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Proactive interference (PI) occurs when an earlier item interferes with memory for a newer item. Whereas some researchers (e.g., Surprenant & Neath, 2009a) argue that PI can be observed in all memory systems, some multiple systems theorists (e.g., Cowan, 1999) propose that items in the focus of attention of working memory are immune to Pl. Two experiments tested whether PI occurs when the to-be-remembered items are assumed, by multiple-systems theorists, to be held in the focus of attention. In each experiment, subjects saw tour trials in a row with the same type of to-be-remembered items, followed by four trials in a row with a different type of material. On each trial, only 3 stimuli were shown, which is below the capacity limit of the focus of attention, and subjects were asked if a probe item was one of those 3 items seen. In both experiments, response time increased from Trial 1 to Trial 4, suggesting that items from the earlier trials interfered with memory on the later trials. In addition, release from PI was shown in that response times decreased with a change of materials. The results replicate those first reported by Hanley and Scheirer (1975), and pose a problem for theorists who argue that parts of short-term memory are immune to PI. Keywords: focus of attention, working memory, proactive interference DOI: 10.1037/a0021011

The authors examined recognition memory for words or visuospatial patterns under full (FA) or divided attention (DA) conditions with a distracting task requiring either phonological (rhyme) or visuospatial (curved-line) processing of letters, in 72 young adults. The authors found an interaction such that the curved-line distracting task had a more detrimental effect on corrected recognition, and discriminability measured by d', for spatial patterns than did the rhyme distracting task, whereas the reverse was true for memory of words. There was also a general effect of DA on response bias such that C increased under DA relative to FA conditions, regardless of the distracting task, and type of information being remembered. Results suggest memory interference from DA at retrieval is process-specific, and that DA at retrieval leads to a more conservative response strategy. Keywords: memory, spatial, verbal, divided attention, retrieval

The acoustic confusion effect is the finding that lists of to-be-remembered items that sound similar to one another are recalled worse than otherwise comparable lists of items that sound different. Previous work has shown that concurrent irrelevant speech and concurrent irrelevant tapping both reduce the size of this effect, suggesting similarities between the two manipulations. The authors assessed the relation between irrelevant speech and irrelevant tapping by correlating the disruption each causes to recall of similar- and dissimilar-sounding items. A significant correlation was obtained, indicating a relation between the two. The results indicate that researchers should be sensitive to changes in the magnitude of the effects rather than focusing exclusively on the presence or absence of particular effects. Implications for the 3 major explanations of the irrelevant speech effect are discussed. Keywords: immediate memory, serial recall, tapping task, interference L'effet de confusion acoustique refere au fait que les listes d'items retenir dont la sonorite entre les items est semblable sont plus difficilement rappelees que des listes equivalentes dont la sonorite entre les items est differente. Des travaux anterieurs ont demontre que le discours concurrent non pertinent et le tapage concurrent non pertinent reduisent la taille de cet effet, suggerant des similitudes entre les deux manipulations. Nous avons evalue la relation entre le discours non pertinent et le tapage non pertinent en correlant l'intefference que chacune des manipulations cause au rappel d'items a sonorite similaire et non similaire. Une correlation significative a ete obtenue, indiquant une relation entre les deux. Les resultats indiquent que les chercheurs devraient etre attentifs la magnitude des effets plutot que de s'interesser exclusivement la presence ou a l'absence d'effets. Une discussion quant aux implications de cette recherche pour les trois explications principales de l'effet du discours non pertinent est presentee. Mots-cles : memoire immediate, rappel seriel, tache de tapping, intefference

Do number-fact retrieval (4 [multiplied by] 6 = ?) and numeral reading (e.g., transcoding 46 into 'forty six') access the same retrieval structures? Data from the present experiment suggest that they do. Under instructions to respond quickly, adults performed simple multiplication problems oriented horizontally or vertically with operands presented simultaneously or with a 500 ms preview of one operand. Errors involving congruent operand intrusions (e.g., 2 [multiplied by] 8 = 24 or 9 [multiplied by] 6 = 36) were most frequent when conditions afforded the left-to-right encoding sequence that is standard for reading multi-digit numbers. Ninety percent of such intrusions involved the correct answer to another simple multiplication problem (e.g., 4 [multiplied by] 8 = 28) rather than a miscellaneous answer (e.g., 4 [multiplied by] 8 = 38). This high rate of arithmetically related intrusions suggests that numeral reading and verbal production of number facts involve a shared representational system.

Using multiplication facts, this experiment demonstrated an interference effect in the number-matching task. Here, subjects verified the presence of a target number (e.g., 8) in a previously presented cue (e.g., 5 x 8) that was masked after 60 ms. The SOAs between cue and target were 100, 120, 220, and 350 ms. Subjects were slower to reject targets that were the product of the cue (e.g., 40) than to reject unrelated targets (e.g., 42), but this was true only at the 100- and 120-ms SOAs (i.e., the interference effect). This pattern is consistent with the interference effect found by LeFevre and colleagues using addition facts. Furthermore, the present result supports the interpretation that the interference effect previously found with addition facts was due to obligatory activation and not to automatic counting.

This experiment examines the interference between tapping and searching in short-term memory (STM). In a concurrent processing condition, the subject first memorized a set of digits, and then executed a series of 17 taps separated by 2 s subjective time intervals. In each intertap interval, a probe was presented for comparison with the items in the memory set. The amount of processing in STM was varied from series to series by manipulating the number of items in the memory set. The results showed that mean duration and variability of intertap intervals increased proportionally with memory set size. This effect is explained by interference between processing in STM and the timing component of the tapping performance. Tapping sensitivity to memory load suggests that, under some conditions, variations in tapping performance are valid indicators of STM processing requirements of a concurrent primary task.

Effects on two bases for recognition-memory judgements were examined using a process dissociation procedure (Jacoby, 1991). In three experiments it was found that increasing the length of a study list interfered with conscious recollection but left familiarity in place. Furthermore, an examination of reaction time distributions as results from a response-signal procedure showed that familiarity was faster as a basis for recognition judgements than was conscious recollection. However, both bases contributed to performance on the fastest as well as the slowest responses, suggesting that the two processes were acting in parallel.

This experiment tests a prediction of a model of priming proposed by McLeod and Walley (1989) in which interference is caused by inhibitory processes between nodes in semantic memory. This model predicts that interference normally found in a high cue validity condition at long SOAS will be considerably increased when a brief target is masked. This prediction was confirmed.

In a spatial version of the Stroop task where subjects must attend to the position of a word and ignore the word itself, we argue that interference results because selective attention is only partially successful. If so, then increasing attention to the word should increase interference. Experiment 1 showed increased interference with position naming when subjects must be prepared to attend to either the word or its position. Experiment 2 required subjects to first name the position of the word and then later to recall which word had been presented. This resulted in increased interference with position naming when the word was followed at a short SOA by a pattern mask. Experiment 3 employed both word reading and position naming and showed that a large reverse Stroop effect occurred with both vocal and manual responses when subjects had to be prepared to attend to either dimension of the stimulus.

Using all four combinations of hand and foot, adult stutterers and nonstutterers performed a unimanual sequential finger tapping task together with a stimulus-contingent foot responding task. The two groups were similar in that both demonstrated more dual-task interference when using the ipsilateral than contralateral limb pairs. Contrary to a prediction based on a hypothesis that attributes stuttering to neural interference due to an ungated or unregulated activity flow between the hemispheres, stutterers did not show more interference than nonstutterers when using the contralateral limb pairs. The groups did differ, however, in terms of finger tapping interference associated with right- versus left-foot concurrent task responding. Nonstutterers showed more interference when using the left than right foot. This was interpreted in terms of the attentional demands that the foot responding task placed on a system with an inherent left-hemisphere attentional bias. The lack of a reliable difference in stutterers with respect to interference by the two feet is consistent with indications from other research that stutterers have a relatively labile system of hemispheric attention or activation. The results of the study are placed into the context of a general model of the brain mechanisms associated with stuttering. Utilisant toutes les quatre combinaisons pied-main, des sujets adultes begues et non-begues etaient soumis a une tache unimanuelle sequentielle d'oscillation digitale alliee a une tache de reponse pedestre en presence d'un stimulus contingent. Les deux groupes de sujets etaient semblables dans le sens ou ils demontraient plus d'interference de double-tache quand ils utilisaient les paires de membres ipsilateraux que contralateraux. Contrairement a la prediction qui decoulait de l'hypothese selon laquelle le begaiement etait du a une interference neuronale resultant d'un flux d'activite deregle entre les hemispheres cerebraux, les begues ne montraient pas plus d'interference que les non-begues lorsqu'ils utilisaient les paires de membres contralateraux. Ces groupes differaient, cependant, quant a l'interference de l'oscillation digitale associee avec la reponse dans la tache concurrente du pied droit vs gauche. Ce resultat etait interprete en termes des demandes attentionnelles que la tache de reponse pedestre posait a un systeme avec un biasis attentionnel inherent a l'hemisphere gauche. L'absence de difference fiable chez les begues quant a l'interference des deux pieds est consistante avec d'autres resultats demontrant que les begues ont un systeme d'attention ou d'activation hemispherique relativement labile. Les resultats obtenus dans cette etude sont discutes dans le contexte d'un modele general des mecanismes cerebraux associes au begaiement.

This paper investigates visual search in displays in which distractors are spatially grouped. Detection of targets at the border of two regions where distractors are coherent is easier than can be predicted by models that do not take spatial organization into account. Thus, models of visual search need to incorporate effects of spatial organization in addition to bottom-up difference calculations.