Double Cue Research Articles

Attention in redundancy masking.

Peripheral vision is limited due to several factors, such as visual resolution, crowding, and attention. When attention is not directed towards a stimulus, detection, discrimination, and identification are often compromised. Recent studies have found a new phenomenon that strongly limits peripheral vision, "redundancy masking". In redundancy masking, the number of perceived items in repeating patterns is reduced. For example, when presenting three lines in the peripheral visual field and asking participants to report the number of lines, often only two lines are reported. Here, we investigated what role attention plays in redundancy masking. If redundancy masking was due to limited attention to the target, it should be stronger when less attention is allocated to the target, and absent when attention is maximally focused on the target. Participants were presented with line arrays and reported the number of lines in three cueing conditions (i.e., single cue, double cue, and no cue). Redundancy masking was observed in all cueing conditions, with observers reporting fewer lines than presented in the single, double, and no cue conditions. These results suggest that redundancy masking is not due to limited attention. The number of lines reported was closer to the correct number of lines in the single compared to the double and the no cue conditions, suggesting that reduced attention additionally compromised stimulus discrimination, andreplicating typical effects of diminished attention. Taken together, our results suggest that the extent of attention to peripherally presented stimuli modulates discrimination performance, but does not account for redundancy masking.

The impact of threat of shock-induced anxiety on alerting, orienting, and executive function in women: an ERP study.

The present study used a combination of the Threat-of-Shock paradigm and the Attention Network Test (ANT) to investigate how induced anxiety affects alerting, orienting, and executive control and whether individual differences in threat sensitivity moderate these effects. Forty-two female subjects completed the ANT task in alternation under shock-threat and no-shock ("safe") conditions while event-related potentials (ERPs) were recorded. The results showed that anxiety induced by the threat of shock had a significant impact on alerting and executive control functions at the neural level. Specifically, alerting-related N1 and stimulus-preceding negativity (SPN) differences between double cue and no cue conditions were greater in the threat versus safe state, suggesting that the induced anxiety promoted the early perception of cues and preparation for the target. Moreover, executive control-related P3 and sustained potential (SP) differences between incongruent and congruent trials were greater in the threat versus safe state, indicating that the induced anxiety might improve the attentional allocation efficiency and stimulate subjects to recruit more cognitive resources to resolve conflicts. However, orienting-related ERPs were not affected by the threat of shock, but the threat of shock promoted the processing efficiency of spatial-cue at the behavioral level. Analysis of individual differences revealed that trait anxiety moderated the attentional allocation efficiency when performing executive control related tasks in the threat versus safe state. Our findings demonstrate the adaptive significance of the threat of shock-induced anxiety in that being in an anxious state can enhance individuals' alerting, orienting, and executive functions.

Pre-Treatment Breast Cancer Patients Show Neural Differences in Frontal Alpha Asymmetry.

Cognitive impairment has been observed consistently in a subset of breast cancer survivors. Yet, still unknown is whether neural and behavioral effects of cancer exist prior to treatment, which may contribute to later cognitive decline. The current study investigated pre-treatment differences in attention performance and frontal alpha asymmetry (FAA), an established neural index of inhibitory control, in non-metastatic breast cancer patients (n = 42) compared with healthy controls (n = 28). We additionally investigated whether differences between groups appear in specific cuing conditions and across different stages of information processing. Participants underwent EEG while completing the Attention Network Task (ANT), a cognitive measure of alerting, orienting, and inhibitory control of attention. Results revealed no behavioral differences between patients and controls but significantly greater right-hemisphere alpha activity (reduced inhibitory control) in patients, particularly to uninformative (no cue, double cue) versus informative (valid cue) cues and in later stages of information processing (400-800 ms post-stimulus). Results suggest neural differences between groups to uncertain stimulus environments that have yet to manifest behaviorally. FAA may thus serve as a unique neural correlate that could potentially be used to predict later cognitive decline.

Spatial inhibition of return is impaired in mild cognitive impairment and mild Alzheimer's disease.

Spatial inhibition of return (IOR) refers to the phenomenon by which individuals are slower to respond to stimuli appearing at a previously cued location compared to un-cued locations. Here with a group of older adults (n = 56, 58–80 (67.9±5.2) year old, 31 females, 18.7±3.6 years of education), we provide evidence supporting the notion that spatial IOR is mildly impaired in individuals with mild cognitive impairment (MCI) or mild Alzheimer’s disease (AD), and the impairment is detectable using a double cue paradigm. Furthermore, reduced spatial IOR in high-risk healthy older individuals is associated with reduced memory and other neurocognitive task performance, suggesting that the double cue spatial IOR paradigm may be useful in detecting MCI and early AD.

Should we pay attention to eye movements? The impact of bilateral eye movements on behavioral and neural responses during the Attention Network Test

Bilateral eye movements (EMs) have been associated with enhancements in episodic memory and creativity. We explored the influence of EMs on behavior and event related potential (ERP) responses during the Attention Network Test (ANT). Participants completed ANT trials after bilateral EMs or a center-fixation control manipulation. We examined condition (EM, control) and handedness (consistent, inconsistent) differences for overall task performance, as well as alerting, orienting, and executive attention networks. Behaviorally, there was a trend for inconsistent-handed participants to display faster RTs across cue types, and greater accuracy for no cue, double, and center cue trials when compared to consistent handers, yet consistent handers garnered greater improvements in behavior following altering and orienting cues than inconsistent handers. Although there were no behavioral differences between EM and control conditions, target-locked N100 and P200 ERPs were weaker in the EM than control condition for all cue types, except spatial cues for which there were no differences between groups. Because stronger N100 and P200 responses have been linked to increased selective attention, we speculate that ERP differences between EM and control conditions, in the absence of behavioral differences, may indicate that participants exposed to EMs required less selective attention to successfully complete the task.

Cognitive Performance in Indian School-Going Adolescents Is Positively Affected by Consumption of Iron-Biofortified Pearl Millet: A 6-Month Randomized Controlled Efficacy Trial

BackgroundIron deficiency remains the most prevalent micronutrient deficiency globally, but few studies have examined how iron status relates to cognition in adolescents. Iron biofortification of staple food crops is being scaled up, yet it is unknown whether consuming biofortified crops can benefit cognition. ObjectiveOur objective was to determine the efficacy of iron-biofortified pearl millet in improving attention and memory in Indian school-going adolescents. MethodsA double-blind, randomized, intervention study was conducted in 140 Indian boys and girls, aged 12–16 y, who were assigned to consume iron-biofortified [Fe = 86 parts per million (ppm)] or conventional (Fe = 21–52 ppm) pearl millet. Hemoglobin, ferritin, and transferrin receptor (TfR) were measured and body iron (BI) was calculated at baseline and after 4 and 6 mo. Five measures of cognitive function were obtained at baseline and 6 mo: simple reaction time (SRT), Go/No-Go (GNG) task, Attentional Network Task (ANT), Composite Face Effect (CFE) task, and Cued Recognition Task (CRT). Intention-to-treat analysis was used. ResultsDaily iron intake from pearl millet was higher in those consuming biofortified compared with conventional pearl millet (19.6 compared with 4.8 mg/d). Effects on ferritin, TfR, and BI at 4 mo, and on TfR at 6 mo (all P < 0.05), indicated efficacy of biofortified pearl millet over conventional pearl millet in improving iron status. Compared with conventional pearl millet, the consumption of biofortified pearl millet resulted in greater improvement in attention (SRT, GNG, and ANT) and memory (CFE and CRT). Reaction time decreased twice as much from 0 to 6 mo in those consuming biofortified compared with conventional pearl millet on attention tasks (SRT: −123 compared with −63 ms; GNG: −67 compared with −30 ms; ANT double cue: −74 compared with −32 ms; all P < 0.01). ConclusionsConsuming iron-biofortified pearl millet improves iron status and some measures of cognitive performance in Indian adolescents. This trial was registered at http://www.clinicaltrials.gov as NCT02152150.

Staying Alert? Neural Correlates of the Association Between Grit and Attention Networks.

Recent research has demonstrated that heightened motivational levels promote enhanced attention capabilities. However, the relation between attentional systems and the trait-based ability to sustain a motivational state long-term is less understood. Grit refers to one’s ability and willingness to pursue long-term goals despite setbacks. This report presents the results of two studies conducted to examine the relation between facets of Grit–Consistency and Perseverance and attention networks, assessed using the Attention Network Test (ANT). Across both studies Grit–Perseverance was related to performance on the ANT. In Study 1, Grit–Perseverance was negatively related to alerting indicating that individuals who were high on Perseverance were more likely to show a smaller alerting effect. In particular, Grit–Perseverance was negatively correlated with reaction times in the no cue trials. In Study 2, we assessed ERP components associated with attention networks. Individuals with higher scores on Grit–Perseverance were more likely to demonstrate smaller mean difference in N1 amplitudes for double cue relative to no cue trials, suggesting an attenuated alerting effect. Our findings indicate that individuals high on Grit–Perseverance may have enhanced sustained attention. Specifically individuals with high Grit–Perseverance appear to exhibit a more efficient alerting system in the no cue trials. Implications of high levels of Grit on cognitive performance are discussed.

Mind Wandering and Task-Focused Attention: ERP Correlates

Previous studies looking at how Mind Wandering (MW) impacts performance in distinct Focused Attention (FA) systems, using the Attention Network Task (ANT), showed that the presence of pure MW thoughts did not impact the overall performance of ANT (alert, orienting and conflict) performance. However, it still remains unclear if the lack of interference of MW in the ANT, reported at the behavioral level, has a neurophysiological correspondence. We hypothesize that a distinct cortical processing may be required to meet attentional demands during MW. The objective of the present study was to test if, given similar levels of ANT performance, individuals predominantly focusing on MW or FA show distinct cortical processing. Thirty-three healthy participants underwent an EEG high-density acquisition while they were performing the ANT. MW was assessed following the ANT using an adapted version of the Resting State Questionnaire (ReSQ). The following ERP’s were analyzed: pN1, pP1, P1, N1, pN, and P3. At the behavioral level, participants were slower and less accurate when responding to incongruent than to congruent targets (conflict effect), benefiting from the presentation of the double (alerting effect) and spatial (orienting effect) cues. Consistent with the behavioral data, ERP’s waves were discriminative of distinct attentional effects. However, these results remained true irrespective of the MW condition, suggesting that MW imposed no additional cortical demand in alert, orienting, and conflict attention tasks.

Does facilitation by phonological cuing in picture naming depend on the modality of the cue?

ABSTRACTBackground: Phonological cuing in spoken picture naming is widely used to improve word production accuracy in aphasic participants and to investigate word planning processes in psycholinguistic experiments with healthy participants. However, different paradigms and different modalities have been used across studies and populations, with some contradictory results.Aims: Here, we investigate whether and how the modality in which a phonological cue is delivered impacts on word production in picture naming tasks using the exact same paradigm with healthy and with aphasic participants.Methods & Procedure: In experiment 1, behavioural and electroencephalographic event-related potential (ERP) responses to auditory, visual and audiovisual cues in a picture naming task were investigated in healthy participants. In experiment 2, the impact of the same cue modalities was studied on errors and latencies in 15 aphasic participants.Outcomes & Results: The modality in which the cue is delivered influenced phonological facilitation effects in both populations, the audio modality being the most facilitative on production latencies in healthy participants and in participants with mild aphasia. No further gains were obtained by a double modality audiovisual cue on production latencies, whereas the double cues interfered with production accuracy in aphasic participants. ERP results not only were compatible with facilitation of phonological encoding in all experimental conditions but also showed modulation of a late encoding time period for both the visual and audiovisual cues, likely reflecting interference of the visual modality during monitoring or motor speech encoding. The latter observation is indeed coherent with the interference of the audiovisual modality that was observed on error rates in the more severely impaired aphasic participants.Conclusions: These results suggest that unimodal auditory cuing is the facilitatory condition, while visual cues in unimodal or bimodal conditions give rise to both facilitation and interference which manifest behaviourally depending on the balance of these opposing effects.

The alertness level influences post-error adjustments

Post-error adjustment indicates that individuals execute a chain of adjustments after committing errors to reduce the likelihood of repeating an error, which is important for our survival and evolution. It includes post-error slowing (PES), post-error improvement in accuracy (PIA), and post-error reduction of interference (PERI) three types. However, there are still intensive disputes about the generation mechanisms of the post-error adjustment. The cognitive control account suggests that errors are associated with the error monitoring and a subsequent intensification of top-down control. After committing an error, the error signal will initiate cognitive control mechanisms to improve subsequent performance by activating the anterior cingulate cortex. In this case, increased cognitive control enables flexible recruitment of attentional resources to the goal-related dimension in the subsequent task. However, the orienting account assumes that the infrequent events can easily capture the attentional resources, and thus participants need to take more time to reorient the subsequent task. The remaining resources will be insufficient to perform effectively the subsequent task, behaving as decreased post-error accuracy. Therefore, how the attention influences the post-error adjustment remains unclear. To address the above issue, we first employed an attention network test (ANT) to evaluate the attention function of each participant. The ANT task was developed to measure the efficiency of the attentional networks including alerting, orienting and executive control through a simple cue (asterisk) and arrow Flanker task. There were four cue conditions: no cue, center cue, double cue, and spatial cue. In the no cue condition, only the fixation cross was presented in the center of the screen. In the center cue condition, an asterisk was presented in the center of the screen. In the double cue and spatial cue conditions, the fixation cross was always presented in the center of the screen. However, for the double cue condition, two asterisks were presented simultaneously at two possible target positions; for the spatial cue condition, an asterisk was presented at the target position. Additionally, the efficiency of alerting was defined as RT no cue– RT double cue, the efficiency of orienting was defined as RT center cue– RT spatial cue, and the efficiency of executive control was defined as RT incongruent– RT congruent. Then, we employed a letter Flanker task to examine the participants’ performance in the post-error trials. PES was calculated by the RT of correct trials following errors minus the RT of correct trials following correct responses. PIA was calculated by the accuracy following errors minus the accuracy following correct response. And PERI was calculated by the interference magnitude ( RT incongruent– RT congruent) following correct responses minus the interference magnitude following errors. To investigate which function of the attentional network influences the post-error adjustment, we correlated the scores of alerting, orienting and executive control with PES, PIA, and PERI, respectively. Finally, based on the correlation result, we grouped the participants as high altering level group (32% participants) and low alerting level group (32% participants) to further examine the individual difference in the post-error adjustment. As a result, we found that only the alerting score was negatively correlated with PES and PIA. Moreover, in the individual difference analysis, we found that the PES was only observed in the low alerting level group, but this effect was absent in the high alerting level group. For the PIA, there was no significant difference between two groups. These results may suggest that the alerting function plays an important role in the post-error adjustments, especially for the PES. High alerting level group has an advantage on enhanced alertness; they accordingly complete post-error adjustment with high efficiency.

Alteration of the alertness-related network in patients with right temporal lobe epilepsy: A resting state fMRI study

ObjectivesThis study aimed to investigate alterations in the alertness-related network in patients with right temporal lobe epilepsy (rTLE) and explore the functional mechanisms of impaired alertness. MethodsWe recruited twenty patients with rTLE and eighteen matched healthy controls. All participants took a neuropsychological attention network test (ANT) and underwent resting-state functional magnetic resonance imaging (rs-fMRI) scanning. We extracted the alertness-related network using multiple independent component analysis (MICA). Subsequently, we compared the intergroup differences in functional connectivity (FC) of this network. Then, the neuropsychological data were correlated to voxels that showed significant FC differences in patients and controls. ResultsThe alertness-related network extracted from the patients was similar to that of the controls, covering the right dorsolateral prefrontal cortex, middle frontal gyrus, parietal lobe, part of the temporal lobe, and left posterior lobe of the cerebellum (p<0.05). Compared to controls, patients with rTLE exhibited decreased FC values in the right inferior parietal lobe (IPL) and angular gyrus (p<0.05). Additionally, increased FC was shown in the right inferior frontal gyrus, Rolandic operculum, middle frontal gyrus, dorsolateral superior frontal gyrus, cuneus, and superior occipital gyrus (p<0.05). Behaviorally, patients with rTLE exhibited longer reaction times (RT) in the no cue (t=−2.07, p<0.05) and double cue (t=−2.28, p<0.05) conditions. However, the alertness effect in patients did not significantly differ from that of controls. Moreover, the alertness effect was negatively correlated with the mean Z-value in the right cuneus, which showed increased FC (r=−0.556, p=0.013) in patients with rTLE. There was no significant correlation in the control group. ConclusionOur results demonstrated that alterations in the alertness-related network may contribute to the alertness impairment exhibited by patients with rTLE. Our study may provide new insights into the mechanisms of alertness impairments in rTLE.

Eccentricity Effects on the Efficiency of Attentional Networks: Evidence From a Modified Attention Network Test.

The effects of eccentricity on the attentional modulation of visual discrimination have been widely studied; however, the substrate of this complex phenomenon is poorly understood. Here, we provided a measure of the effects of eccentricity on three attentional networks: alerting, orienting, and executive attention. Participants ( N = 63) were tested with a modified attention network test that included an additional eccentricity variation; this test allowed us to investigate the efficiency of the attentional networks at near and far eccentricities. Compared with targets at the near eccentricity, targets at the far eccentricity generally elicited significantly longer reaction times. We also found the far eccentricity was associated with smaller orienting effect scores and larger executive control scores than the near eccentricity. Interestingly, at the near eccentricity, executive control scores were larger when the spatial information was neutral (no cue, center cue, and double cue), but at the far eccentricity, the scores were larger when the spatial information was valid (spatial cue). We propose that the allocation of attentional resources differed among these cue conditions and influenced the interference caused by conflicting information.

Revisiting the global effect and inhibition of return

Saccades toward previously cued locations have longer latencies than saccades toward other locations, a phenomenon known as inhibition of return (IOR). Watanabe (Exp Brain Res 138:330–342. doi:10.1007/s002210100709, 2001) combined IOR with the global effect (where saccade landing points fall in between neighboring objects) to investigate whether IOR can also have a spatial component. When one of two neighboring targets was cued, there was a clear bias away from the cued location. In a condition where both targets were cued, it appeared that the global effect magnitude was similar to the condition without any cues. However, as the latencies in the double cue condition were shorter compared to the no cue condition, it is still an open question whether these results are representative for IOR. Considering the double cue condition can provide valuable insight into the interaction of the mechanisms underlying the two phenomena, here, we revisit this condition in an adapted paradigm. Our paradigm does result in longer latencies for the cued locations, and we find that the magnitude of the global effect is reduced significantly. Unexpectedly, this holds even when only including saccades with the same latencies for both conditions. Thus, the increased latencies associated with IOR cannot directly explain the reduction in global effect. The global effect reduction can likely best be seen as either a result of short-term depression of exogenous visual signals or a result of IOR established at the center of gravity of cues.Electronic supplementary materialThe online version of this article (doi:10.1007/s00221-016-4702-9) contains supplementary material, which is available to authorized users.

Follow your nose: leaf odour as an important foraging cue for mammalian herbivores.

Studies of odour-driven foraging by mammals focus on attractant cues emitted by flowers, fruits, and fungi. Yet, the leaves of many plant species worldwide produce odour, which could act as a cue for foraging mammalian herbivores. Leaf odour may thus improve foraging efficiency for such herbivores in many ecosystems by reducing search time, particularly but not only, for plants that are visually obscured. We tested the use of leaf odour by a free-ranging mammalian browser, the swamp wallaby (Wallabia bicolor) to find and browse palatable tree seedlings (Eucalyptus pilularis). Wallabies visited patches non-randomly with respect to the presence of seedlings. In the absence of visual plant cues, they used leaf odour (cut seedlings in vials) to find patches earlier, and visited and investigated them more often than control patches (empty vials), supporting the hypothesis that wallabies used seedling odour to enhance search efficiency. In contrast, the grey kangaroo (Macropus giganteus), a grazer, showed no response to seedling odour. When the availability of seedling visual and olfactory cues was manipulated, wallabies browsed seedlings equally quickly in all treatments: upright (normal cues), pinned to the ground (reduced visual cues), and upright plus pinned seedlings (double olfactory cues). Odour cues play a critical role in food-finding by swamp wallabies, and these animals are finely tuned to detecting these cues with their threshold for detection reached by odours from only a single plant. The global significance of leaf odour in foraging by mammalian herbivores consuming conifers, eucalypts, and other odour-rich species requires greater attention.

Cue combination anisotropies in contour integration: The role of lower spatial frequencies.

The combination of local orientation collinearity and spatial frequency contrast in contour integration was studied in two experiments using a 2AFC contour detection and discrimination task. Target contours were defined by local orientation collinearity, spatial frequency contrast between contour and background elements, or both cues. Experiments differed in the source of spatial frequency contrast by manipulating the spatial frequency of either contour or background elements. Cue summation gains, defined as the performance benefit of double cue conditions over single cue conditions, were evaluated and tested against the predictions derived from probability summation and linear summation. Summation gains were generally stronger than linear summation and tended to increase with the single-cue performance level until limited by ceiling effects. Cue summation was particularly large when contour elements exhibited a lower spatial frequency than background elements, regardless of the absolute spatial frequency ranges. The highly effective integration of lower spatial frequency contours in cluttered surrounds is discussed in the context of recent findings on high-level neural representations of contour integration as well as feature synergy.

Modality and task switching interactions using bi-modal and bivalent stimuli

Investigations of concurrent task and modality switching effects have to date been studied under conditions of uni-modal stimulus presentation. As such, it is difficult to directly compare resultant task and modality switching effects, as the stimuli afford both tasks on each trial, but only one modality. The current study investigated task and modality switching using bi-modal and bivalent stimulus presentation under various cue conditions: no cue, either task or modality (single cue) or task and modality (double cue), with participants responding to either the identity or the position of an audio–visual stimulus at each trial. In line with previous research, task and modality switching effects showed sub-additive patterns, with switching costs decreasing as pre-stimulus cue information increased. The current data also showed that modality switching costs were more malleable than task switching costs as the former were eliminated when full and single cue information was provided, as well as when participants responded to the more efficiently processed task (position relative to identity). Conversely, task switching costs were only eliminated in the full cue condition, but were present for both tasks and both modalities despite a similar asymmetry in efficiency (vision relative to audition). The data further show that the specific task-modality combination being responded to impacted on combined task- and modality switching effects, with those combinations leading to either the greatest or lowest costs contributing most heavily to sub-additivity.

A unitary focus of spatial attention during attentional capture: Evidence from event-related brain potentials

We studied whether attentional capture in vision can be elicited simultaneously at multiple locations in the visual field or whether it is always restricted to a single location. Participants searched for color singleton targets in search arrays that were preceded by spatially uninformative color cue arrays. Single cue arrays contained a unique color singleton among gray background items, and double cue arrays included two different-colored objects. Behavioral spatial cueing effects and N2pc components indicative of attentional capture were triggered by single as well as double cue arrays, but these capture effects were smaller with double cues. Response latencies were used to distinguish double cue trials where attention was captured by a left or right cue and trials where it was attracted by a cue on the vertical meridian. The N2pc was only present on horizontal capture trials, indicating that attentional capture is not triggered in parallel and equally at different locations, but is strongly weighted towards one object and one location at a time. Results show that when multiple salient visual objects compete for attentional selection, the capacity of each object to capture attention is reduced, but the focus of spatial attention tends to remain unitary.

Spatial orienting of attention simultaneously cued by automatic social and nonsocial cues

The appearance of a stimulus in the periphery and the direction of another person's eye gaze have both been shown to automatically orient attention toward the stimulus and the gazed-at location, respectively. In the present experiment, we examined the effects of viewing both a peripheral stimulus and an eye gaze stimulus simultaneously in order to determine whether one is "more automatic" (i.e., faster, dominates) than the other and whether the two processes interact. Using a spatial cueing paradigm, we measured latency of localization of a target stimulus that was validly or invalidly cued by an uninformative (i.e., nonpredictive) peripheral cue, an uninformative eye gaze cue, or both simultaneously (double cue). We included a short and a long cue-target interval in order to investigate the early and late facilitatory and inhibitory effects of the two processes. Results demonstrated that when the double cues were consistent with each other (indicating the same target location), the effects, both early and late, were the same as when the peripheral cue was presented alone. When the double cues were inconsistent (indicating opposite target locations), the late effect was the same as the peripheral cue, but the early effect was intermediate between the two types of cues. Our results better support an interactive, rather than an additive relationship between social and nonsocial automatic orienting. The double cue conditions that showed similar effects to the peripheral cues suggest that the peripheral cue dominates.

Investigating task and modality switching costs using bimodal stimuli

Investigations of concurrent task and modality switching effects have to date been studied under conditions of uni-modal stimulus presentation. As such, it is difficult to directly compare resultant task and modality switching effects, as the stimuli afford both tasks on each trial, but only one modality. The current study investigated task and modality switching using bi-modal stimulus presentation under various cue conditions: task and modality (double cue), either task or modality (single cue) or no cue. Participants responded to either the identity or the position of an audio–visual stimulus. Switching effects were defined as staying within a modality/task (repetition) or switching into a modality/task (change) from trial n − 1 to trial n, with analysis performed on trial n data. While task and modality switching costs were sub-additive across all conditions replicating previous data, modality switching effects were dependent on the modality being attended, and task switching effects were dependent on the task being performed. Specifically, visual responding and position responding revealed significant costs associated with modality and task switching, while auditory responding and identity responding revealed significant gains associated with modality and task switching. The effects interacted further, revealing that costs and gains associated with task and modality switching varying with the specific combination of modality and task type. The current study reconciles previous data by suggesting that efficiently processed modality/task information benefits from repetition while less efficiently processed information benefits from change due to less interference of preferred processing across consecutive trials.

Preattentional processes and disorganization in schizophrenia: Influence of a 6-week risperidone treatment

Introduction Visual orientation and attention are impaired in schizophrenia. Engagement and disengagement of attention and the ability to prompt responses to a stimulus in patients before and after six weeks of risperidone were compared to controls. Methods Ten unmedicated (nine naïve) schizophrenic patients, and eleven controls performed 1) A visual orienting task, the Cued Target Detection task (CTD), with the detection of a visual stimulus in valid, invalid, no cue and double cue trials, two conditions for fixation offset for a modulation of visual fixation: Gap: 200 ms before target; No Gap: simultaneous with target, 2) Choice Reaction Time (CRT 0.5 and 2 s delays). Results At baseline, patients showed longer RT than controls in CRT, but not in CTD, with in CTD, no facilitation of RT with the gap procedure. The alertness index was almost null in CTD-Gap and comparable to controls in CTD-No Gap. Efficiency to detect attended stimuli (CTD-No Gap) and warning effect (CRT 0.5 s) were negatively correlated to disorganization. After treatment, readiness to act in CRT had decreased. In CTD-No Gap, change in PANSS disorganization was correlated to an increased validity index, change in negative sub-score was correlated to decreased attention cost. Conclusion Untreated patients displayed a deficit of Gap effect and a slowing in sustained attention. Disorganization interfered with warning and visual detection. After treatment, its improvement and negative symptoms improvement were associated with better visual detection. These alterations in visual orienting provide new evidence for an oculomotor dysregulation of attentional engagement in schizophrenia.