were presented at 24 possible locations on a circular ellipse. Experiment 1 showed that re-presentation of the target at a previous target location led to expedited RTs, whereas presentation of the target at a distractor location led to slowed RTs (relative to target presentation at a previous empty location). RTs were also faster when the color of the target was the same across consecutive trials, relative to a change of the target’s color. This color priming was independent of the positional priming. Experiment 2 revealed larger positional facilitation, relative to Experiment 1, when position repetitions occurred more likely than chance level; analogously, Experiment 3 revealed stronger color priming effects when target color repetitions were more likely. These position and color manipulations did not change the pattern of color (Experiment 2) and positional priming effects (Experiment 3). While these results support the independency of color and positional priming effects (e.g., Maljkovic and Nakayama in Percept Psychophys 58:977–991, 1996), they also show that these (largely ‘automatic’) effects are top-down modulable when target position and color are predictable (e.g., Müller et al. in Vis Cogn 11:577–602, 2004).     

Locus of semantic interference in picture-word interference tasks

Picture#x2014;word interference studies typically show that semantically related distractor words embedded within a picture slow picture-naming responses, relative to unrelated ones. This semantic interference effect is commonly interpreted as arising from the competition of lexical#x2014;semantic (e.g., Schriefers, Meyer, & Levelt, 1990) or lexical#x2014;phonological (e.g., Starreveld & La Heij, 1996) codes. The experiment reported here tests a crucial assumption shared by these accounts#x2014;namely, that the effect reflects a lexical, rather than a nonverbal, conceptual conflict. Pictures were named while participants attempted to ignore embedded distractors that were in either verbal or pictorial format. The presence of both words and pictures substantially interfered with naming responses, but only words, not pictures, were found to induce semantic interference. These findings support the claim that for semantic interference to arise, both target picture and distractor have to be lexicalized. Consequently, a general conceptual locus of the effect can be excluded, and the claim that semantic interference is based on a lexical conflict is confirmed.     

Semantic competition between hierarchically related words during speech planning

There is overwhelming evidence that during speech planning semantically related words become lexically activated and compete for selection with the to-be-produced target word. The vast majority of this evidence stems from studies using the picture-word task, in which a distractor word (e.g., bird) drawn from the same semantic category as the target (e.g., fish) was shown to inhibit the picture-naming response more strongly than did an unrelated distractor word. By contrast, corresponding evidence from distractor words (e.g., carp) bearing a hierarchical relation to the target (e.g., fish) is sparse and inconclusive. In the present study, we investigated effects of subordinate-level distractors during basic-level naming and effects of basic-level distractors during subordinate-level naming. Hierarchically related distractors were found to inhibit the naming response in both situations. This pattern of results did not depend on whether the pictures were preferably named at the basic level or at the subordinate level. The results suggest that hierarchically related name alternatives compete for selection.     

Activating Semantic Knowledge During Spoken Words and Environmental Sounds: Evidence From the Visual World Paradigm

Two visual world experiments investigated the activation of semantically related concepts during the processing of environmental sounds and spoken words. Participants heard environmental sounds such as barking or spoken words such as “puppy” while viewing visual arrays with objects such as a bone (semantically related competitor) and candle (unrelated distractor). In Experiment 1, a puppy (target) was also included in the visual array; in Experiment 2, it was not. During both types of auditory stimuli, competitors were fixated significantly more than distractors, supporting the coactivation of semantically related concepts in both cases; comparisons of the two types of auditory stimuli also revealed significantly larger effects with environmental sounds than spoken words. We discuss implications of these results for theories of semantic knowledge.     

The activation of word class information during speech production

In 5 picture-word interference experiments the activation of word class information was investigated. The first experiment, in which subjects used bare nouns to describe the pictures, failed to reveal any interference effect of noun distractor words as opposed to closed-class distractor words. In the next 4 experiments the pictures were named by using a definite determiner and the noun completing a sentence fragment. The data demonstrate that noun distractors interfere more strongly with picture naming than do non-noun distractors. This held for both visual and auditory presentation of the distractor words. The interference effect showed up in a time window where semantic interference can usually be observed, supporting the assumption that at an early stage of lexical access semantic and syntactic activation processes overlap.     

Comparing color-word and picture-word Stroop-like effects: A test of the Glaser and Glaser (1989) model

Summary Glaser and Glaser (1989) assume that the processing of colors and pictures is highly similar in that, compared to words, both kinds of stimulis have privileged access to semantic information. This assumption was tested in the present research. In Experiment 1, the season corresponding to the color or to the word of color-word Stroop stimuli had to be named (e.g., green for spring). In Experiment 2, subjects had to name the season corresponding to the picture or the word of a picture-word stimulus (e. g., flower for spring). According to Glaser and Glaser (1989), privileged semantic processing of colors and pictures should be evidenced by a larger interfering power of color and picture distractors than of word distractors. However, the asymmetric pattern of interference was observed only with picture-word stimuli (Experiment 2), but not with color-word stimuli (Experiment 1), suggesting that, unlike pictures, colors do not have privileged access to semantic information. It was also found that word distractors interfered with the semantic processing of pictures, a result that is incompatible with the dominance rule postulated by Glaser and Glaser (1989). From these results, an adapted version of the Glaser and Glaser model is proposed: colors are assumed to have privileged access to a separate color processing system and the pattern of interference depends upon the relative activation strength of the response alternatives activated by the target and the distractor.     

Resolving competition when naming an object in a multiple-object display

Naming an object in the context of other objects requires the selection and processing of the target object at different levels, while the processing of competing representations activated by context objects has to be constrained. At what stage are these competing representations attenuated? To address this question, we presented pairs of target and context objects that were either similar in visual shape (e.g., umbrella–palm tree) or dissimilar in visual shape (e.g., umbrella–ladder), so that the context object would attract various amounts of attention. The activation of the context object at different levels of processing was assessed by means of auditory distractors (semantically related, or phonologically related, or unrelated to the context object). Semantic and phonological distractor effects were observed for shape-related object pairs, but not for unrelated object pairs. This finding suggests that context objects do not activate their associated lexical representations to any substantial amount, unless they capture attention. In that case, they undergo full lexical processing up to a phonological level. Implications for models of word production are discussed.     

The role of phonological and visual working memory in complex arithmetic for Chinese- and Canadian-educated adults

Two experiments were conducted to test cultural differences in the role of phonological and visual working memory in complex arithmetic. Canadian- and Chinese-educated students solved complex subtraction problems (e.g., 85 − 27; Experiment 1) and complex multiplication problems (e.g., 6 − 13; Experiment 2) under phonological and visual working memory loads. Problem complexity (i.e., borrow or carry operations) and presentation format (i.e., horizontal vs. vertical) were also manipulated. The results showed that both Chinese- and Canadian-educated participants relied on both phonological and visual working memory resources when solving complex subtraction and multiplication problems. Selective involvement of phonological and visual working memory as a function of operation (Lee & Kang, 2002) or presentation format (Trbovich & LeFev re, 2003) was found only for Chinese-educated participants and not for Canadian-educated participants, calling into question the generalizability of these findings across arithmetic operations and cultural groups.     

Auditory context effects in picture naming investigated with event-related fMRI

Naming an object entails a number of processing stages, including retrieval of a target lexical concept and encoding of its phonological word form. We investigated these stages using the picture-word interference task in an fMRI experiment. Participants named target pictures in the presence of auditorily presented semantically related, phonologically related, or unrelated distractor words or in isolation. We observed BOLD signal changes in left-hemisphere regions associated with lexical-conceptual and phonological processing, including the midto-posterior lateral temporal cortex. However, these BOLD responses manifested as signal reductions for all distractor conditions relative to naming alone. Compared with unrelated words, phonologically related distractors showed further signal reductions, whereas only the pars orbitalis of the left inferior frontal cortex showed a selective reduction in response in the semantic condition. We interpret these findings as indicating that the word forms of lexical competitors are phonologically encoded and that competition during lexical selection is reduced by phonologically related distractors. Since the extended nature of auditory presentation requires a large portion of a word to be presented before its meaning is accessed, we attribute the BOLD signal reductions observed for semantically related and unrelated words to lateral inhibition mechanisms engaged after target name selection has occurred, as has been proposed in some production models.     

Semantic priming is affected by real-time phonological competition: Evidence for continuous cascading systems

Lexical-semantic access is affected by the phonological structure of the lexicon. What is less clear is whether such effects are the result of continuous activation between lexical form and semantic processing or whether they arise from a more modular system in which the timing of accessing lexical form determines the timing of semantic activation. This study examined this issue using the visual world paradigm by investigating the time course of semantic priming as a function of the number of phonological competitors. Critical trials consisted of high or low density auditory targets (e.g., horse) and a visual display containing a target, a semantically related object (e.g., saddle), and two phonologically and semantically unrelated objects (e.g., chimney, bikini). Results showed greater magnitude of priming for semantically related objects of low than of high density words, and no differences for high and low density word targets in the time course of looks to the word semantically related to the target. This pattern of results is consistent with models of cascading activation, which predict that lexical activation has continuous effects on the level of semantic activation, with no delays in the onset of semantic activation for phonologically competing words.