Long-lasting semantic interference effects in object naming are not necessarily conceptually mediated

Cumulative semantic interference is blind to morphological complexity and originates at the conceptual level

When naming a sequence of pictures of the same semantic category (e.g., furniture), response latencies systematically increase with each named category member. This cumulative semantic interference effect has become a popular tool to investigate the cognitive architecture of language production. However, not all processes underlying the effect itself are fully understood, including the question where the effect originates from. While some researchers assume the interface of the conceptual and lexical level as its origin, others suggest the conceptual-semantic level. The latter assumption follows from the observation that cumulative effects, namely cumulative facilitation, can also be observed in purely conceptual-semantic tasks. Another unanswered question is whether cumulative interference is affected by the morphological complexity of the experimental targets. In two experiments with the same participants and the same material, we investigated both of these issues. Experiment 1, a continuous picture naming task, investigated whether morphologically complex nouns (e.g., kitchen table) elicit identical levels of cumulative interference to morphologically simple nouns (e.g., table). Our results show this to be the case, indicating that cumulative interference is unaffected by lexical information such as morphological complexity. In Experiment 2, participants classified the same target objects as either man-made or natural. As expected, we observed cumulative facilitation. A separate analysis showed that this facilitation effect can be predicted by the individuals’ effect sizes of cumulative interference, suggesting a strong functional link between the two effects. Our results thus point to a conceptual-semantic origin of cumulative semantic interference.

Is semantic processing impaired near the hands?

In a sentence decision task, Davoli et al. (2010) found that the semantic analysis of sentences differed depending on whether the participants' hands were close to or far from the computer screen. According to the authors, the findings reflected an impoverishment of semantic processing near the hands. In the current study, we examine this explanation by asking whether hand position affects 1) other aspects of sentence processing, such as syntactic analysis, 2) semantic processing at the individual word level, and 3) performance in a picture naming task that requires access to meaning. In Experiment 1, participants judged the acceptability of sentences, half of which included semantic or syntactic violations. In Experiment 2, only semantically acceptable or nonacceptable sentences were presented. In Experiment 3, participants performed a go/nogo semantic categorization task on individual words. In Experiment 4, participants performed a picture naming task. Participants performed these tasks both with their hands near to and far from the computer screen. Regardless of the task, we found no evidence of impoverished semantic processing near the hands.

The influence of semantic associations on sentence production in schizophrenia: an fMRI study

One of the most prominent symptoms of schizophrenia is thought disorder, which manifests itself in language production difficulties. In patients with thought disorders the associations are loosened and sentence production is impaired. The determining behavioral and neural mechanisms of sentence production are still an important subject of recent research and have not yet been fully understood. The aim of the current study was to examine the influence of associative relations and distractor modalities on sentence production in healthy participants and participants with schizophrenia. Therefore, reaction times and neural activation of 12 healthy subjects and 13 subjects with schizophrenia were compared in an adapted picture word interference paradigm (PWI). No significant group differences were found, neither on the behavioral nor on the neural level. On the behavioral level, for the entire group incremental sentence processing was found, i.e. processing of the second noun only starts after the first noun was processed. At the neural level, activation was discovered in the bilateral caudate nuclei and the cerebellum. Those activations could be related to response enhancement and suppression as well as to the modulation of cognitive processes.

Being fast or slow at naming depends on recency of experience

The speed with which we produce words (e.g., dog) changes depending on whether a word named in the past is from the same semantic category (e.g., cat) or not (e.g., vase). Strikingly, whereas earlier studies find that producing semantically related words speeds up subsequent naming, recent studies report that it slows down future naming. It is unclear why the same experience results in opposite effects and whether both effects originate within the language system. Using the same picture naming paradigm and materials, we manipulated the interval between two naming events, while reducing the influence of expectation. We observed facilitation when semantically related pictures were presented adjacently. By contrast, when semantically related pictures were separated by two unrelated pictures, interference was observed. The results suggest that both facilitation and interference effects emerge within the language system where changes are critically based on the interval between naming, rather than solely due to peripheral processes associated with task demands.

When comprehension elicits incomprehension: Deterioration of semantic categorisation in the absence of stimulus repetition

Repetition improves retrieval from memory; however, under some circumstances, it can also impair performance. Separate literatures have investigated this phenomenon, including studies showing subjective loss of meaning following ‘semantic satiation’, slowed naming and categorisation when semantically related items are repeated and semantic ‘access deficits’ in aphasia. Such effects have been variously explained in terms of habituation of repeatedly accessed representations, increased interference from strongly activated competitors and long-term weight changes reflecting the suppression of non-targets on earlier trials (i.e., retrieval-induced forgetting). While studies of semantic satiation involve massed repetition of individual items, competition and weight changes at the conceptual level should elicit declining comprehension for non-repeated items: this pattern has been demonstrated for picture naming but effects in categorisation are less clear. We developed a paced serial semantic task (PSST), in which participants identified category members among distracters. Performance in healthy young adults deteriorated with ongoing retrieval for non-repeated words belonging to functional categories (e.g., picnic), taxonomic categories (e.g., animal) and feature-based categories (e.g., colour red – ‘tomato’, ‘post box’). This decline was greatest at fast presentation speeds (when there was less time to overcome competition/inhibition) and for strongly associated targets (which may have accrued more inhibition to facilitate earlier target categorisation). Deteriorating performance was also seen across words and pictures, consistent with a conceptual locus. We observed a release from deteriorating categorisation following a switch to a new category, demonstrating that this was not a general effect of time on task. Patients with semantic aphasia, who have deficient semantic control, maintained their performance throughout the categories, unlike younger adults: this finding is hard to reconcile with accounts of declining performance that propose a build-up of competition, since the patients should have had greater difficulty resolving such competition. These results instead suggest that declining performance on our goal-driven categorisation task was linked to the use of a controlled retrieval strategy by healthy young adults. Patients may not have inhibited related non-target knowledge to facilitate initial categorisation like younger volunteers, and consequently they were less vulnerable to declining comprehension in this paradigm. Together, these results demonstrate circumstances which produce declines in continuous categorisation in healthy adults.

Semantic interference in speech error production in a randomized continuous naming task: Evidence from aphasia

Naming pictures from the same semantic category hinders subsequent naming from that category (i.e., semantic interference), irrespective of the number of intervening different-category exemplars named. Persistent semantic interference has been well documented in chronometric studies, and has been attributed to experience-driven adjustments in the strength of connections between semantic and lexical representations. However, whether parallel effects exist in speech error data remains unclear. In the current study, people with aphasia, a speaker population prone to naming errors, provided naming responses to a large picture corpus presented in random order that comprised multiple exemplars drawn from several different categories. We found persistent semantic interference in the task in semantic error rates specifically, and that semantic similarity between consecutive related exemplars modulated the effect. The results provide further evidence for the presumed lexical-semantic locus and mechanism(s) underlying semantic interference.

The shape of things to come in speech production: Visual form interference during lexical access

Naming a picture is slower in categorically related compared with unrelated contexts, an effect termed semantic interference. This effect has informed the development of all contemporary models of lexical access in speech production. However, category members typically share visual features, so semantic interference might in part reflect this confound. Surprisingly, little work has addressed this issue, and the relative absence of evidence for visual form interference has been proposed to be problematic for production models implementing competitive lexical selection mechanisms. In a series of five experiments using two different naming paradigms, we demonstrate a reliable visual form interference effect in the absence of a category relation and show the effect is more likely to originate during lexical or later response selection than during perceptual/conceptual processing. We conclude visual form interference in naming is a significant complicating factor for studies of semantic interference effects and discuss the implications for current accounts of lexical access in spoken word production.

Facilitation and interference in naming: A consequence of the same learning process?

Our success with naming depends on what we have named previously, a phenomenon thought to reflect learning processes. Repeatedly producing the same name facilitates language production (i.e., repetition priming), whereas producing semantically related names hinders subsequent performance (i.e., semantic interference). Semantic interference is found whether naming categorically related items once (continuous naming) or multiple times (blocked cyclic naming). A computational model suggests that the same learning mechanism responsible for facilitation in repetition creates semantic interference in categorical naming (Oppenheim, Dell, & Schwartz, 2010). Accordingly, we tested the predictions that variability in semantic interference is correlated across categorical naming tasks and is caused by learning, as measured by two repetition priming tasks (picture-picture repetition priming, Exp. 1; definition-picture repetition priming, Exp. 2, e.g., Wheeldon & Monsell, 1992). In Experiment 1 (77 subjects) semantic interference and repetition priming effects were robust, but the results revealed no relationship between semantic interference effects across contexts. Critically, learning (picture-picture repetition priming) did not predict semantic interference effects in either task. We replicated these results in Experiment 2 (81 subjects), finding no relationship between semantic interference effects across tasks or between semantic interference effects and learning (definition-picture repetition priming). We conclude that the changes underlying facilitatory and interfering effects inherent to lexical access are the result of distinct learning processes where multiple mechanisms contribute to semantic interference in naming.

The Role of Task-Specific Response Strategies in Blocked-Cyclic Naming

In word retrieval, speakers need to select a lexical entry among several co-activated candidates for lexicalization. How a target entry is selected is a matter of ongoing debate. Semantic context effects on naming times, as seen in the blocked-cyclic naming paradigm, are of specific interest to this debate. In the standard version of this paradigm, participants name lists of objects compiled from several repetitions (cycles) of a small set of semantically related objects (homogeneous context) or unrelated objects (heterogeneous context). In the first cycle, participants typically show either no context effect or semantic facilitation. From cycle two onward, they display a stable semantic interference effect that does not increase over cycles. In this review, I demonstrate that the early semantic facilitation effect is only observed consistently in studies that present homogeneous and heterogeneous lists in a blocked fashion. With this design, participants can easily pick up on the categorical relatedness of the items in semantically related contexts and apply this knowledge strategically. In principle, such response strategies can be easily tied in with existing models of lexical selection, but they are incompatible with accounts of semantic context effects that take the semantic facilitation effect in cycle 1 to be a consequence of processes inherent to the lexicalization process. Users of the blocked-cyclic naming paradigm should review their experimental designs carefully regarding potential response strategies. Once these are taken into account, the paradigm can be used to study lexical-semantic encoding in different populations of healthy and also impaired speakers.

Language production in a shared task: Cumulative Semantic Interference from self- and other-produced context words

This study assessed the effects of semantic context in the form of self-produced and other-produced words on subsequent language production. Pairs of participants performed a joint picture naming task, taking turns while naming a continuous series of pictures. In the single-speaker version of this paradigm, naming latencies have been found to increase for successive presentations of exemplars from the same category, a phenomenon known as Cumulative Semantic Interference (CSI). As expected, the joint-naming task showed a within-speaker CSI effect, such that naming latencies increased as a function of the number of category exemplars named previously by the participant (self-produced items). Crucially, we also observed an across-speaker CSI effect, such that naming latencies slowed as a function of the number of category members named by the participant's task partner (other-produced items). The magnitude of the across-speaker CSI effect did not vary as a function of whether or not the listening participant could see the pictures their partner was naming. The observation of across-speaker CSI suggests that the effect originates at the conceptual level of the language system, as proposed by Belke's (2013) Conceptual Accumulation account. Whereas self-produced and other-produced words both resulted in a CSI effect on naming latencies, post-experiment free recall rates were higher for self-produced than other-produced items. Together, these results suggest that both speaking and listening result in implicit learning at the conceptual level of the language system but that these effects are independent of explicit learning as indicated by item recall.