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The present study investigated the ability to inhibit the processing of an irrelevant visual object while processing a relevant one. Participants were presented with 2 overlapping shapes (e.g., circle and square) in different colors. The task was to name the color of the relevant object designated by shape. Congruent or incongruent color words appeared in the relevant object, in the irrelevant object, or in the background. Stroop effects indicated how strong the respective area of the display was processed. The results of 4 experiments showed that words in the relevant object produced larger Stroop effects than words in the background, indicating amplification of relevant objects. In addition, words in the irrelevant object consistently produced smaller Stroop effects than words in the background, indicating inhibition of irrelevant objects. Control experiments replicated these findings with brief display durations (250 ms) and ruled out perceptual factors as a possible explanation. In summary, results support the notion of an inhibitory mechanism of object-based attention, which can be applied in addition to the amplification of relevant objects. Keywords: facilitation, Stroop effect, object-based attention, inhibition

ABSTRACT. The authors manipulated the extent of distractor interference with learned, mapped responses by presenting distractors to participants (N = 16) before, simultaneously with, or after the target. Interference was [...]

We extend the finding that word reading slows following successful responses to a color-word Stroop interference task (Masson, Bub, Woodward, & Chan, 2003). Word reading was assessed in a picture-word interference task in which subjects alternated between naming a picture (with either a word or a row of Xs superimposed on it) and reading a word. For the word-reading task, words were presented either in isolation or superimposed on a picture. Word reading was slower after subjects responded to a bivalent stimulus that required resolution of conflict (naming a picture with a word superimposed on it) than after they responded to a stimulus that involved no conflict (naming a picture with Xs superimposed on it), indicating modulation of dominant task performance. This effect was found when word-reading targets were superimposed on pictures but not when those targets were presented in isolation. Modulation of word reading, therefore, appears to be the result of interference from a persistent picture-naming task set, cued by a stimulus configuration that invites execution of both competing tasks.

Morrison and colleagues have proposed that auditory hallucinations are the result of cognitive intrusions being misattributed to an external source due to such thoughts being inconsistent with the person's beliefs about his or her own mental processes (metacognitive beliefs). The aim of this study was to investigate the applicability of this model to psychotic symptoms of thought interference. Fifty psychotic patients with and without thought interference were compared on (i) frequency of cognitive intrusions, (ii) metacognitive beliefs, (iii) source monitoring and (iv) appraisals of an unrelated anomalous event (a card trick). As predicted, individuals with thought interference had an increased frequency of cognitive intrusions and of maladaptive metacognitive appraisals, lower perceived cognitive control, and were more likely to endorse appraisals regarding 'permeability' of the mind, on the card trick task, in comparison to individuals without thought interference. No significant differences were found on any measure when the patient group was divided into hallucinators and non-hallucinators, once other variables were controlled for. These findings suggest that Morrison's model may be more parsimonious for symptoms of thought interference than for auditory hallucinations. Keywords: Psychosis; Thought interference; Auditory hallucinations; Cognitive intrusions; Appraisals

The present study proposes a new executive task, the one-back choice reaction time (RT) task, and implements the selective interference paradigm to estimate the executive demands of the processing components involved in this task. Based on the similarities between a one-back choice RT task and the n-back updating task, it was hypothesized that one-back delaying of a choice reaction involves executive control. In three experiments, framed within Baddeley's (1986) working-memory model, a one-back choice RT task, a choice RT task, articulatory suppression, and matrix tapping were performed concurrently with primary tasks involving verbal, visuospatial, and executive processing. The results demonstrate that one-back delaying of a choice reaction interferes with tasks requiring executive control, while the potential interference at the level of the verbal or visuospatial working memory slave systems remains minimal.

Building on 2 previous studies (B. R. Ekstrand, 1967; B. R. Ekstrand, M. J. Sullivan, D. F. Parker, & J. N. West, 1971), the authors present 2 experiments that were aimed at characterizing the role of retroactive interference in sleep-associated declarative memory consolidation. Using an A-B, A-C paradigm with lists of word pairs in Experiment 1, the authors showed that sleep provides recovery from retroactive interference induced at encoding, whereas no such recovery was seen in several wake control conditions. Noninterfering word-pair lists were used in Experiment 2 (A-B, C-D). Sleeping after learning, in comparison with waking after learning, enhanced retention of both lists to a similar extent when encoding was less intense because of less list repetition and briefer word-pair presentations. With intense encoding, sleep-associated improvements were not seen for either list. In combination, the results indicate that the benefit of sleep for declarative memory consolidation is greater for weaker associations, regardless of whether weak associations result from retroactive interference or poor encoding. Keywords: memory, consolidation, sleep, interference, recovery

Three visual selective attention tasks were used to measure potential differences in susceptibility to interference and inhibitory cognitive control processes in 16 adolescents diagnosed with attention deficit hyperactivity disorder (ADHD) and 45 similar-aged controls. Susceptibility to interference was assessed using the Stroop color and word naming test. Efficiency of distractor inhibition was assessed in two conceptual negative priming tasks. The majority of studies in this area indicate that people with ADHD demonstrate higher levels of interference and lower negative priming effects in comparison with age-matched peers. However, we found that although the ADHD group was consistently slower to name target stimuli than the control group, there were no differences in interference or negative priming between the two groups.

We examined age-group differences in a saccadic interference task, which requires that participants execute a saccade (eye movement) toward an abrupt-onset visual target presented to the right or left of fixation. On some trials, we imposed diffuse interference by bilateral (top and bottom) flashes of light presented 20 to 210 ms after target onset. When the flashes followed the cue at shorter intervals, time to execute a saccade was slowed relative to no-flash trials. This slowing was greater and sustained over a larger cue--flash interval for older participants than for the young participants. The results indicate that, when diffuse distractors are used, older adults are more susceptible to saccade disruption than are young adults.

Three experiments examined the functional relationship between the frequency of prospective responding and the prospective interference effect within the context of a task switching paradigm. Prospective responding was less frequent across the experiments when prospective cues appeared in switch blocks than when they appeared in pure blocks. The magnitude of the prospective interference effect for response time (RT) was similar for pure and switch blocks when exogenous task cuing was used, and was greater for switch blocks than for pure blocks when endogenous task cuing was used. These data reveal a dissociation between the effect of task switching on the frequency of prospective responding and the prospective interference effect, and indicate that the functional relationship between these two measures is dependent on task demands.

In three experiments, we examined mediated learning in situations involving learning a large amount of information. Participants learned 144 'facts' during a learning phase and were tested on facts during a test phase. In Experiments 1 and 2, participants learned facts about familiar individuals, unfamiliar individuals, or unfamiliar individuals associated with familiar individuals. Prior knowledge reduced interference, even when it played only a mediating role. In Experiment 3, participants learned facts about unfamiliar individuals or unfamiliar countries, with half the participants in each group associating the unfamiliar items with familiar individuals. Again, use of prior knowledge to mediate learning reduced interference even when the new information was conceptually dissimilar to the previously known information. These results are consistent with the mental model account of long-term memory.

Task interference occurs in prospective memory tasks when an intention deleteriously affects performance on an ongoing activity in some way. Several studies have shown that task interference can manifest itself in slower latencies to perform an ongoing task. Recent evidence demonstrates that associating intentions to certain performance contexts affects prospective memory performance (see, e.g., Cook, Marsh, & Hicks, 2005). In the present study, an intention was associated with a particular stimulus class, such as pictures or words. We found that task interference could be reduced when participants could reliably predict that the material about to be processed was irrelevant to the intention. This material-specific interference effect was found on a trial-by-trial basis in a random sequence of two different kinds of materials across two experiments and with blocking manipulation in another experiment. These results demonstrate that task interference is not a monolithic construct; rather, it results from dynamic and flexible attentional allocation strategies that can change on a trial-by-trial basis.

To investigate the interference effect in volleyball players and nonathletes (ns=10) when they executed both saccadic and key-press reaction time (RT) tasks concurrently, the two groups responded to the onset of peripheral visual stimuli as quickly as possible in single and dual conditions. In the single condition, subjects responded with either saccadic eye or key-press movement. In the dual condition, they responded concurrently with both saccadic eye and key-press movements. In both groups, the key-press RT was longer in the dual condition than in the single condition. However, the amount of key-press RT delay was remarkably smaller for the volleyball players than for nonathletes. This suggests the motor command to initiate manual movement of volleyball players might be less interfered with by a concurrent oculomotor command to initiate saccadic eye movement when compared to that of nonathletes.

Domestic cats (Felis catus) received a task in which an obstacle was introduced at the time they were ready to reach for 1 among 2 or 3 baited targets. The results revealed that when the initially chosen direction (i.e., before the introduction of the obstacle) and the new one were orthogonal, the cats reassessed distance, angular deviation, and visibility once they had turned around the obstacle (Experiments 1,2, and 3). Then the cats chose a different target than the one that would have been chosen had there been no obstacle. When both the initially chosen and the new direction matched (Experiment 4), the cats kept intact their initial decision. The discussion focuses on the nature of the representational system of the cat. The discussion also emphasizes comparisons with dogs (i.e., cooperative hunters). Keywords: decision making, interference, cats, visibility, distance

Paired associates and serial list memory are typically investigated separately. An 'isolation principle' (J. B. Caplan, 2005) was proposed to explain behavior in both paradigms by using a single model, in which serial list and paired associates memory differ only in how isolated pairs of items are from interference from other studied items. In the present study, 2 experiments identify a critical dissociation between the 2 paradigms, challenging this unified account. Specifically, forward and backward probes were highly correlated for pairs and less so for short lists (triples). The authors asked whether the isolation principle could quantitatively accommodate this type of dissociation. A simulation confirmed that a single model incorporating the isolation principle can adequately explain this and other dissociations, supporting the common processes view.

The nature of working memory operation during complex sentence comprehension was studied by means of eye-tracking methodology. Readers had difficulty when the syntax of a sentence required them to hold 2 similar noun phrases (NPs) in working memory before syntactically and semantically integrating either of the NPs with a verb. In sentence structures that placed these NPs at the same linear distances from one another but allowed integration with a verb for 1 of the NPs, the comprehension difficulty was not seen. These results are interpreted as indicating that similarity-based interference occurs online during the comprehension of complex sentences and that the degree of memory accessibility conventionally associated with different types of NPs does not have a strong effect on sentence processing. Keywords: language, comprehension, memory, parsing, interference

The negative effects of false information presented either prior to (proactive interference; PI) or following (retroactive interference; RI) true information was examined with word definitions (Experiment 1) and trivia facts (Experiment 2). Participants were explicitly aware of which information was true and false when shown, and true--false discrimination was evaluated via multiple-choice tests. Negative suggestion, defined as poorer performance on interference items than noninterference (control) items, consistently occurred when the wrong information followed the correct information (RI) but not when it preceded the correct information (PI). These effects did not change as a function of retention interval (immediate, 1 week, or 3 weeks) or number of incorrect alternatives (1 or 3). Implications of this outcome for experiencing incorrect information in both academic and nonacademic situations are considered. Keywords: negative suggestion, proactive interference, retroactive interference

We assessed age differences in interference effects in priming by using fragment completion. In Experiment 1, noninterfering filler words preceded critical targets at study, and priming was age invariant. In Experiment 2, the same target items had interfering competitors at the beginning of the list, such that both the target and the competitor were legitimate solutions to a fragment. Having two responses to a cue was disruptive for older adults, but not for younger adults. Younger and older adults differ in their susceptibility to interference in implicit tasks, and interference may play a role in influencing the magnitude of age differences in priming.

Tehan and Humphreys's (1995, 1996) short-term cued recall paradigm showed that recall in short-term memory is cue driven. In critical trials, the participants studied two blocks of four words each and were required to forget the first block while remembering the second block. A foil in the first block (e.g., orange) was related to a target (e.g., carrot) in the second block. Proactive interference (PI) was evident when a retrieval cue was used that subsumed the foil and the target (e.g., type of juice), but not when a cue was used that subsumed only the target (e.g., type of vegetable). Four experiments were performed to examine the extent to which contextual organization in the foil block would enhance or diminish the foil's efficacy in creating PI. A novel condition was included in which the words in the foil block were studied in a phonologically related context but the target was cued semantically, and vice versa with a semantic context and phonological cue. There were no differences in recall accuracy between conditions with and without contextual organization, but reliable increases in foil intrusions were observed when contextual organization was present. Contextual organization enhanced the foil, rather than diminished it, but the strengthened foil generated PI only when the cue subsumed the foil and the target and had no effect when the cue subsumed only the target. The results are consistent with a cue-driven retrieval interpretation of short-term recall.

One of the current issues in the field of prospective memory concerns whether having an intention produces a cost to other ongoing activities (called task interference). The evidence to date suggests that certain intentions held over the shorter term do interfere with other tasks. Because the cumulative effect of such costs would be prohibitively expensive in everyday life, the present study examined one means by which that interference may be reduced. Participants who formed a specific association to fulfilling an intention in a future context did not exhibit task interference over the intervening period until that context was encountered. This outcome was observed with both an event-based and a time-based prospective memory task. The results suggest that associating intention fulfillment with a specific context can eliminate task interference, and they emphasize the importance of studying intentions that are linked to future contexts versus those that are not.

The effect of a working-memory--demanding dual task on perceptual category learning was investigated. In Experiment 1, participants learned unidimensional rule-based or information integration category structures. In Experiment 2, participants learned a conjunctive rule-based category structure. In Experiment 1, unidimensional rule-based category learning was disrupted more by the dual working memory task than was information integration category learning. In addition, rule-based category learning differed qualitatively from information integration category learning in yielding a bimodal, rather than a normal, distribution of scores. Experiment 2 showed that rule-based learning can be disrupted by a dual working memory task even when both dimensions are relevant for optimal categorization. The results support the notion of at least two systems of category learning: a hypothesis-testing system that seeks verbalizable rules and relies on working memory and selective attention, and an implicit system that is procedural-learning based and is essentially automatic.

Proactive interference (PI) may influence the predictive utility of working memory span tasks. Participants in one experiment (N = 70) completed Ravens Advanced Progressive Matrices (RAPM) and multiple versions of operation span and probed recall, modified for the type of memoranda (digits or words). Changing memoranda within- or across-trials released PI, but not doing so permitted PI buildup. Scores from PI-build trials, but not PI-release trials, correlated with RAPM and accounted for as much variance in RAPM as unmodified tasks. These results are consistent with controlled attention and inhibition accounts of working memory, and they elucidate a fundamental component of working memory span tasks. Keywords: attentional control, inhibition, operation span, probed recall, working memory

Two experiments used visual-, verbal-, and haptic-interference tasks during encoding (Experiment 1) and retrieval (Experiment 2) to examine mental representation of familiar and unfamiliar objects in visual/haptic crossmodal memory. Three competing theories are discussed, which variously suggest that these representations are: (a) visual; (b) dual-code--visual for unfamiliar objects but visual and verbal for familiar objects; or (c) amodal. The results suggest that representations of unfamiliar objects are primarily visual but that crossmodal memory for familiar objects may rely on a network of different representations. The pattern of verbal-interference effects suggests that verbal strategies facilitate encoding of unfamiliar objects regardless of modality, but only haptic recognition regardless of familiarity. The results raise further research questions about all three theoretical approaches.

In the present study, the relation between interference at the early processing stages and response inhibition was investigated. In previous studies, response stopping appeared to be slowed down when irrelevant distracting information was presented. The purpose of the present study was to further explore the relationship between interference control and response inhibition. In Experiment 1, a stop signal paradigm was combined with a global/local task. The typical global-to-local interference effect is generally attributed to early processing stages, such as stimulus perception and identification. Results of this experiment demonstrated a congruency effect for both reaction time data and stopping performance. In Experiment 2, these results were replicated with a flanker task that used stimulus-incongruent but response-congruent flankers. Results of both experiments suggest that response inhibition and interference at the early processing stages interact.

Resistance to interference was examined in rats that received a complex negative patterning discrimination in which XA and XB were followed by food reinforcement and XAB was not. Retention of the discrimination was evident after separate reinforcement of both A and B (Experiment 3), but not after reinforcement of either AB (Experiments 1 and 3) or XAB (Experiments 2 and 3). These data suggest that complex negative patterning discriminations are acquired configurally and that the relative similarity of the original discrimination and subsequent interference trials dictates the final degree of retention observed.

This study examined the influence of interracial interaction on the cognitive functioning of members of a dominant racial group. White participants had a brief interaction with either a White or a Black confederate, and then completed an ostensibly unrelated Stroop color-naming test. Prior to the interaction, participants' racial attitudes regarding Whites and Blacks were measured via the Implicit Association Test. Racial attitudes were predictive of impairment on the Stroop test for individuals who participated in interracial interactions, but not for those who participated in same-race interactions. The results are consistent with recently proposed resource models of self-regulation and executive control in that interracial interaction, a particularly taxing exercise of self-regulation for highly prejudiced individuals, negatively affected performance on a subsequent, yet unrelated, test of executive function.

We investigated the role of cross-modal links in spatial attention in modulating the efficiency of dual-task performance. The difficulty of combining speech shadowing with a simulated driving task was modulated by the spatial location from which the speech was presented. In both single- and dual-task conditions, participants found it significantly easier to shadow one of two auditory streams when the relevant speech was presented from directly in front of them, rather than from the side. This frontal speech advantage was more pronounced when participants performed the demanding simulated driving task at the same time as shadowing than when they performed the shadowing task alone. These results demonstrate that people process auditory information more efficiently (with a lower overall dual-task decrement) when relevant auditory and visual stimuli are presented from the same, rather than different, spatial locations. These results are related to recent findings showing that there are extensive cross-modal links in spatial attention, and have clear implications for the design of better user interfaces.

Stroop effects might be due to differences in stimulus-response compatibility (SRC) and/or to differences in stimulus-stimulus compatibility (SSC). Recent evidence for the role of SSC is inconclusive, because there were no controls for effects of SRC that are based on short-term associations between stimuli and responses (i.e., associations set up as the result of task instructions). In two experiments, SRC effects were controlled for. Regardless of whether the irrelevant and the relevant stimulus features were separated (Experiment 1) or integrated in one stimulus (Experiment 2), the results revealed an effect of SSC and an effect of SRC that was based on short-term associations. The results thus confirm that both processes at the level of encoding and processes at the level of response selection contribute to the Stroop effect.

Duration of practice trial on a pursuit rotor task in contextual interference was investigated. Participants practiced at each of 4 angular velocities, with 24 participants completing 28 trials lasting 20 sec., and 24 participants completing 112 trials of 5 sec. Half of the participants in each trial-duration condition practiced in a blocked format and half practiced in a random format. After random practice posttest performance was better than blocked practice when practice-trial duration was 20 sec., but worse when practice-trial duration was 5 sec. This result is not consistent with theoretical explanations of the contextual interference effect and is discussed with reference to the task characteristics and demands of the pursuit rotor.

This article explored the extent to which stimulus-driven control over visual selection is modulated by goal-driven factors. Observers searched for a no-onset color target among 3 distractors and signaled its location either manually or with a saccade. Additional distractors appeared either with or without an abrupt onset and were either similar or dissimilar to the target. Abrupt onsets disrupted saccades to the target, especially when they shared the target color. Irrelevant onsets also interfered with the manual responses, but this interference was dependent on the particular type of manual response. Stimulus-driven and contingent capture can occur within a single paradigm, but the extent and nature of these effects depend on the specific response required.

The role of attention in speeded Garner classification of concurrently presented auditory and visual signals was examined in 4 experiments. Within-trial interference (i.e., congruence effects) occurred regardless of the attentional demands of the task. Between-trials interference (i.e., Garner interference) occurred only under conditions of divided attention when making judgments about auditory signals. Of importance, the data show congruence effects in the absence of Garner interference. Such a pattern has been rarely reported in studies of the classification of purely visual stimuli and contradicts theoretical accounts asserting that the effects share a common locus. The data question the notion that Garner classification reveals fundamental insights about the nature of the perceptual processing of bimodal stimuli.

Providing participants with a preview of half the distractors in a visual search task facilitates performance. The present study examined the effects of secondary tasks on the preview benefit in search. Participants had to attend to a visual or an auditory stream of digits that began either (a) at the onset of the preview or (b) after the preview. Secondary tasks that onset with the preview disrupted the preview benefit irrespective of their modality. Only visual secondary tasks disrupted the benefit in the delayed condition. These selective interference effects suggest that the preview benefit can be fractionated into 2 components: an initialization component that involves modality-independent resources and a maintenance component that depends on visual resources. Results are discussed in relation to theoretical accounts of the preview benefit in search.

Students participated in 3 experiments investigating the use of environment- and action-centered reference frames in selective reaching. They pointed to a green target appearing either with or without a red distractor. Target-distractor distance was manipulated, and distractor interference (difference between distractor trials and no-distractor trials) was measured in reaction time, movement time, and movement endpoint. Target-distractor distance determined the dominant frame of reference. Small distances evoked an environment-centered framework that encoded targets within an external context. Large distances evoked an action-centered framework that encoded targets relative to the start position of the hand. Results support the hypothesis that the brain represents spatial information in multiple frames of reference, with the dominant frame of reference being dependent on the task demands.

The irrelevant-speech effect refers to the finding of impaired recall performance in the presence of irrelevant auditory stimuli. Two broad classes of theories exist for the effect, both allowing automatic entry of the distracting sounds into the processing system but differing in how attention is involved. As one source of evidence in the discussion of existing theories of the irrelevant-speech effect, the performance of children and adults on a visual serial recall task with irrelevant sounds (speech and tones) was examined. The magnitude of the effects of irrelevant sounds on performance decreased with age. The developmental differences were marked in the conditions with the greatest need for attentional control (words and especially changing words). The findings were interpreted with respect to current models of memory. Theories of the irrelevant-speech effect that include a role for attentional control were better suited to handle the results than those without a specified role for attention.

Predicted to diminish task performance were (a) distraction by telephone conversation and (b) older age. 38 participants pointed to letters on a randomized or alphabetized letter matrix during distraction by telephone conversation or no distraction. In a within-subjects design, telephone conversation negatively affected completion time but there were no age differences. Implications for cellular telephone use while driving are discussed.

INTRODUCTION Over the past 10 years there has been an explosive worldwide growth in the use of cellular telephones. In the United States, for example, the number of users increased […], The effect of a concurrent auditory task on visual search was investigated using an image-flicker technique. Participants were undergraduate university students with normal or corrected-to-normal vision who searched for changes in images of driving scenes that involved either driving-related (e.g., traffic light) or driving-unrelated (e.g., mailbox) scene elements. The results indicated that response times were significantly slower if the search was accompanied by a concurrent auditory task. In addition, slower overall responses to scenes involving driving-unrelated changes suggest that the underlying process affected by the concurrent auditory task is strategic in nature. These results were interpreted in terms of their implications for using a cellular telephone while driving. Actual or potential applications of this research include the development of safer in-vehicle communication devices.

This article examines the effects of exposing German subjects to distractor words immediately prior to a picture-word naming task. Findings indicate that priming subjects with phonologically related distractors has a facilitatory effect on the naming response when compared to neutral distractors.

Research shows that interference between elementally trained cues usually happens during retrieval rather than because of the inhibitory associations between an absent cue and the result. This result pertains even if two cues had not been given compound training.

A series of experiments shows that the effect of an observed causal movement influences its representation. Topics discussed include theories of retroactive interference and false post-event information.

The degree of interference from multi-dimensional distractors in a two-choice response time task depends on three factors: discriminability of incompatible features of the distractor that are relevant to the task, the number of distractor features that are incompatible and task-relevant, and the matching between task goals and the incompatible, task-relevant features. Discussion covers conjunction benefits, flanker interference and task goals, and the effect of discriminability and number of incompatible flanker features on conjunction judgments.

The interference effects of non-relevant objects on reach-to-grasp movements has been investigated. The influence of different features of the distractor, such as size, position, and orientation, was studied.

Aspects of the visuo-spatial component of working memory have been investigated in a series of experiments focusing on conditions under which interference affects the passive visual store. Results suggest that the passive visual store has temporal and capacity characteristics, is susceptible to decay over time, and has more effect on a concurrent task when changes within it are more numerous.

Observers viewed a screen on which a number of patches containing horizontally moving pixels were presented. Target patches consisted of pixels whose motion simulated the rotation of a cylinder around its Y-axis; distractors, of pixels whose motion was linear. The task was to assess whether a display contained a target patch. Exp. 1 showed that the superposition of the displays with drifting sine-wave gratings interfered with rotation detection in a spatial- and temporal-frequency specific manner. In Exp. 2, dichoptic presentation greatly reduced the interference of the drifting gratings. It is argued on various grounds that the process(es) responsible for the detection and discrimination of rotating structure in depth exists at a low level of the visual system.

Four experiments were conducted using a flanker task with 1 distractor appearing either on the left or right side of a central target. Responses were made on a keyboard aligned parallel to the displays. A larger flanker effect was obtained when the distractor was on the same side as the response. Two factors account for this asymmetry. First, when the flanker and target are identical, the 2 form a group that is assigned a spatial tag, creating a form of the Simon effect on the basis of the compatibility between the response keys and the group. Second, preparation of a lateralized response appears to entail a shift of visual attention in the corresponding direction, thus enhancing processing of the flanker on the response side. Consistent with the 2nd hypothesis, participants were more likely to correctly recognize letters that were briefly presented at the distractor position on the same side as the response.

The probe reaction time paradigm was used to investigate the processing demands of an elbow extension and 2 types of extension-flexion movements, one with a short pause time (50-100 ms) at reversal and another with a long pause time (250-300 ms). The probe task consisted of a bite response to an auditory signal. The locations of the probe were determined by on-line analysis of electromyographic activity and kinematic profiles. Depending on the temporal location of the probe relative to the initiation of the flexion phase, participants either initiated the masseter and biceps muscles successively or grouped them together as a single conjoint response. Results are discussed in terms of limitations during the on-line preparation and execution of movements.

Can people learn to perform two tasks at the same time without interference? To answer this question, the authors trained 5 participants for 36 sessions in a Psychological Refractory Period (PRP) experiment, where Task 1 required a speeded vocal response to an auditory stimulus and Task 2 required a speeded manual response to a visual stimulus. The large PRP effect found initially (353 ms in Session 1) shrank to only about 40 ms over the course of practice, disappearing entirely for 1 of the 6 participants. This reduction in the PRP effect with practice is considerably larger than has been previously reported. The obtained pattern of factor interactions between stimulus onset asynchrony and each of three task difficulty manipulations (Task 1 judgment difficulty, Task 2 stimulus contrast, and Task 2 mapping compatibility) supports a postponement (bottleneck) account of dual-task interference, both before and after practice.

Three experiments examined whether interhemispheric interaction modulates selective attention in a same-different version of D. Navon's (1977) global-local paradigm. In Experiments 1 and 2, interhemispheric interaction reduced interstimulus interference produced when two stimuli matched at a preassigned level (e.g., local) but differed at the irrelevant level (e.g., global). This effect was greater for stimuli made of a few large elements than for those made of many small elements. Experiment 3 demonstrated that (a) the ability of interhemispheric interaction to reduce interstimulus interference is not constrained by hemispheric differences for global and local processing and (b) interhemispheric interaction does not strongly modulate intrastimulus interference produced when the forms at the preassigned (e.g., local) and irrelevant (e.g., global) levels differ within an individual stimulus. These finding indicate that interaction between the hemispheres is a neural mechanism that may aid selective attention.

In two experiments, we investigated the possibility that susceptibility to proactive interference (PI) affects performance on memory span measures. We tested both younger and older adults (older adults were tested because of the suggestion that they are differentially susceptible to PI). We used two different span measures and manipulated testing procedures to reduce PI for these tasks. For older adults, span estimates increased with each PI-reducing manipulation; for younger adults, scores increased when multiple PI manipulations were combined or when PI-reducing manipulations were used in paradigms in which within-task PI was especially high. The findings suggest that PI critically influences span performance. We consider the possibility that interference-proneness may influence cognitive behaviors previously thought to be governed by capacity.

A visual target (T(sub 2)) containing either 1 or 2 letters, or a random 10-sided polygon, was presented after an auditory target (T(sub 1)) at a stimulus onset asynchrony (SOA) of either 50, 150, 250, or 600 ms. Task(sub 1) was a speeded pitch discrimination to the tone, and across experiments, T(sub 1) was either 1 of 2 tones (2-alternative discrimination [2AD]) or 1 of 4 tones (4-alternative discrimination [4AD]). Memory for the visual information decreased as SOA was reduced when a mask was used, but not when there was no mask. The effects of SOA were larger for the 4AD Task(sub 1) than the 2AD Task(sub 1). The results demonstrate cross-modal, dual-task interference on visual encoding and suggest central interference with the short-term consolidation of visual information in short-term memory.