High Interference Conditions Research Articles

Target—distractor interference in the attentional blink implicates the locus coeruleus—norepinephrine system

We provide evidence that the locus coeruleus-norephinephrine (LC-NE) system is the neurophysiological basis of the attentional blink. The attentional blink refers to decreased accuracy for reporting the second of two targets in a rapid serial visual presentation of distractors. The LC-NE account of the attentional blink posits that targets elicit a facilitative LC-NE system response that is available for the first target but subsequently unavailable to the second, due to the autoinhibitory nature of the LC-NE system. We propose a modification of the LC-NE account, suggesting that the LC-NE system response is elicited by interference between mutually exclusive responses demanded by temporally proximal targets and distractors. We increased the interference between the first target and the following distractor by reducing the time between them. For identifying the second target this high-interference condition yielded a benefit up to 200 msec after onset of the first, followed by a decrease in accuracy. Consistent with our modification of the LC-NE account, this result suggests a temporarily enhanced LC-NE system response to increased target-distractor interference.

Rumination and impaired resource allocation in depression.

Depression is characterized by a range of cognitive deficits that theorists posit are due to the resource capturing properties of rumination. The present study was designed to examine the relation between rumination and resource allocation in depression. Twenty-five depressed and 25 nondepressed participants completed a modified dual-task version of the recency-probes task, which assesses the controlled allocation of cognitive resources by comparing performance across low- and high-interference conditions. In low-interference conditions, participants performed either the recency-probes task or a tracking task, which required participants to track specific stimuli across trials (i.e., no dual-task interference). In the high-interference condition, participants performed both the recency-probes task and the tracking task, which required the controlled allocation of resources to resolve dual-task interference. Depressed participants performed significantly worse than did their nondepressed counterparts in only the high-interference condition; performance of the 2 groups was comparable in the low-interference conditions. Furthermore, the degree to which depressed participants were impaired in the high-interference condition was correlated .74 with rumination. These findings suggest that an association between rumination and impairments in resource allocation underlies the cognitive difficulties experienced by depressed individuals.

Age differences in visuospatial working memory.

In two visuospatial working memory (VSWM) span experiments, older and young participants were tested under conditions of either high or low interference, using two different displays: computerized versions of a 3 x 3 matrix or the standard (randomly arrayed) Corsi block task (P. M. Corsi, 1972). Older adults' VSWM estimates were increased in the low-interference, compared with the high-interference, condition, replicating findings with verbal memory span studies. Young adults showed the opposite pattern, and together the findings suggest that typical VSWM span tasks include opposing components (interference and practice) that differentially affect young and older adults.

Input and output modality effects in immediate serial recall

In immediate recall tasks, visual recency is substantially enhanced when output interference is low (Cowan, Saults, Elliott, & Moreno, 2002; Craik, 1969) whereas auditory recency remains high even under conditions of high output interference. This auditory advantage has been interpreted in terms of auditory resistance to output interference (e.g., Neath & Surprenant, 2003). In this study the auditory-visual difference at low output interference re-emerged when ceiling effects were accounted for, but only with spoken output. With written responding the auditory advantage remained significantly larger with high than with low output interference. These new data suggest that both superior auditory encoding and modality-specific output interference contribute to the classic auditory-visual modality effect.

Uplink Capacity/Coverage Analysis of WCDMA with Switched Beam Smart Antennae

Capacity and coverage represent, in addition to QoS, the three main requirements for W-CDMA based 3G mobile communication systems. These are conflicting requirements; i.e., optimizing one will be on the account of the other two. All three, however, depend largely on the interference levels in the system. Improvements on interference are thought to have a decisive effect on the performance of the 3G system and one important interference reduction technique is the utilization of smart antennae. In this paper, we analyze capacity/coverage on the uplink in W-CDMA system utilizing switched beam smart antennae, SBSA, using a simple model of the antenna, while satisfying a certain minimum level of QoS. Limits imposed by both interference from others and the limited uplink power available to any user in the cell are considered. Results of this paper are analytical formulae for capacity/coverage that take into consideration many of the important parameters of either the antennae or the WCDMA system. A sectional view of improvement gains, if any, of either capacity or coverage upon antenna upgrading/downgrading is provided. It is shown that improvements by the directional SBSA of either capacity or coverage, are only attained at high interference conditions; i.e., higher number of users when considering coverage improvement or smaller coverage areas when considering capacity. The higher the interference conditions are the higher gain over side lobes or more beams SBSA are needed to attain improvement.

The contextual interference effect in applied settings

This paper analyses the research literature that approaches the contextual interference effect in applied settings. In contrast to the laboratory settings, in which high interference conditions depress acquisition and promote learning evaluated in retention and transfer tests, in applied settings most of the studies (60%) fail to observe positive effects after manipulation of the contextual interference. Some possible explanations for the fact are hypothesized regarding the characteristics of the task, with serial tasks doing best, shor t inter trial intervals rare in applied settings, interference produced by the use of different motor programmes and the possible interference of concurrent feedback in slow tasks in contrast to ballistic skills. It seems that there is a more evident contextual interference effect in an applied setting, when subject learns a serial task with high degree of complexity.

How people cope with uncertainty due to chance or deception

In making social judgments people process effects caused by humans differently from effects caused by non-human agencies. We assume that when they have to predict outcomes that are attributed to non-human causes, people acknowledge their ignorance and try to focus on what is most diagnostic. However, when events are attributed to human agency, they believe that nothing is arbitrary and that one can understand the decision situation well enough to eliminate error. If so, then people should behave differently when an uncertainty is attributed to chance (a non-human agency) or to deception (a human agency). We tested this prediction using the probability-matching paradigm and found reasonable support for our analysis in four experiments. Individuals who attributed uncertainty to deception were less likely to adopt the optimal rule-based strategy than those who attributed it to chance. Indeed, only when the former were prevented from thinking about and elaborating the outcomes (the high-interference condition in Experiment 3) was their performance comparable to the level of individuals in the chance condition.

Paradoxical effects of information presentation formats and contextual interference on transfer of a complex cognitive skill

In a 2x2 factorial design the effects of (1) information presentation format and (2) contextual interference on training behavior, transfer performance and mental effort were studied for learning troubleshooting skills with a computer-based simulation. Participants studied information about the functioning of an alcohol distillery system (system principles) prior to practicing troubleshooting skills. Regarding the first factor, an expository (Exp) format, in which system principles, examples and a troubleshooting strategy were presented in a textual form, was compared to an inquisitory (Inq) format, in which participants had to predict the behavior of the system after they studied the system principles and in which demonstrations of the troubleshooting strategy were given. With regard to the second factor, a low contextual interference (LCI) condition in which participants practiced to diagnose types of system failures in a blocked schedule was compared to a high contextual interference (HCI) condition, in which different failure types were practiced in a random schedule. The main hypothesis is that the Inq and HCI conditions promote the development of cognitive schemata that enable learners to diagnose a malfunctioning system component by interpreting symptoms in terms of violations of system principles. Hence, they are expected to show higher transfer performance than participants in the traditional Exp and LCI conditions, who are believed to develop schemata containing associations between symptoms and malfunctioning components that are context-bound and less useful for diagnosing new failures. Contrary to the predictions, the traditional conditions (Exp and LCI) showed higher performance on a transfer test two weeks after training. Possible explanations for this result are discussed.

A common parieto-frontal network is recruited under both low visibility and high perceptual interference conditions.

A fundamental property of visual attention is to select targets from interfering distractors. However, attention can also facilitate the detectability of near-threshold items presented in isolation. The extent to which these two perceptually challenging conditions are resolved by the same neural mechanisms is not well known. In the present event-related fMRI experiment, subjects performed a letter identification task under two perceptually challenging conditions; when the luminance contrast of a target letter was reduced (perceptual visibility manipulation) and when the target letter was flanked by distractors (perceptual interference manipulation). Perceptual interference recruited the right parietal and mid-lateral frontal cortex, while perceptual visibility activated these regions bilaterally. The overlap of activated areas between the two perceptual manipulations suggests that a single parieto-frontal network is summoned under both perceptual visibility and interference conditions.

Advance preparation of set-switches in Parkinson’s disease

Eighteen patients with Parkinson’s disease (PD) and 18 healthy control subjects were presented with a switching task where stimuli elicited either one (no-conflict condition) or two (conflict condition) task-relevant stimulus-response mappings. The response stimulus interval (RSI) between trials was varied to allow investigation of the extent to which participants engaged in advanced preparation of task set. In line with previous findings, set-switching deficits of PD patients were only observed in the conflict condition. Prolonging the RSI led to a reduction of switch costs for control subjects in both the conflict and the no-conflict task, whereas this effect was attenuated for PD patients in the conflict condition. This deficit was explained in terms of a reduced ability to maintain cue-action representations active in working memory in high interference conditions, and was related to the possible role of the frontostriatal circuit in maintaining focussed attention.

A novel drag test to evaluate media tribology design on head wear

By changing the head's Z-height, a new accelerated drag test has been developed to characterize head wear under high interference conditions. Compared to contact start stop (CSS) and other drag tests, heads wear faster in our approach, due to the stressed condition at the tilted trailing edge. The optimized Z-height has been chosen so that the head-disk interference and acoustic emission are maximized. The wear volume can be estimated by optical microscopy. The influence of lube bonded ratio and X1P additive amount on head wear has been studied for AM3001 lubricant. Lower bonded ratio and higher X1P additive were found to give rise to less head wear, which is in agreement with the existing results of contact start-stop and other drag tests. In media manufacturing, tape burnish processes were found to significantly affect the bonded ratio in the AM3001/X1P lubricant system, which consequently affects head wear. Short tape burnish times were found to reduce the media's head wear.

High versus low contextual interference in simulation-based training of troubleshooting skills: effects on transfer performance and invested mental effort

The effects of contextual interference on practice behavior, transfer performance, and cognitive load for learning troubleshooting skills were studied. A low contextual interference (LCI) condition, in which subjects practiced to diagnose system failures in a blocked schedule, was compared with a high contextual interference (HCI) condition, in which failures were practiced in a random schedule. The following hypotheses are stated. Hypothesis 1: during practice, subjects in the HCI group will require more time to reach a high performance level (i.e., more accurate and/or faster diagnoses of system failures) on practice problems and will have to invest more mental effort relative to subjects in the LCI group. Hypothesis 2: subjects in the HCI group will show higher performance and lower invested mental effort on far transfer test problems, relative to subjects in the LCI group, but there will be no difference between the groups on near transfer test problems. The results showed that subjects in the HCI group were more accurate in diagnosing far transfer problems, although during practice they needed more time to diagnose system failures and made significantly more incorrect diagnoses.

Contextual interference and teaching golf skills.

This study was designed to examine the contextual interference effect on teaching golf skills in a naturalistic setting to 2 groups of 18 novice golfers who as undergraduate students practiced four foundational skills under conditions of low and high contextual interference, respectively. A t test for independent samples indicated no significant differences between groups. Findings are discussed and recommendations for research are made.

Appropriate summary KR for learning timing tasks under conditions of high and low contextual interference

Recall and retrieval processes of timing tasks were investigated in a multitask learning experiment using blocked (BL) and random (RA) practice schedules (Battig 1979). The extent to which summary knowledge of results (KR) interacts with order of presentation of practice tasks was the primary topic under investigation. It has been suggested that summary KR may enhance processing of task-relevant information (Schmidt 1991). The processing benefits of summary KR however may be dependent on the presentation order of practice tasks. Seventy-two females responded to the apparent motion of illuminated lights set at three speeds of 224, 313, and 492 cm/s during 90 acquisition, 30 no-KR retention and 20 transfer trials. Subjects' tasks was to push a ball hinged to a lever to coincide with the arrival of a light at a predetermined intercept point. Retrospective verbal reports were obtained immediately following transfer to ascertain the nature of subjects' processing activities. Error data were analyzed on four dependent variables. The most important finding was that longer summary KR lengths for RA subjects (KR10) were beneficial in acquisition and transfer. In contrast, BL subjects were more consistent in transfer if they received KR after each practice trial. A similar trend ( p = 0.15) in retention was found in that BL subjects were more consistent as compared to RA, when they learned the tasks with 100% KR. Given the differential results of summary KR for BL and RA, the importance of considering the order of task presentation when investigating summary KR was supported.

Contextual Interference in Motor Learning: Dissociated Effects Due to the Nature of Task Variations

The contextual interference effect in motor learning refers to the interference that results from practising a task within the concept of other tasks in a practice session. Several studies have shown that practice under conditions of high contextual interference (i.e. with a random practice order) degrades performance during acquisition trials, compared to low contextual interference conditions (i.e. with a blocked order, where practice is completed on one task before practice on another task is undertaken). In contrast to acquisition performance, random practice usually leads to more effective learning than blocked practice, as measured by retention and transfer tests. One of the hypotheses regarding the effect suggests that a random practice schedule induces more extensive planning operations during practice than a blocked practice condition. If so, then differences between these two conditions should emerge to the degree that the set of tasks requires complete reconstruction of these planning operations on each trial. To address this issue, we compared four groups of subjects: a blocked and random group that practised three timing tasks that shared a common characteristic (same relative timing), and a blocked and random group that practised three tasks that each had different relative timing structures. Subjects practised these tasks on each of two days, with a retention test and two transfer tests that required either a relative timing structure that had been practised previously or had not previously been practised. No random/ blocked differences occurred regardless of the relative timing of the patterns during acquisition or retention. However, for both transfer tests, random practice enhanced learning only for the group that had practised with tasks that each had different relative timing during acquisition. Implications of these results for an explanation of contextual interference are discussed.

The contribution of elaborative processing to the contextual interference effect.

This study examined the influence of supplemental intertask and intratask processing on the retention of three motor sequences practiced in conditions of high and low contextual interference. Subjects practiced in either a blocked or random practice format and experienced additional intratask processing, intertask processing, or no additional processing. Each of three movement sequences were practiced for 18 trials. The subjects were required to perform the sequences as fast and as accurately as possible. Retention performance and recall of the movement sequences were assessed after a 21-day retention interval. The results replicated those of Wright (1991), indicating a benefit for individuals engaging intertask processing during a low contextual interference practice condition. Furthermore, supplementing random practice with additional intertask processing not only slowed the rate of task acquisition, but also resulted in retention performance that was significantly poorer than that exhibited by individuals exposed to random practice with no additional processing. This suggests there may be a limit to the extent of interference that can be established during practice that will lead to a facilitation in retention performance.

Practice schedule and cognitive style interaction in learning a maze task

AbstractIn the present study the effects of contextual interference on the retention and transfer performance of reflectives and impulsives on a maze task were studied. Forty‐seven subjects were randomly assigned to either a high contextual interference group or to a low contextual interference group. Within the two groups subjects were further classified according to their preferred modes of responding. Retention and transfer were measured immediately following practice and after a 4‐week delay. The dependent variables were tracing time and errors. Reflectives made fewer errors and moved more quickly after practising under conditions of high contextual interference. Impulsives tended to have fewer errors after practising under conditions of high contextual interference but moved more slowly. Based on these results it was suggested that trainers consider individual differences in reflectivity‐impulsivity before designing particular practice schedules.

Age, exercise, and coding performance.

We investigated the effects of exercise on the coding performance of young and older subjects. Hypotheses were tested that exercise either facilitates spatial localization or reduces susceptibility to distraction in older subjects. In a balanced design, we administered Digit Symbol and Symbol Digit coding tasks to exercisers and nonexercisers at two age levels under conditions of low or high within-task interference. The findings showed higher performance by the exercisers than by the nonexercisers only at the older age level and only with the Symbol Digit task. These findings support the hypothesis that exercise compensates for a loss of spatial localization skills with age. We found no evidence that susceptibility to distraction either increased with age or was affected by chronic exercise.

The effects of cigarette smoking on verbal learning and retention.

The effects of smoking a low (.7 mg) and a middle (1.3 mg) nicotine yield cigarette on paired-associate learning and retention under conditions of high and low intralist interference, and on serial learning and retention, were examined in groups of male undergraduate smokers (N = 24). The interaction between nicotine level and task difficulty in paired-associate learning was marginally significant. The 1.3-mg nicotine dose impeded learning under low interference conditions, but facilitated learning of high interference sets. Both nicotine levels significantly improved retention in paired-associate learning; task difficulty appearing to have little relevance. Serial learning data suggested that the effect is shown on long-term, rather than short-term memory.

The feasibility of using spread-spectrum communication systems for the land mobile service on a non-interference basis with other users

This paper examines the conditions which would allow land mobile radio systems using spread-spectrum techniques to share certain r.f. channel allocations on a mutual non-interference basis with the existing users of these channels, namely the television broadcasters. An experimental spread-spectrum communication system has been developed and this has been used to examine the feasibility of bandsharing from the point of view of establishing protection for the television signal from the spread-spectrum interference for imperceptible visual interference on the screen, whilst still allowing adequate reception of the spread-spectrum signal under conditions of high television interference. The results indicate that the spread-spectrum signal must be at least 42 dB below the peak television carrier level at the television carrier frequency for picture quality to be unaffected, and under these conditions an output signal with at least 25 dB signal-to-noise ratio can be obtained from the spread-spectrum receiver.