Detection errors in a task with articulatory suppression: Phonological receding and reading

In two experiments, subjects read passages of text and circled instances of a target letter under normal conditions or while engaged in articulatory suppression. In Experiment 1, subjects searching for the letter e made a disproportionately large number of errors on the word “the” and more errors when e occurred in unstressed than in stressed syllables of three-syllable words. In Experiment 2, subjects searching for the letter f made an exceedingly large number of errors on the word “of.” Articulatory suppression significantly reduced the stress effect in the three-syllable words but did not reduce the tendency to make errors on “the” or “of,” suggesting that phonological recoding is responsible for this effect of stress but does not influence the unitization processes of reading.     

Phonology, lexical access in reading, and articulatory suppression: A critical review

Considerable confusion exists in the literature on visual word recognition and reading with respect to the effects of articulatory suppression upon phonological recoding. The authors of a large number of journal articles, chapters, cognitive psychology textbooks, and books devoted to reading processes have concluded that suppression interferes with phonological receding of print and have used this supposed fact as a basis for determining when phonology is involved in various reading tasks. Others have concluded that suppression need not interfere with phonological recoding (e.g. Besner, Davies and Daniels, 1981; Besner and Davelaar, 1982). The present review concludes that a phonological code can be derived from printed English and used for lexical access without interference from suppression. However, operations performed upon a phonological code—e.g. post-assembly phonemic segmentation and deletion, maintenance in working memory—are disrupted by suppression. A review of the literature supports this distinction; some implications of these views are noted.     

The effect of articulatory suppression and manual tapping on serial recall

Concurrent tasks, such as articulatory suppression and manual tapping, are used to understand the mechanisms underlying short-term memory by overloading domain-specific resources. The present study addresses the debate regarding the theoretical frameworks accounting for interference in serial recall by comparing the effects of both the modality of concurrent tasks (verbal vs. spatial) as well as the state of the tasks (steady vs. changing) in both verbal and spatial recall. The findings indicate that the verbal changing-state concurrent task significantly impaired digit recall, whereas the spatial changing-state concurrent task significantly impaired block recall. The theoretical implications are discussed in the context of a multimodal working memory model with domain-specific resources and a unitary approach to short-term memory.     

The role of articulatory suppression in immediate false recognition

False memory for critical lures has been widely documented in long-term memory using the Deese/Roediger-McDermott paradigm. Recent evidence suggests that false memory effects can also be found in short-term memory (STM), supporting models that assume a strong relationship between short-term and long-term memory processes. However, no study has examined the role of articulatory suppression on immediate false memory, even though phono-articulatory factors are critically involved in STM performance and are an intrinsic part of all STM accounts. The current study proposes a novel paradigm to assess false memory effects in a STM task under both silent and articulatory suppression conditions. Using immediate serial recognition, in which participants had to judge whether two successive mixed lists of six associated and non-associated words were matched, we examined true recognition of matching lists and false recognition of mismatching lists comprising a critical lure or unrelated distractor in two experiments. Results from both experiments indicated reduced true recognition of matching lists and greater false serial recognition of mismatching lists comprising a critical lure under articulatory suppression relative to silence. These findings provide further support for some current models of verbal short-term memory, which posit a strong relationship between short-term and long-term memory processes.     

The role of articulatory suppression in immediate false recognition

False memory for critical lures has been widely documented in long-term memory using the Deese/Roediger-McDermott paradigm. Recent evidence suggests that false memory effects can also be found in short-term memory (STM), supporting models that assume a strong relationship between short-term and long-term memory processes. However, no study has examined the role of articulatory suppression on immediate false memory, even though phono-articulatory factors are critically involved in STM performance and are an intrinsic part of all STM accounts. The current study proposes a novel paradigm to assess false memory effects in a STM task under both silent and articulatory suppression conditions. Using immediate serial recognition, in which participants had to judge whether two successive mixed lists of six associated and non-associated words were matched, we examined true recognition of matching lists and false recognition of mismatching lists comprising a critical lure or unrelated distractor in two experiments. Results from both experiments indicated reduced true recognition of matching lists and greater false serial recognition of mismatching lists comprising a critical lure under articulatory suppression relative to silence. These findings provide further support for some current models of verbal short-term memory, which posit a strong relationship between short-term and long-term memory processes.     

Manipulations of irrelevant information: Suffix effects with articulatory suppression and irrelevant speech

Numerous studies have demonstrated impaired recall when the to-be-remembered information is accompanied or followed by irrelevant information. However, no current theory of immediate memory explains all three common methods of manipulating irrelevant information: requiring concurrent articulation, presenting irrelevant speech, and adding a stimulus suffix. Five experiments combined these manipulations to determine how they interact and which theoretical framework most accurately and completely accounts for the data. In Experiments 1 and 2, a list of auditory items was followed by an irrelevant speech sound (the suffix) while subjects engaged in articulatory suppression. Although articulatory suppression reduced overall recall compared to a control condition, comparable suffix effects were seen in both conditions. Experiments 3 and 4 found reliable suffix effects when list presentation was accompanied by irrelevant speech. Experiment 5 found a suffix effect even when the irrelevant speech was composed of a set of different items. Implications for working memory, pre-categorical acoustic store, the changing-state hypothesis, and the feature model are discussed.     

Word frequency,articulatory suppression and memory span

Watkins (1977) found memory span was longer when first and second halves of lists contained high- and low-frequency words, respectively, than when low-frequency words preceded high. One of the four experiments reported here failed to replicate this finding and found that articulatory suppression had a greater detrimental effect on span for high- than for low-frequency words. Another experiment showed that high-frequency words similar to those used by Watkins were easier to articulate than low-frequency words. In the third experiment articulatory suppression did not differentially affect delayed recall of high- and low-frequency words. The fourth experiment showed span for high- and low-frequency words was influenced in a similar way when encouraging subjects to maintain words from either early or late serial positions by articulatory rehearsal. It is concluded that differences in the strategies adopted to maintain words in the articulatory rehearsal loop can account for inconsistencies in the results obtained here and in previous experiments.     

Mirror reading of words and numbers: Practice and transfer effects

It remains unknown whether mirror reading represents a genuine text processing skill or is based on recognition of visual patterns. The present study attempts to determine whether (1) systematic practice with a particular mirrored typography also improves reading performance for other mirrored typographies, and whether (2) this transfer extends from lexical to numerical material and vice versa. The results show that short-term intensive practice with mirror-reversed words significantly improves reading performance not only for the trained typography but also for other mirrored typographies and mirror-reversed Arabic digits. Practice with mirror-reversed Arabic digits showed a mixed pattern of transfer effects with regard to other digit transformations and there were no transfer effects to lexical material. Hence, for lexical material, at least, improvement after training seems to be based on generalized skill with transfer effects beyond lexical material, rather than on mere improvement of visual recognition of the material used in training.     

Effects of response-stimulus interval manipulation and articulatory suppression on task switching

We conducted three experiments using a list paradigm to examine how articulatory suppression and response-stimulus interval (RSI) manipulation affected task switching. Experiments 1 and 2 tested task-switching performance under a short and long RSI and three concurrent task conditions (control, articulatory suppression, and tapping) without external task cues. The results indicated that alternation had a greater effect under articulatory suppression than under the control and tapping conditions, and that articulatory suppression costs were unrelated to the RSI. In Experiment 3, an external task cue was provided with each stimulus, and the negative effect of articulatory suppression on alternation cost was eliminated. These results indicated that articulatory suppression effects did not differ between conditions of short and long RSI and that the availability of verbal representations of task information was independent of RSI length. This paper discussed the possible roles played by the phonological loop in task-switching paradigms.     

The suppression of visualization by reading

Four experiments are described which demonstrate a conflict between reading verbal messages and imagining the spatial relations described by those messages. Listening to the same messages did not produce comparable interference with visualization. The conflict between reading and visualizing was obtained even when the subject previously had seen the referent of the message. In contrast, when the subject was induced to treat the messages as rote strings of words instead of visualizing their referents, reading was a more effective means of presentation than was listening.

Two interpretations of these results were proposed. (a) Visualization and reading compete of the use of neural pathways specialized for visual perception. (b) The process of reading hinders the conversion of input material into any non-verabl form; that is, reading forces the subject to deal with information in a more exclusively verbal form than does listening. It was suggested that regardless of interpretation this method provides a means of investigating the internal processes underlying concrete verbal reference.     

The effect of articulatory suppression on implicit and explicit false memory in the DRM paradigm

Several studies have shown that reliable implicit false memory can be obtained in the DRM paradigm. There has been considerable debate, however, about whether or not conscious activation of critical lures during study is a necessary condition for this. Recent findings have revealed that articulatory suppression prevents subsequent false priming in an anagram task (Lovden & Johansson, 2003). The present experiment sought to replicate and extend these findings to an implicit word stem completion task, and to additionally investigate the effect of articulatory suppression on explicit false memory. Results showed an inhibitory effect of articulatory suppression on veridical memory, as well as on implicit false memory, whereas the level of explicit false memory was heightened. This suggests that articulatory suppression did not merely eliminate conscious lure activation, but had a more general capacity-delimiting effect. The drop in veridical memory can be attributed to diminished encoding of item-specific information. Superficial encoding also limited the spreading of semantic activation during study, which inhibited later false priming. In addition, the lack of item-specific and phenomenological details caused impaired source monitoring at test, resulting in heightened explicit false memory.     

Impairment of rhyme judgments by silent and overt articulatory suppression

Two experiments showed that articulating “blah” repeatedly aloud or silently interfered with the speed and accuracy of judging whether pairs of words rhymed. Articulation from another voice affected only accuracy, and foot tapping had no effect. This suggests that it is mainly the articulatory component of articulatory suppression that interferes with this task and that rhyme judgments of words depend on an articulatory code or an acoustic code accessed via articulation.

A third experiment confirmed these effects on speed of judgment, but there were no significant effects on errors in this experiment. Non-verbal use of the articulatory musculature in chewing also slowed performance. Similar results were obtained for word and non-word rhyme judgments, though the latter effects were somewhat weaker. It is argued that the results fail to support the theory that there are different methods of accessing phonology for words or non-words and indicate that access to phonology was via articulation, rather than a means to achieving articulation. If the task incorporated mechanisms employed in normal reading, the results refute suggestions that conversion of print to sound, whether for words or non-words, occurs prior to retrieval of an articulatory code.     

Differential effects of articulatory suppression on cue-switch and task-switch trials in random task cueing with 2:1 mapping

Recent studies have revealed that verbal representations play an important role in various task-switching situations. This study examined whether verbal representations contribute to the actual switching process using random task cueing with two cues per task. This procedure allowed us to produce a trial in which the cue switched, but the task repeated, thereby separating the cue-switching process from the actual task-switching process. Participants performed colour or shape judgements that were initiated by an arbitrary symbol cue (Experiments 1 and 2) or a kanji cue (Experiment 3) under control, articulatory-suppression, and foot-tapping conditions. In Experiments 1 and 2 with the arbitrary cues, articulatory suppression impaired performance in only the cue-switch condition. In Experiment 3, in which a kanji cue indicated the upcoming task name, articulatory suppression did not have any effects. These results suggest that the involvement of verbal representations in random task cueing is based on the cue-switching process rather than on the task-switching process.     

Differential effects of articulatory suppression on cue-switch and task-switch trials in random task cueing with 2:1 mapping

Recent studies have revealed that verbal representations play an important role in various task-switching situations. This study examined whether verbal representations contribute to the actual switching process using random task cueing with two cues per task. This procedure allowed us to produce a trial in which the cue switched, but the task repeated, thereby separating the cue-switching process from the actual task-switching process. Participants performed colour or shape judgements that were initiated by an arbitrary symbol cue (Experiments 1 and 2) or a kanji cue (Experiment 3) under control, articulatory-suppression, and foot-tapping conditions. In Experiments 1 and 2 with the arbitrary cues, articulatory suppression impaired performance in only the cue-switch condition. In Experiment 3, in which a kanji cue indicated the upcoming task name, articulatory suppression did not have any effects. These results suggest that the involvement of verbal representations in random task cueing is based on the cue-switching process rather than on the task-switching process.     

Phonological encoding and ideographic reading by the disconnected right hemisphere: Two case studies

The mute disconnected right hemispheres (RHs) of two commissurotomy patients are able to understand spoken words and read printed words by matching them with pictures of the objects named. In this paper we report the results of five experiments. The RH of one patient could “evoke the sound image” of a word to the extent of matching two pictures with homonymous names (experiment 1) or with rhyming names (experiment 2) without being able to name either one. This transformation of picture to covert sound does not depend on orthographic similarity of word ends as a clue to homonymy or rhyme, nor does it improve with short-term learning. Yet neither RH can translate print into sound by matching a spelled word with a picture that has a rhyming name (experiment 3) or by matching two orthographically dissimilar rhymes, be they meaningful (experiment 4) or nonsense words (experiment 5). We suggest that these RHs read “ideographically,” recognizing words directly as visual gestalts without intermediate phonetic recoding or grapheme-to-phoneme translation.     

Directly assessing the relationship between irrelevant speech and articulatory suppression

Larsen and Baddeley (2003) examine whether the disruption caused by articulatory suppression on immediate memory tasks is similar to or different from the disruption caused by irrelevant speech. Based on experiments in which they test whether the phonological similarity effect is present or absent, they conclude that articulatory suppression and irrelevant speech are different. We assessed whether articulatory suppression and irrelevant speech are similar or different by correlating the disruption each causes. A significant correlation obtained, indicating a relation between the two. These apparently different conclusions can be readily resolved by adopting the view that articulatory suppression, irrelevant speech, and many other factors vary in the degree to which they are likely to cause subjects to abandon reliance on phonological/acoustic cues in particular tasks.     

Word length and articulatory suppression affect short-term and long-term recall tasks

In six experiments, subjects were required to recall (either serially or freely) lists of short and long words either immediately or after a study-test filled delay ranging from 30 to 60 sec. In three of these experiments, we investigated the effect that articulatory suppression had in modulating the word length effect in both immediate and delayed free recall. The results suggested that the effects of word length and articulatory suppression were comparable in the immediate and delayed recall tasks. The theoretical relevance of these findings is discussed.