Concurrent Visual Task Research Articles

Visuospatial Processing in Memory for Word Location in Writing

Two experiments examined how visuospatial processing engaged during text composition intervenes in memory for word location. Experiment 1 showed that in contrast to participants who performed a spatial task concurrently with composing a text, participants who performed a concurrent visual task recalled fewer word locations after the composition. Consequently, it is hypothesized that writers process the written text in order to visually represent its physical layout, and that this representation is then used when locating words. Experiment 2 tested this hypothesis by comparing a standard composition condition (with the written trace) with a condition in which the written trace was suppressed during composition, and with a condition without written trace and with added visual noise. Memory for word location only decreased with visual noise, indicating that construction of the visual representation of the text does not rely on the written trace but involves visual working memory.

Release of inattentional blindness by high working memory load: Elucidating the relationship between working memory and selective attention

An unexpected stimulus often remains unnoticed if attention is focused elsewhere. This inattentional blindness has been shown to be increased under conditions of high memory load. Here we show that increasing working memory load can also have the opposite effect of reducing inattentional blindness (i.e., improving stimulus detection) if stimulus detection is competing for attention with a concurrent visual task. Participants were required to judge which of two lines was the longer while holding in working memory either one digit (low load) or six digits (high load). An unexpected visual stimulus was presented once alongside the line judgment task. Detection of the unexpected stimulus was significantly improved under conditions of higher working memory load. This improvement in performance prompts the striking conclusion that an effect of cognitive load is to increase attentional spread, thereby enhancing our ability to detect perceptual stimuli to which we would normally be inattentionally blind under less taxing cognitive conditions. We discuss the implications of these findings for our understanding of the relationship between working memory and selective attention.

Effects of cognitive load on speech recognition

The effect of cognitive load (CL) on speech recognition has received little attention despite the prevalence of CL in everyday life, e.g., dual-tasking. To assess the effect of CL on the interaction between lexically-mediated and acoustically-mediated processes, we measured the magnitude of the “Ganong effect” (i.e., lexical bias on phoneme identification) under CL and no CL. CL consisted of a concurrent visual search task. Experiment 1 showed an increased Ganong effect under CL. A time-course analysis of this pattern (Experiments 2 and 3) revealed that the Ganong effect decreased over time under optimal conditions, but it did not under CL. Thus, CL appears to be delaying (and perhaps preventing) listeners’ ability to rely on fine phonetic detail to perform the sub-lexical task. This finding, along with an absence of measurable effects at the post-lexical level (Experiment 4) or at the lexical level (Experiment 5) and a clear negative effect of CL on perceptual discrimination (Experiment 6), suggests that the increased reliance on lexically-mediated processes under CL is the cascaded effect of impoverished encoding of the sensory input. Ways of implementing a link between CL and sensory analysis into existing models of speech recognition are proposed.

A Comparison of Visual Versus Auditory Concurrent Tasks on Reducing the Distress and Vividness of Aversive Autobiographical Memories

This study investigated the benefits of eye movement similar to that used in eye movement desensitization and reprocessing (EMDR) on reducing the vividness and emotionality of negative autobiographical memories. It was hypothesized, based on the working memory model, that any task that disrupts working memory would reduce the vividness and emotionality of distressing memories. In addition, it was predicted that the more visual a memory, the greater the reduction in vividness by a concurrent visual task over an auditory task (counting). Thirty-six nonclinical participants were asked to recall an unpleasant autobiographical memory while performing each of three dual-attention tasks: eye movement, listening to counting, or control (short exposure). Results showed that vividness and emotionality ratings of the memory decreased significantly after eye movement and counting, and that eye movement produced the greatest benefit. Furthermore, eye movement facilitated greater decrease in vividness irrespective of the modality of the memory. Although this is not consistent with the hypothesis from a working memory model of mode-specific effects, it is consistent with a central executive explanation. Implications for enhancing exposure treatment for posttraumatic stress disorder (PTSD) are discussed.

Aversive picture processing: Effects of a concurrent task on sustained defensive system engagement

Viewing a series of aversive pictures prompts emotional reactivity reflecting sustained defensive engagement. The present study examined the effects of a concurrent visual task on autonomic, somatic, electrocortical, and facial components of this defensive state. Results indicated that emotional activation was largely preserved despite continuous visual distraction, although evidence of attenuation was observed in startle reflex and electrocortical measures. Concurrent task-specific reactivity was also apparent, suggesting that motivational circuits can be simultaneously activated by stimuli with intrinsic survival significance and instructed task significance and that these processes interact differently across the separate components of defensive engagement.

Age-related deficits of dual-task walking: The role of foot vision

Previous studies found that age-related deficits of dual-task walking emerge with secondary tasks that require substantial visual processing, but are absent with tasks that require little or no visual processing. We evaluated whether this is so because visual tasks typically interfere with foot vision, on which older persons depend more heavily than young ones. Young (25±3 years) and older (69±5 years) subjects walked along a straight path and checked boxes on a handheld panel, separately or concurrently. The panel was either transparent or opaque, thus allowing or blocking vision of the feet, respectively. We quantified subjects’ performance by spatial and temporal gait measures, and as the speed of checking. An analysis of variance revealed significant effects of age and of condition (single, dual) for several gait measures, as well as for checking speed. The dual-task costs (ǀdual−singleǀ/single) averaged 0.04±0.14 in younger and 0.33±0.30 in older subjects; this age difference was significant in a t-test (p<0.01). Most importantly, performance measures obtained with the transparent and with the opaque panel were not significantly different. In conclusion, our study confirms previous findings about age-related deficits of walking with a concurrent visual task, documents for the first time that these deficits influence the entire spatio-temporal gait structure, but provides no support for the notion that they reflect an increased dependence on foot vision.

Off-Vertical Axis Rotation of the Visual Field and Nauseogenicity

Off-vertical axis rotation (OVAR) causes motion sickness which increases with angle of tilt and is most provocative around 0.2 Hz. The aim was to determine the tilt angle and frequency characteristics for visual OVAR, which is also known to be nauseogenic. A computerized scene, as seen by a pilot at moderate altitude, rotated at different frequencies about an axis which could tilt as during OVAR. A concurrent visual detection task controlled attention. Exposures were for 10 min or until nausea developed. There were four experiments: Frequency tuning-visual motion at 0.05, 0.2, and 0.8 Hz, all at 18 degrees tilt of the axis of rotation (N = 14); gross visual tilt tuning-visual motion at 0, 45, and 90 degrees of tilt at 0.2 Hz (N = 12); fine visual tilt tuning -- 18, 36, 54, and 72 degrees tilts at 0.2 Hz (N = 24); and whole-body tilt of the participant at 0, 45, and 90 degrees, viewing rotation about a vertical axis at 0.2 Hz (N = 12). Nauseogenicity was significantly greater at 0.2 Hz than at lower or higher frequencies. Visual tilts 18 degrees to circa 45 degrees were significantly more nauseogenic. No differences were found between whole-body tilts. Nauseogenicity of visual OVAR peaks around 0.2 Hz, and increases with stimulus strength up to circa 45 degrees tilt, similar to real motion. With higher tilt angles, decreasing nauseogenicity suggests that the visual impact is partially quarantined because the motion would appear patently absurd and not a sensory conflict. Whole-body tilt may have failed to modulate nauseogenicity because of overriding somatosensory cues to Earth vertical.

Neural signature of the conscious processing of auditory regularities

Can conscious processing be inferred from neurophysiological measurements? Some models stipulate that the active maintenance of perceptual representations across time requires consciousness. Capitalizing on this assumption, we designed an auditory paradigm that evaluates cerebral responses to violations of temporal regularities that are either local in time or global across several seconds. Local violations led to an early response in auditory cortex, independent of attention or the presence of a concurrent visual task, whereas global violations led to a late and spatially distributed response that was only present when subjects were attentive and aware of the violations. We could detect the global effect in individual subjects using functional MRI and both scalp and intracerebral event-related potentials. Recordings from 8 noncommunicating patients with disorders of consciousness confirmed that only conscious individuals presented a global effect. Taken together these observations suggest that the presence of the global effect is a signature of conscious processing, although it can be absent in conscious subjects who are not aware of the global auditory regularities. This simple electrophysiological marker could thus serve as a useful clinical tool.

The role of the orbitofrontal cortex in human discrimination learning

Several lines of evidence implicate the prefrontal cortex in learning but there is little evidence from studies of human lesion patients to demonstrate the critical role of this structure. To this end, we tested patients with lesions of the frontal lobe (n=36) and healthy controls (n=35) on two learning tasks: the weather prediction task (WPT), and an eight-pair concurrent visual discrimination task (‘Choose’). Performance of both tasks was previously shown to be disrupted in patients with Parkinson's disease; the Choose deficit was only present when patients were medicated. Patients with damage to the orbitofrontal cortex (OFC) were significantly impaired on Choose, compared to both healthy controls and non-OFC lesion patients. The OFC lesion patients showed a mild deficit on the first 50 trials of the WPT, compared to the control subjects but not non-OFC lesion patients. The selective deficit in the OFC patients on Choose performance could not be attributed to the larger lesion size in this group, and the deficit was not correlated with the volume of damage to adjacent prefrontal subregions (e.g. anterior cingulate cortex). These data support the notion that the OFC play a role in normal discrimination learning, and suggest qualitative similarities in learning performance of patients with OFC damage and medicated PD patients.

Tactons in multitask environments: The interaction of presentation modality and processing code

Tactons, or vibrotactile icons, have been proposed as a means to communicate complex concepts to users and to support multitasking in environments involving numerous visual and/or auditory tasks and stimuli. This study investigated the role of processing code in the interpretation of tactons while performing concurrent visual tasks in such environments. Participants decoded tactons composed of spatiotemporal patterns of vibrations – requiring spatial processing – and interpreted one of two types of visual task stimuli – requiring either spatial or categorical processing – in a driving simulation. Compared to single-task performance, there was a significantly larger dual-task performance decrement when the tacton task was paired with the visual task requiring spatial (as compared to categorical) processing. The findings are consistent with the assertion of Multiple Resource Theory that interference between concurrent tasks is greater when these tasks involve the same processing code. They illustrate how distributing task-related information across modalities is beneficial but not sufficient to avoid task interference. A direct implication of the findings is to avoid the use of spatiotemporal tactons in environments which rely heavily on spatial processing resources, such as car cockpits or flight decks.

Separate attentional resources for vision and audition

Current models of attention, typically claim that vision and audition are limited by a common attentional resource which means that visual performance should be adversely affected by a concurrent auditory task and vice versa. Here, we test this implication by measuring auditory (pitch) and visual (contrast) thresholds in conjunction with cross-modal secondary tasks and find that no such interference occurs. Visual contrast discrimination thresholds were unaffected by a concurrent chord or pitch discrimination, and pitch-discrimination thresholds were virtually unaffected by a concurrent visual search or contrast discrimination task. However, if the dual tasks were presented within the same modality, thresholds were raised by a factor of between two (for visual discrimination) and four (for auditory discrimination). These results suggest that at least for low-level tasks such as discriminations of pitch and contrast, each sensory modality is under separate attentional control, rather than being limited by a supramodal attentional resource. This has implications for current theories of attention as well as for the use of multi-sensory media for efficient informational transmission.

Investigating slips, trips and falls in the New Zealand dairy farming sector

The paper presents findings from 39 detailed follow-up investigations of slips, trips and falls (STF) incurred by individuals working in New Zealand's dairy farming industry. The study sought to identify the key contributory risk factors for STF in this sector to provide evidence to support intervention design, and to determine the effectiveness of the investigative methodology used to achieve these objectives. Findings from the follow-up investigations included an analysis of factors related to the underfoot surface, underfoot hazard and footwear. Of note here was the propensity for STF-involved workers to not see or identify an underfoot hazard due to concurrent visual task distractions, and for workers to use footwear that both lacked effective tread and was unsuitable for the task and underfoot surface. Key latent risk factors and their interactions identified included problems associated with time pressure and related time-saving behaviours and the presence of design errors that, for example, required workers to climb onto equipment to view aspects of the task they were working on. The paper concludes that the potential resource and logistical problems associated with conducting detailed STF investigations are outweighed by the opportunity to collect rich data on key risk factors and their interactions in STF research.

Visuo-spatial working memory deficits in current and former users of MDMA (?ecstasy?)

Verbal working memory and executive deficits have been observed in ecstasy users. The present study sought to establish whether these also extended to visuo-spatial working memory. Thirty-six current ecstasy users, 12 former users (abstinent for at least 6 months) and 31 individuals that had never used ecstasy were tested on a maintenance plus type visuo-spatial working memory task. The task required participants to recall a sequence of specially marked cells in a four-by-four matrix display while at the same time performing a concurrent visual judgement task. Both the current and former user groups registered impairments relative to nonusers. These remained significant following statistical controls for a range of potentially confounding variables including the use of various other drugs during the 3 months prior to testing. Users were unimpaired on a simple spatial span measure suggesting that the deficits observed reflected the executive aspects of the spatial working memory task. Also consistent with executive involvement, statistical controls for measures of verbal working memory performance (computation span) removed half of the ecstasy-related variance in spatial working memory. The possibility that the pattern of results obtained might reflect some general impairment in information processing efficiency is discussed.

Amygdala Activation to Sad Pictures During High-Field (4 Tesla) Functional Magnetic Resonance Imaging.

Fear-related processing in the amygdala has been well documented, but its role in signaling other emotions remains controversial. The authors recovered signal loss in the amygdala at high-field strength using an inward spiral pulse sequence and probed its response to pictures varying in their degree of portrayed sadness. These pictures were presented as intermittent task-irrelevant distractors during a concurrent visual oddball task. Relative to neutral distractors, sad distractors elicited greater activation along ventral brain regions, including the amygdala, fusiform gyrus, and inferior frontal gyrus. In contrast, oddball targets engaged dorsal sectors of frontal, parietal, and cingulate cortices. The amygdala's role in emotional evaluation thus extends to images of grief and despair as well as to those depicting violence and threat.

Cortical response to subjectively unconscious danger

Cortical involvement in the evolution-favored automatic reaction to danger was studied. Electrical neural activity was recorded from 31 subjects, reporting fear of spiders, at 60 scalp locations. Visual stimuli containing spiders (negative elements) or, alternatively, nonnegative elements were presented to subjects, though they were unaware of their presence: a concurrent visual detection task using consciously perceived targets was administered. Spatial and temporal principal component analyses were employed to define and quantify, in a reliable manner, the main components of the neuroelectrical response to unconscious stimuli, and a source localization algorithm provided information on their neural origin. Results indicated that around 150 ms after stimulus onset, ventromedial prefrontal areas previously reported as responding rapidly to danger-related (conscious) stimuli were activated by unconsciously perceived spiders more markedly than by nonnegative unconscious stimuli. Subsequently, around 500 ms after stimulus onset, activation of the posterior cingulate and visual association cortices increased in this same direction. These data support previous results indicating that the ventromedial prefrontal cortex is involved in the top-down regulation of attention (through its capability to modulate the activity of posterior cortices in charge of visual processing) and that it automatically facilitates danger processing.

Automatic and controlled processing in sentence recall: The role of long-term and working memory

Immediate serial recall is better for sentences than word lists presumably because of the additional support that meaningful material receives from long-term memory. This may occur automatically, without the involvement of attention, or may require additional attentionally demanding processing. For example, the episodic buffer model ( Baddeley, 2000) proposes that the executive component of working memory plays a crucial role in the formation of links between different representational formats and previously unrelated concepts. This controlled integrative encoding may be more important in sentence than word recall. Three experiments examined the effect of an attention-demanding concurrent visual choice reaction time task on the recall of auditorily presented stories, sentences, and lists of unrelated words, in order to investigate the relative importance of automatic and controlled processing for these materials. The concurrent task was found to disrupt the recall of strings of unrelated sentences more than random word lists, suggesting that controlled processing played a greater role in the sentence recall task. On subsequent learning trials, however, recall of the unrelated words was also disrupted by the concurrent task, possibly due to the development of chunking. The large dual task decrement for unrelated sentences did not generalise to the recall of more naturalistic prose, suggesting that the requirement to integrate phonological with long-term linguistic information is not attentionally demanding per se; instead, the integration of unrelated concepts is effortful once recall extends beyond the capacity of the phonological loop. Our results suggest that sentence recall reflects contributions from both automatic linguistic processes and attentionally limited working memory.

Visual search is slowed when visuospatial working memory is occupied.

Visual working memory plays a central role in most models of visual search. However, a recent study showed that search efficiency was not impaired when working memory was filled to capacity by a concurrent object memory task (Woodman, Vogel, & Luck, 2001). Objects and locations may be stored in separate working memory subsystems, and it is plausible that visual search relies on the spatial subsystem, but not on the object subsystem. In the present study, we sought to determine whether maintaining spatial information in visual working memory impairs the efficiency of a concurrent visual search task. Visual search efficiency and spatial memory accuracy were both impaired when the search and the memory tasks were performed concurrently, as compared with when the tasks were performed separately. These findings suggest that common mechanisms are used to process information during difficult visual search tasks and to maintain spatial information in working memory.

Measurement of the visual field.

There is increasing evidence that concurrent visual and nonvisual tasks not only reduce the size but also result in systematic deformation of the visual field. Given such complex changes in the visual field, appropriate representation and measurement of its shape is all important. Shape measures utilized by researchers and reported in the literature should also be sufficiently standardized to allow comparison of results across experiments.

MEASUREMENT OF THE VISUAL FIELD

There is increasing evidence that concurrent visual and nonvisual tasks not only reduce the size but also result in systematic deformation of the visual field. Given such complex changes in the visual field, appropriate representation and measurement of its shape is all important. Shape measures utilized by tesearchcrs and reported in the literature should also be sufficiently standardized to allow comparison of results across experiments.

Utilty of a Tactile Display for Cueing Faults

Tactile displays have been proposed as a multisensory interface technology that can relieve the typically overburdened visual channel of operators. This study compared the ability of operators, while simultaneously completing a tracking task, to detect and identify system faults in a monitoring task with three types of alert cues: tactile, visual, and redundant tactile and visual. For the tactile display, the location and vibration pulse speed of two tactors were mapped to four system faults. Response time was significantly faster with the tactile cue. Also, the tactile cue resulted in less interference with the concurrent tracking task, while not degrading vigilance to an additional concurrent visual monitoring task. These results suggest that further tactile cue research is warranted to examine potential applications in complex systems, such as control stations for unmanned aerial vehicles.