Serial Search Task Research Articles

Visual statistical learning requires attention.

Statistical learning is a person's ability to automatically learn environmental regularities through passive exposure. Since the earliest studies of statistical learning in infants, it has been debated exactly how "passive" this learning can be (i.e., whether attention is needed for learning to occur). In Experiment 1 of the current study, participants performed a serial feature search task where they searched for a target shape among heterogenous nontarget shapes. Unbeknownst to the participants, one of these nontarget shapes was presented much more often in location. Even though the regularity concerned a nonsalient, nontarget item that did not receive any attentional priority during search, participants still learned its regularity (responding faster when it was presented at this high-probability location). While this may suggest that not much, if any, attention is needed for learning to occur, follow-up experiments showed that if an attentional strategy (i.e., color subset search or exogenous cueing) effectively prevents attention from being directed to this critical regularity, incidental learning is no longer observed. We conclude that some degree of attention to a regularity is needed for visual statistical learning to occur.

Fixating targets in visual search: The role of dorsal and ventral attention networks in the processing of relevance and rarity

Abstract The dorsal attention network, often observed to be activated in serial visual search tasks, has been associated with goal-directed attention, responsible for the processing of task relevance. In serial visual search, the moment of target detection constitutes not only a task-relevant event, but also a rare event. In the present fMRI experiment, we disentangled task relevance from item rarity using a fixation-based analysis approach. We used a multiple target search task, and participants had to report the number of targets among distractors in the display. We had also added rare distractors to the displays. We found that rare events (targets and rare distractors) activated the dorsal attention network more strongly than common distractors. More importantly, we observed that the left IPS and the left insula, belonging to the dorsal and ventral attention system, respectively, were more strongly activated for targets compared to rare distractors. Using multi-voxel pattern analysis, we found that activation in the TPJ, bilaterally, an area also associated with the ventral attention system, distinguished between target and rare distractor fixations. These results point to an expanded role of the TPJ that seems to process post-perceptual information which is linked to task relevance.

Impaired Ability in Visual-Spatial Attention in Chinese Children With Developmental Dyslexia.

A growing body of evidence suggests that children with dyslexia in alphabetic languages exhibit visual-spatial attention deficits that can obstruct reading acquisition by impairing their phonological decoding skills. However, it remains an open question whether these visual-spatial attention deficits are present in children with dyslexia in non-alphabetic languages. Chinese, with its logographic writing system, offers a unique opportunity to explore this question. The presence of visual-spatial attention deficits in Chinese children with dyslexia remains insufficiently investigated. Therefore, this study aimed to explore whether such deficits exist, employing a visual search paradigm. Three visual search tasks were conducted, encompassing two singleton feature search tasks and a serial conjunction search task. The results indicated that Chinese children with dyslexia performed as well as chronological age-matched control children in color search tasks but less effectively in orientation search, suggesting a difficulty in the rapid visual processing of orientation: a deficit potentially specific to Chinese dyslexia. Crucially, Chinese children with dyslexia also exhibited lower accuracy, longer reaction times, and steeper slopes in the reaction times by set size function in the conjunction search task compared to control children, which is indicative of a visual-spatial attention deficit.

Reduced spatial attentional distribution in older adults.

Older adults show decline in visual search performance, but the underlying cause remains unclear. It has been suggested that older adults' altered performance may be related to reduced spatial attention to peripheral visual information compared with younger adults. In this study, 18 younger (M = 21.6 years) and 16 older (M = 69.1 years) participants performed pop-out and serial visual search tasks with variously sized gaze-contingent artificial central scotomas (3°, 5°, or 7° diameter). By occluding central vision, we measured how attention to the periphery was contributing to the search performance. We also tested the effect of target eccentricity on search times and eye movements. We hypothesized that, if attention is reduced primarily in the periphery in older adults, we would observe longer search times for more eccentric targets and with central occlusion. During the pop-out search, older adults showed a steeper decline in search performance with increasing eccentricity and central scotoma size compared with younger adults. In contrast, during the serial search, older adults had longer search times than younger adults overall, independent of target eccentricity and scotoma size. Longer search times were attributed to higher cost-per-item slopes, indicating increased difficulty in simultaneously processing complex symbols made up of separable features in aging, possibly stemming from challenges in spatially binding individual features. Altogether, our findings point to fewer attentional resources of simultaneous visual processing to distribute over space or separable features of objects, consistent with decreased dorsal visual stream functioning in aging.

Is attention necessary for the representational advantage of good exemplars over bad exemplars?

Real-world (rw-) statistical regularities, or expectations about the visual world learned over a lifetime, have been found to be associated with scene perception efficiency. For example, good (i.e., highly representative) exemplars of basic scene categories, one example of an rw-statistical regularity, are detected more readily than bad exemplars of the category. Similarly, good exemplars achieve higher multivariate pattern analysis (MVPA) classification accuracy than bad exemplars in scene-responsive regions of interest, particularly in the parahippocampal place area (PPA). However, it is unclear whether the good exemplar advantages observed depend on or are even confounded by selective attention. Here, we ask whether the observed neural advantage of the good scene exemplars requires full attention. We used a dual-task paradigm to manipulate attention and exemplar representativeness while recording neural responses with functional magnetic resonance imaging (fMRI). Both univariate analysis and MVPA were adopted to examine the effect of representativeness. In the attend-to-scenes condition, our results replicated an earlier study showing that good exemplars evoke less activity but a clearer category representation than bad exemplars. Importantly, similar advantages of the good exemplars were also observed when participants were distracted by a serial visual search task demanding a high attention load. In addition, cross-decoding between attended and distracted representations revealed that attention resulted in a quantitative (increased activation) rather than qualitative (altered activity patterns) improvement of the category representation, particularly for good exemplars. We, therefore, conclude that the effect of category representativeness on neural representations does not require full attention.

Characteristics of Visual Cognition in Patients with Anoxic Encephalopathy: An Eye-tracking Study.

: Despite the frequent occurrence of visual cognitive impairment after anoxic encephalopathy, only a few studies have analyzed gaze movements following encephalopathy. This study determined the visual cognitive characteristics of patients with anoxic encephalopathy using an eye-tracking system. : This study included ten patients with anoxic encephalopathy and ten age/sex-matched controls. Factors for anoxic encephalopathy onset and brain imaging findings were extracted from medical records. An eye-tracking system was used to track eye movements during three visual search tasks (pop-out, serial search, and saliency) in patient and healthy control groups. The average target search time, number of saccades, and number of fixations to salient stimuli were compared. : Stagnant blood flow, observed in six of ten patients, was the most common cause of disease onset, four of whom exhibited hypoperfusion in bilateral occipital or parietal lobes on single-photon emission computed tomography. The patient group required longer search times during all visual search tasks and a higher number of saccades during pop-out and serial search tasks. However, no significant difference was observed between the two groups for the number of fixations to salient stimuli during the saliency task. : Following anoxic encephalopathy, bottom-up (pop-out task) and top-down (serial search task) gaze control were considered impaired because of extensive parieto-occipital lobe damage after blood flow stagnation. Patients exhibited reduced top-down function for finding targets (serial search task) but relatively retain inhibitory function for salient stimuli (saliency task). Gaze analysis can be used to reveal the clinical characteristics of anoxic encephalopathy.

EEG cortical network reveals the temporo-spatial mechanism of visual search

This study aims to explore a method based on brain networks for implicit attention by using wavelet coherence as feature to identify individual targets in the visual field, find the optimal classification rhythm and time window, and investigate the relationship between the optimal rhythm and N2pc event-related potential. The study uses a weighted minimum norm estimate to locate the sources of the scalp EEG and reconstructs the source time series. The functional connectivity between brain areas during the visual search process is evaluated using wavelet coherence analysis, and a lateral difference network is constructed based on the difference in coherence values between the left and right visual fields. A support vector machine classifier is trained based on the wavelet coherence network features to identify the target in the left or right visual field. We also extract N2pc from the source activity data of the parieto-occipital brain region and record the time period in which N2pc occurred. The study finds that the best classification performance is achieved in the theta rhythm from 200 to 400 ms and achieved an average classification accuracy of 87% (chance level: 51.07%) in a serial search task. And this time window corresponds to the time period when N2pc appeared. The results show that the use of wavelet coherence analysis to evaluate the functional connectivity between brain areas during the visual search process provides a new approach for analyzing brain activity. The study's findings regarding the relationship between the N2pc and theta rhythm and the effectiveness of using wavelet coherence network features based on the theta rhythm for visual search classification contribute to the understanding of the neural mechanisms underlying visual search.

Early detection of cognitive decline in Alzheimer's disease using eye tracking.

Patients with Alzheimer's disease (AD) are known to exhibit visuospatial processing impairment, as reflected in eye movements from the early stages of the disease. We investigated whether the pattern of gaze exploration during visual tasks could be useful for detecting cognitive decline at the earliest stage. Sixteen AD patients (age: 79.1 ± 7.9 years, Mini Mental State Examination [MMSE] score: 17.7 ± 5.3, mean ± standard deviation) and 16 control subjects (age: 79.4 ± 4.6, MMSE score: 26.9 ± 2.4) participated. In the visual memory task, subjects memorized presented line drawings for later recall. In the visual search tasks, they searched for a target Landolt ring of specific orientation (serial search task) or color (pop-out task) embedded among arrays of distractors. Using video-oculography, saccade parameters, patterns of gaze exploration, and pupil size change during task performance were recorded and compared between AD and control subjects. In the visual memory task, the number of informative regions of interest (ROIs) fixated was significantly reduced in AD patients compared to control subjects. In the visual search task, AD patients took a significantly longer time and more saccades to detect the target in the serial but not in pop-out search. In both tasks, there was no significant difference in the saccade frequency and amplitude between groups. On-task pupil modulation during the serial search task was decreased in AD. The number of ROIs fixated in the visual memory task and search time and saccade numbers in the serial search task differentiated both groups of subjects with high sensitivity, whereas saccade parameters of pupil size modulation were effective in confirming normal cognition from cognitive decline with high specificity. Reduced fixation on informative ROIs reflected impaired attentional allocation. Increased search time and saccade numbers in the visual search task indicated inefficient visual processing. Decreased on-task pupil size during visual search suggested decreased pupil modulation with cognitive load in AD patients, reflecting impaired function of the locus coeruleus. When patients perform the combination of these tasks to visualize multiple aspects of visuospatial processing, cognitive decline can be detected at an early stage with high sensitivity and specificity and its progression be evaluated.

Developing a Serial Search Task to Evaluate Procedural Memory and Investigating the Relationship Between Procedural Memory and Grammar in Farsi-speaking Children: A Preliminary Study

Objective: Procedural memory is a key component of long-term memory that can be assessed in different modalities, such as verbal and motor. Learning through procedural memory occurs in three stages: initial learning, consolidation, and retention. Several tasks evaluate procedural memory, but none have concurrently studied procedural learning in various modalities and learning stages. Besides, according to the declarative-procedural model, there may be an association between the performance of individuals in procedural learning and their state of the grammar of a language. Therefore, this study aimed to design a Serial Search Task (SST) for the simultaneous evaluation of procedural memory in motor and verbal modalities during three stages of learning and determine its reliability. Moreover, the relationship between procedural memory and grammar skills was examined. Materials & Methods: This study is methodological research in the first stage and descriptive analytics in the second stage. First, based on the literature review and the opinions of three speech-language pathologists, some words with appropriate psycholinguistic features were chosen from the Persian picture naming set. Then, corresponding pictures were determined. The task was designed using Java programming language. The face validity of the task was evaluated, then after revisions, the reliability was determined. Face validity was assessed in 10 normal children, and the test-retest reliability was evaluated in 15 normal children aged 7-9 years; all of them were chosen using the convenience sampling method. In the second stage, to assess the relationship between grammatical skills and the SST, 20 normal children aged 7-9 years were selected by a mixed sampling method. Every child had exposed to a verbal modality in three stages: initial learning, consolidation (24 hours later), and retention (one week later). Then the same stages were performed in the motor modality. Each child's language skills were determined using the test of language development-primary (TOLD-P3), and the relationship between the two skills was determined. Statistical methods included the Pearson and Spearman correlation coefficients and repeated measures analysis of variance. Results: The correlation values between two performances in the initial learning stage for the reaction time variable in verbal (r=0.84, P<0.001) and motor (r=0.80, P˂0.001) modalities and the variable of response accuracy in verbal (r=0.81, P=0.011) and motor (r=0.77, P=0.026) modalities were obtained. In the consolidation and retention stages, the correlation values for the reaction time variable in verbal (r=0.737, P=0.002) and motor (r=0.743, P=0.001) modalities and the variable of response accuracy in verbal (r=0.624, P=0.013) and motor (r=0.916, P<0.001) modalities were obtained. The relationship between grammar and procedural learning in the verbal modality was significant in the consolidation stage (P=0.045, CI:0.016-0.797, r=0.491). Conclusion: SST is a reliable task to assess different stages of procedural memory in both verbal and motor modalities. Therefore, this task can be used to evaluate procedural memory in normal children aged 7-9 years. The current study's findings confirmed the predictions made by the declarative-procedural model during the consolidation stage in the verbal modality.

0215 Impact of sleep inertia on visual search performance during combined sleep restriction and circadian misalignment

Abstract Introduction Circadian phase and homeostatic sleep drive affect selective visual attention during sleep inertia (SI), a period of cognitive performance decrement upon awakening that dissipates with time. This study examined the combined effects of circadian misalignment and sleep restriction on visual search performance during SI. Methods Twenty adults (mean±standard deviation [SD] age 25.7±4.2 years; 12M, 8F) completed a 39-day protocol. Prior to a 4-day in-laboratory visit, participants maintained habitual 8h sleep schedules for 2 weeks at home. In-laboratory sleep opportunities (1 per day) were timed to induce varying levels of both circadian misalignment and sleep restriction: 8h on night 1, 3h on night 2, and 3h on mornings 3 and 4. After 3 days of recovery sleep at home (unscheduled), participants repeated the entire protocol. SI was assessed with the Serial Visual Search Task, a measure of selective visual attention, ~ 1, 16, and 31 min after electroencephalogram (EEG) verified awakening following each 3h sleep opportunity. The task required participants to determine whether a target was present or absent among nontarget distractors. Outcomes included median reaction times (RT) and number of missed targets. Sleep opportunities with ≥4.5 min of EEG-verified wakefulness in the 30 min prior to scheduled awakening were excluded from analysis. Data were analyzed with mixed-model ANOVA. Results Mean±SD average amount of wakefulness in the 30 min and 10 min prior to SI testing was 1.2±0.11 and 0.43±0.06 minutes, respectively. Following all sleep opportunities, median RT for overall correct responses and for correct response to target absent trials improved with time since awakening (all p<0.05). In contrast, median RT for correct responses to target present trials improved and number of missed targets worsened with time since awakening following the morning 3 sleep opportunity only (all p<0.05). Conclusion Reaction speed was impaired during SI regardless of circadian timing or level of homeostatic sleep drive, whereas missing targets appears to be dependent upon circadian phase and the level of homeostatic sleep debt. These findings have important implications for military and first responders. Support (If Any) Office of Naval Research MURI N00014-15-1-2809; NIH TR001082; Undergraduate Research Opportunities Grant, University of Colorado Boulder.

Attentional limits in visual search with and without dorsal parietal dysfunction: space-based window or object-based span?

Attentional resource and distribution are specifically impaired in simultanagnosia, and also in the visuo-attentional form of developmental dyslexia. Both clinical conditions are conceived as a limitation of simultaneous visual processing after superior parietal lobule (SPL) dysfunction (review in Valdois et al., 2019). However, a reduced space-based attentional window (i.e. a limited visual eccentricity at which the target object can be identified, Khan et al. 2016) has been demonstrated in simultanagnosia versus a reduced object-based span (i.e. a limited number of objects processed at each fixation, Bosse et al., 2007) in developmental dyslexia. In healthy individuals, the cost in reaction times per item in serial search tasks suggests that a group of objects is processed simultaneously at a time, but this group is also undefined and depends on the visual complexity of the task.Healthy individuals and a patient with simultanagnosia performed serial search tasks involving either symbols (made of separable features) or objects made of non-separable features, and with distractors that were either all identical or all dissimilar. We used a moving window paradigm to determine whether the task was performed with a “working space” versus a “working span” limitation in control group and in patient with bilateral SPL damage.We found that healthy individuals performed search in a color task comprising non-separable feature objects and dissimilar distractors with a limited space-based attentional window; this attentional window, as well as the mean saccade amplitude used to displace it across the visual display, were independent of set size, thus inconsistent with an object-based attentional span. In the symbol task comprising a feature-absent search in which all feature-present distractors were dissimilar, we observed that mean saccade amplitude decreased with set size and that search performance could not be mimicked by a moving window of a single diameter; instead participants seemed to process a fixed number of symbols at a time (object-based span).Following bilateral SPL lesions, patient IG demonstrated a similar space-based search process in the color search task with a normal attentional window. In contrast, her cost-per-item in the symbol task increased dramatically, demonstrating a clear deficit of simultaneous object perception. These results confirmed the specific contribution of the SPL to the visual processing of multiple objects made of separable features (like letters), and more dramatically when they are all different, which explains the specific difficulty for a reading beginner in case of SPL dysfunction.

Visual search in neurodevelopmental disorders: evidence towards a continuum of impairment

Disorders with neurodevelopmental aetiology such as Attention-Deficit/Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD) and Schizophrenia share commonalities at many levels of investigation despite phenotypic differences. Evidence of genetic overlap has led to the concept of a continuum of neurodevelopmental impairment along which these disorders can be positioned in aetiological, pathophysiological and developmental features. This concept requires their simultaneous comparison at different levels, which has not been accomplished so far. Given that cognitive impairments are core to the pathophysiology of these disorders, we provide for the first time differentiated head-to-head comparisons in a complex cognitive function, visual search, decomposing the task with eye movement-based process analyses. N = 103 late-adolescents with schizophrenia, ADHD, ASD and healthy controls took a serial visual search task, while their eye movements were recorded. Patients with schizophrenia presented the greatest level of impairment across different phases of search, followed by patients with ADHD, who shared with patients with schizophrenia elevated intra-subject variability in the pre-search stage. ASD was the least impaired group, but similar to schizophrenia in post-search processes and to schizophrenia and ADHD in pre-search processes and fixation duration while scanning the items. Importantly, the profiles of deviancy from controls were highly correlated between all three clinical groups, in line with the continuum idea. Findings suggest the existence of one common neurodevelopmental continuum of performance for the three disorders, while quantitative differences appear in the level of impairment. Given the relevance of cognitive impairments in these three disorders, we argue in favour of overlapping pathophysiological mechanisms.

Inefficient visual search strategies in the first-episode schizophrenia spectrum

BackgroundKnowledge is lacking regarding deficits in selective attention and their underlying biological mechanisms during early stages of schizophrenia. The present study examined the N2pc, a neurophysiological index of covert spatial attention, and its cortical sources at first psychotic episode in the schizophrenia spectrum (FESz). MethodsNeurophysiological responses measured simultaneously with magnetoencephalography (MEG) and electroencephalography (EEG) during pop-out and serial search tasks were compared between 32 FESz and 32 matched healthy controls (HC). Mean scalp-recorded N2pc was measured from a cluster of posterior-lateral EEG electrodes. Cortical source-resolved MEG activity contributing to the N2pc signal was derived for the intraparietal sulcus (IPS) and lateral occipital complex (LOC). ResultsGroup differences in EEG N2pc varied by task demand. FESz exhibited reduced N2pc amplitude during pop-out (p < .01), but not serial search (p = .11). Furthermore, group differences in N2pc-related MEG cortical activity varied by task demand and cortical region. Compared to HC, FESz exhibited greater IPS during serial search (p < .01). DiscussionReductions in EEG N2pc amplitude indicate an impairment of visuo-spatial attention evident at an individual's first psychotic episode, specifically during conditions emphasizing bottom-up processing. Examination of its cortical sources with MEG revealed that, compared to HC, FESz engaged parietal structures to a greater extent during the serial search condition. This pattern suggests a less efficient, more resource intensive strategy employed by FESz in response to a minimal demand on attention. The greater reliance on this controlled attentional network may negatively impact real-world functions with much greater complexity and attentional demands.

The nature of inhibition in a working memory search task

ABSTRACTInhibition is one of the key processes that regulate working memory (WM) activity. The main research question concerned the nature of inhibition of highlighted information in WM. The study was designed to examine two competing hypotheses. The first assumed that inhibition is carried out by deletion of irrelevant information from the focus of attention (cognitive inhibition account). An alternative hypothesis assumed that it is the response to a correctly recognised stimulus that is inhibited (effortful response inhibition account). Two experiments with a spatial modification of the WM serial search task were conducted wherein two factors were manipulated: serial order of the items, and distance from the central fixation point. In both experiments, higher response time was correlated with a smaller distance from the fixation point. The inhibited items were recognised equally efficiently or better than the uninhibited items. The results support the effortful response inhibition account over the cognitive inhibition account.

Experience-guided attention: Uniform and implicit.

Frequently finding a visual search target in one region of space induces a spatial attentional bias toward that region. Past studies on this effect typically tested fewer than 20 participants. The small sample prevents an investigation of two properties of learning: visual field uniformity and role of explicit awareness. Pooling data from multiple studies, here we examined location probability learning from ~120,000 visual search trials across 420 participants. Participants performed a serial search task. Unbeknownst to them, the target was disproportionately likely to appear in one visual quadrant. Location probability learning (LPL) was measured as the difference in reaction time to targets in the high-probability "rich" quadrant and the low-probability "sparse" quadrants. Results showed a lack of visual field effect. LPL was equivalent for "rich" quadrant in the upper left, upper right, lower left, and lower right. Learning did not induce a hotspot diagonal to the "rich" quadrant. To the contrary, RT was the longest in the diagonal quadrant. Recognition rate of the "rich" quadrant was above chance. However, recognition accuracy was unrelated to the size of LPL. Implicit learning induces visual-field-independent changes in spatial attention.

Spatiotemporal encoding of search strategies by prefrontal neurons

Working memory is capacity-limited. In everyday life we rarely notice this limitation, in part because we develop behavioral strategies that help mitigate the capacity limitation. How behavioral strategies are mediated at the neural level is unclear, but a likely locus is lateral prefrontal cortex (LPFC). Neurons in LPFC play a prominent role in working memory and have been shown to encode behavioral strategies. To examine the role of LPFC in overcoming working-memory limitations, we recorded the activity of LPFC neurons in animals trained to perform a serial self-ordered search task. This task measured the ability to prospectively plan the selection of unchosen spatial search targets while retrospectively tracking which targets were previously visited. We found that individual LPFC neurons encoded the spatial location of the current search target but also encoded the spatial location of targets up to several steps away in the search sequence. Neurons were more likely to encode prospective than retrospective targets. When subjects used a behavioral strategy of stereotyped target selection, mitigating the working-memory requirements of the task, not only did the number of selection errors decrease but there was a significant reduction in the strength of spatial encoding in LFPC. These results show that LPFC neurons have spatiotemporal mnemonic fields, in that their firing rates are modulated both by the spatial location of future selection behaviors and the temporal organization of that behavior. Furthermore, the strength of this tuning can be dynamically modulated by the demands of the task.

Current Understanding of Dyslexia and Pilot Data on Efficacy of a Mindfulness Based Psychotherapy (MBR-RAM) Model

Background: Dyslexia, a heterogeneous syndrome, is the most recognized Developmental Reading Disorder (DRD) with 5-17% prevalence and poses as a significant disability. Its core deficits are: Phonological deficits, poor visual attention span, selective deficits in complex serial visual search tasks, sustained visual attention problems, visuospatial functioning and difficult image reproduction from memory. Much remains to be accomplished clinically to address these deficits. Methods: Mindfulness Based Rehabilitation of Reading, Attention & Memory (MBR-RAM©) is a translational mindfulness based cognitive behavioral therapy developed by the first author. MBR-RAM uses focused attention enhancement visual meditation techniques (Sanskrit: trataka) in therapist-assisted and home-practice formats to rehabilitate reading deficits, visual inattention, visual motor incoordination, information processing speed and visual memory. Visual motor incoordination indicates inability to control hand movements guided by the visual cues while reading letters. Three Caucasian subjects in this study included an 8-year-old girl and two boys aged 9 and 10 years. The objectives were to study the changes pre- and post-intervention with respect to their scores on the various clinical and neuropsychological measures. Results: Compared to the baseline, all three subjects showed clinical and statistically significant improvements in the outcome measures, which were sustained for at least 6 months after study completion. There were no adverse effects in them. Conclusion: Results of this pilot study indicate that MBR-RAM© is a feasible, low cost treatment, which is effective for rehabilitating some important deficits of dyslexia. The results need replication in future studies with better methodology to make definite conclusions. Keywords: Dyslexia, learning disorder, reading disorder, yoga, mindfulness, trataka.

Lexical Access in L2 Speech Production: a controlled serial search task

When it comes to lexical access in L2 speech production, working memory (WM) seems to play a central role as for less automatized procedures require more WM capacity to be executed (Prebianca, 2007). With that in mind, this paper aims at claiming that bilingual lexical access qualifies as a controlled serial strategic search task susceptible to individual differences in WM capacity. Evidence in support of such claim is provided by the results of AUTHOR's (2010) study conducted so as to investigate the relationship between L2 lexical access, WMC and L2 proficiency. AUTHOR's (2010) findings indicate that bilingual lexical access entails underlying processes such as cue generation, set delimitation, serial search and monitoring, which to be carried out, require the allocation of attention. Attention is limited and, as a result, only higher spans were able to perform these underlying processes automatically.

Gaze Linking in Visual Search: A Help or a Hindrance?

Gaze linking allows team members in a collaborative visual task to scan separate computer monitors simultaneously while their eye movements are tracked and projected onto each other’s displays. The present study explored the benefits of gaze linking to performance in unguided and guided visual search tasks. Participants completed either an unguided or guided serial search task as both independent and gaze-linked searchers. Although it produced shorter mean response times than independent search, gaze linked search was highly inefficient, and gaze linking did not differentially affect performance in guided and unguided groups. Results suggest that gaze linking is likely to be of little value in improving applied visual search.

Implicit object naming in visual search: Evidence from phonological competition.

During visual search, people are distracted by objects that visually resemble search targets; search is impaired when targets and distractors share overlapping features. In this study, we examined whether a nonvisual form of similarity, overlapping object names, can also affect search performance. In three experiments, people searched for images of real-world objects (e.g., a beetle) among items whose names either all shared the same phonological onset (/bi/), or were phonologically varied. Participants either searched for 1 or 3 potential targets per trial, with search targets designated either visually or verbally. We examined standard visual search (Experiments 1 and 3) and a self-paced serial search task wherein participants manually rejected each distractor (Experiment 2). We hypothesized that people would maintain visual templates when searching for single targets, but would rely more on object names when searching for multiple items and when targets were verbally cued. This reliance on target names would make performance susceptible to interference from similar-sounding distractors. Experiments 1 and 2 showed the predicted interference effect in conditions with high memory load and verbal cues. In Experiment 3, eye-movement results showed that phonological interference resulted from small increases in dwell time to all distractors. The results suggest that distractor names are implicitly activated during search, slowing attention disengagement when targets and distractors share similar names.