Conditions Of Low Perceptual Load Research Articles

Is processing superiority a universal trait for all threats? Divergent impacts of fearful, angry, and disgusted faces on attentional capture

Fearful, angry, and disgusted facial expressions are evolutionarily salient and convey different types of threat signals. However, it remains unclear whether these three expressions impact sensory perception and attention in the same way. The present ERP study investigated the temporal dynamics underlying the processing of different types of threatening faces and the impact of attentional resources employed during a perceptual load task. Participants were asked to judge the length of bars superimposed over faces presented in the center of the screen. A mass univariate statistical approach was used to analyze the EEG data. Behaviorally, task accuracy was significantly reduced following exposure to fearful faces relative to neutral distractors, independent of perceptual load. The ERP results revealed that the P1 amplitude over the right hemisphere was found to be enhanced for fearful relative to disgusted faces, reflecting the rapid and coarse detection of fearful cues. The N170 responses elicited by fearful, angry, and disgusted faces were larger than those elicited by neutral faces, suggesting the largely automatic and preferential processing of threats. Furthermore, the early posterior negativity (EPN) component yielded increased responses to fearful and angry faces, indicating prioritized attention to stimuli representing acute threats. Additionally, perceptual load exerted a pronounced influence on the EPN and late positive potential (LPP), with larger responses observed in the low perceptual load condition, indicating goal-directed cognitive processing. Overall, the early sensory processing of fearful, angry, and disgusted faces is characterized by differential sensitivity in capturing attention automatically, despite the importance of these facial signals for survival. Fearful faces produce a strong interference effect and are processed with higher priority than angry and disgusted ones.

Effect of Auditory Distractors on Speech Recognition and Listening Effort.

Everyday listening environments are filled with competing noise and distractors. Although significant research has examined the effect of competing noise on speech recognition and listening effort, little is understood about the effect of distraction. The framework for understanding effortful listening recognizes the importance of attention-related processes in speech recognition and listening effort; however, it underspecifies the role that they play, particularly with respect to distraction. The load theory of attention predicts that resources will be automatically allocated to processing a distractor, but only if perceptual load in the listening task is low enough. If perceptual load is high (i.e., listening in noise), then resources that would otherwise be allocated to processing a distractor are used to overcome the increased perceptual load and are unavailable for distractor processing. Although there is ample evidence for this theory in the visual domain, there has been little research investigating how the load theory of attention may apply to speech processing. In this study, we sought to measure the effect of distractors on speech recognition and listening effort and to evaluate whether the load theory of attention can be used to understand a listener's resource allocation in the presence of distractors. Fifteen adult listeners participated in a monosyllabic words repetition task. Test stimuli were presented in quiet or in competing speech (+5 dB signal-to-noise ratio) and in distractor or no distractor conditions. In conditions with distractors, auditory distractors were presented before the target words on 24% of the trials in quiet and in noise. Percent-correct was recorded as speech recognition, and verbal response time (VRT) was recorded as a measure of listening effort. A significant interaction was present for speech recognition, showing reduced speech recognition when distractors were presented in the quiet condition but no effect of distractors when noise was present. VRTs were significantly longer when distractors were present, regardless of listening condition. Consistent with the load theory of attention, distractors significantly reduced speech recognition in the low-perceptual load condition (i.e., listening in quiet) but did not impact speech recognition scores in conditions of high perceptual load (i.e., listening in noise). The increases in VRTs in the presence of distractors in both low- and high-perceptual load conditions (i.e., quiet and noise) suggest that the load theory of attention may not apply to listening effort. However, the large effect of distractors on VRT in both conditions is consistent with the previous work demonstrating that distraction-related shifts of attention can delay processing of the target task. These findings also fit within the framework for understanding effortful listening, which proposes that involuntary attentional shifts result in a depletion of cognitive resources, leaving less resources readily available to process the signal of interest; resulting in increased listening effort (i.e., elongated VRT).

Effects of Temporal Characteristics on Pilots Perceiving Audiovisual Warning Signals Under Different Perceptual Loads.

Our research aimed to investigate the effectiveness of auditory, visual, and audiovisual warning signals for capturing the attention of the pilot, and how stimulus onset asynchronies (SOA) in audiovisual stimuli affect pilots perceiving the bimodal warning signals under different perceptual load conditions. In experiment 1 of the low perceptual load condition, participants discriminated the location (right vs. left) of visual targets preceded by five different types of warning signals. In experiment 2 of high perceptual load, participants completed the location task identical to a low load condition and a digit detection task in a rapid serial visual presentation (RSVP) stream. The main effect of warning signals in two experiments showed that visual and auditory cues presented simultaneously (AV) could effectively and efficiently arouse the attention of the pilots in high and low load conditions. Specifically, auditory (A), AV, and visual preceding auditory stimulus by 100 ms (VA100) increased the spatial orientation to a valid position in low load conditions. With the increase in visual perceptual load, auditory preceding the visual stimulus by 100 ms (AV100) and A warning signals had stronger spatial orientation. The results are expected to theoretically support the optimization design of the cockpit display interface, contributing to immediate flight crew awareness.

High bladder pressure reduces the ability to filter out interference from distractors in low perceptual load condition.

According to the load theory of attention, an active cognitive control mechanism is needed to ensure that behaviour is controlled by target-relevant information when distractors are also perceived. Although the active cognitive control mechanism consists of working memory, cognitive flexibility, and inhibition components, predictions regarding the load effects of this mechanism were derived mostly from studies on working memory. We aimed to test whether these predictions are also valid for an inhibition component. The inhibitory load was manipulated physiologically by creating different bladder pressure and its effects on distractor interference were examined under low and high perceptual load conditions. The results indicated that the availability of inhibitory control resources was important for decreasing the interference of distractors in the low perceptual load condition and that the high perceptual load reduced the effects of distractors independently from the availability of inhibitory resources. The results were consistent with the predictions of load theory, and to the best of our knowledge, the study provided the first piece of evidence in terms of the load effect of inhibition component on distractor interference.

Anterior cingulate cortex activity during attentional control corresponds with rumination in depression and social anxiety

Rumination and worry are transdiagnostic perseverative cognitions that have overlapping and distinct characteristics. While the mechanisms of perseverative cognitions remain incomplete, limited data indicate anterior cingulate cortex (ACC) as it relates to top-down functions contributes to perseverative cognitions in internalizing conditions. The current study extends this work in patients with major depression (n = 39) or social anxiety (n = 42). During fMRI, participants viewed images comprising letter strings superimposed on task-irrelevant threatening or neutral faces. To moderate task difficulty, there was a low perceptual load condition where the target letter was in a string of identical letters and high load condition with the target letter in a mixed letter string increasing task difficulty. Regions of interest (ROI) comprised dorsal ACC and rostral ACC. Bilateral amygdala was also examined. Results showed diagnostic groups had similar levels of rumination and worry. Exploratory hierarchical regression analysis comprising clinical measures, task performance, and the 4 ROIs revealed significantly less dorsal ACC engagement during low (vs. high) load to task-irrelevant faces corresponded with more rumination, but not worry, regardless of diagnostic status. However, the ACC finding did not survive Bonferroni correction. Preliminary results suggest dorsal ACC response during attentional control may serve as a transdiagnostic mechanism of rumination.

Loads of unconscious processing: The role of perceptual load in processing unattended stimuli during inattentional blindness

Inattentional blindness describes the failure to detect an unexpected but clearly visible object when our attention is engaged elsewhere. While the factors that determine the occurrence of inattentional blindness are already well understood, there is still a lot to learn about whether and how we process unexpected objects that go unnoticed. Only recently it was shown that although not consciously aware, characteristics of these stimuli can interfere with a primary task: Classification of to-be-attended stimuli was slower when the content of the task-irrelevant, undetected stimulus contradicted that of the attended, to-be-judged stimuli. According to Lavie’s perceptual load model, irrelevant stimuli are likely to reach awareness under conditions of low perceptual load, while they remain undetected under high load, as attentional resources are restricted to the content of focused attention. In the present study, we investigated the applicability of Lavie’s predictions for the processing of stimuli that remain unconscious due to inattentional blindness. In two experiments, we replicated that unconsciously processed stimuli can interfere with intended responses. Also, our manipulation of perceptual load did have an effect on primary task performance. However, against our hypothesis, these effects did not interact with each other. Thus, our results suggest that high perceptual load cannot prevent task-irrelevant stimuli that remain undetected from being processed to an extent that enables them to affect performance in a primary task.

A Novel Test of Pure Irrelevance-Induced Blindness

Load theory claims that bottom-up attention is possible under conditions of low perceptual load but not high perceptual load. At variance with this claim, a recent one-trial study showed that under low load, with only two colors in the display – a ring and a disk –, an instruction to process only one of the two stimuli led to better memory performance for the color of the relevant than of the irrelevant stimulus. Control experiments showed that if instructed to pay attention to both objects, participants were able to memorize both colors. Thus, stimulus irrelevance diminished the likelihood of memory for a color stimulus under low perceptual-load conditions. Yet, we noted less than optimal design features in that prior study: a lack of more implicit priming measures of memory or attention and an interval between color stimulus presentation and memory test that probably exceeded 500 ms. We took care of these problems in the current one-trial study by improving the retrieval displays while leaving the encoding displays as in the original study and found that the results only partly replicated prior findings. In particular, there was no evidence of irrelevance-induced blindness under conditions in which a ring was designated as relevant, surrounding an irrelevant disk. However, a continuously cumulative meta-analysis across past and present experiments showed that our results do not refute the irrelevance-induced effects entirely. We conclude with recommendations for future tests of load theory.

Greater Response Interference to Pain Faces Under Low Perceptual Load Conditions in Adolescents With Impairing Pain: A Role for Poor Attention Control Mechanisms in Pain Disability?

Persistent pain in young people in the community is common, but individuals vary in how much pain impacts daily life. Information-processing accounts of chronic pain partly attribute the fear and avoidance of pain, as well as associated interference, to a set of involuntary biases, including the preferential allocation of attention resources toward potential threats. Far less research has focused on the role of voluntary goal-directed attention control processes, the ability to flexibly direct attention toward and away from threats, in explaining pain-associated interference. Using a visual search task, we explored a poor attention control account of pain interference in young people with persistent pain from the community. One hundred and forty five young people aged 16 to 19 years were categorized into three groups: non-chronic pain (n = 68), low-interfering persistent pain (n = 40), and moderate- to high-interfering persistent pain (n = 22). We found that only adolescents with moderate-to high-interfering persistent pain but not the other two groups of adolescents were affected by a search task preceded by a pain face (compared to a neutral face), but this within-group difference emerged only under low perceptual load conditions. Because low perceptual load conditions are thought to require more strategic attention resources to suppress the interfering effects of pain face primes, our findings are consistent with a poor attention control account of pain interference in young people. Analyses further showed that these differences in task performance were not explained by confounding effects of anxiety. If replicated, these findings may have implications for understanding and managing the pain-associated disability in adolescents with chronic pain. PerspectiveYoung people with moderately and highly interfering pain responded slower on an easy search task after seeing a pain face than after seeing a neutral face. If replicated, these findings could mean that boosting the ability to control attention toward and away from threatening cues is an effective strategy for managing interference from pain.

Trait attentional control modulates neurofunctional response to threat distractors in anxiety and depression

Accumulating data suggest attentional control capability varies across psychiatric diagnostic boundaries. The Attentional Control Scale (ACS) assesses self-reported trait attentional control (TAC) and tracks the anterior attention system. Greater TAC is associated with less negative affect, however, its mechanisms in anxiety and depression are poorly understood. Therefore, we examined whether individual differences in TAC modulated top-down mechanisms in a clinical sample. During fMRI, 104 patients with social anxiety, generalized anxiety, and/or major depression and 34 healthy participants completed a validated attentional control paradigm comprising strings of letters superimposed on threatening and neutral face distractors. In the low perceptual load condition, a target letter was in a string of identical letters. In the high load condition, a target letter was in a mixed letter string. Whole-brain regression results for low load revealed more activation to threat (vs. neutral) distractors in the pregenual anterior cingulate cortex was predicted by better TAC (i.e., higher ACS scores). For high load, regression results showed less activation to threat (vs. neutral) distractors in the inferior frontal gyrus was predicted by better TAC. An exploratory whole-brain ANOVA revealed a main effect of group in the superior temporal gyrus and a main effect of perceptual load in parietal, frontal, and limbic regions. No other effects were detected and activation derived from significant ANOVA results did not correlate with ACS scores. In conclusion, regression findings suggest individual differences in brain-behavioral ACS-related activity in frontal structures may be useful in identifying phenotypes in internalizing conditions.

The influence of visual flow and perceptual load on locomotion speed

Visual flow is used to perceive and regulate movement speed during locomotion. We assessed the extent to which variation in flow from the ground plane, arising from static visual textures, influences locomotion speed under conditions of concurrent perceptual load. In two experiments, participants walked over a 12-m projected walkway that consisted of stripes that were oriented orthogonal to the walking direction. In the critical conditions, the frequency of the stripes increased or decreased. We observed small, but consistent effects on walking speed, so that participants were walking slower when the frequency increased compared to when the frequency decreased. This basic effect suggests that participants interpreted the change in visual flow in these conditions as at least partly due to a change in their own movement speed, and counteracted such a change by speeding up or slowing down. Critically, these effects were magnified under conditions of low perceptual load and a locus of attention near the ground plane. Our findings suggest that the contribution of vision in the control of ongoing locomotion is relatively fluid and dependent on ongoing perceptual (and perhaps more generally cognitive) task demands.

Is there a link between media-multitasking and the executive functions of filtering and response inhibition?

Media-multitasking refers to utilising at least two forms of media simultaneously. This study examined the link between media-multitasking and the inhibitory control executive function. Performance on measures of filtering (flanker task) and inhibitory response control (Go/No-Go task) were compared across heavy media multitaskers (HMM), average media multitaskers (AMM) and light media multitaskers (LMM). For both tasks performance was better under low than high perceptual load conditions. For the flanker task, there was an effect of distractor congruency only for the low perceptual load and no performance differences between the media groups. For the Go/No-Go task, there was a distractor congruency effect for the LMM and HMM for the Go-trials. For the No-Go trials there was no difference between the groups’ performance in the low perceptual load condition. The AMM were more adversely affected by the higher perceptual load than the LMM or HMM particularly when the distractors were incongruent and neutral relative to the targets. These results suggest a link between average levels of media-multitasking and the inhibitory control executive function.

Visual Distractors Disrupt Audiovisual Integration Regardless of Stimulus Complexity.

The intricate relationship between multisensory integration and attention has been extensively researched in the multisensory field; however, the necessity of attention for the binding of multisensory stimuli remains contested. In the current study, we investigated whether diverting attention from well-known multisensory tasks would disrupt integration and whether the complexity of the stimulus and task modulated this interaction. A secondary objective of this study was to investigate individual differences in the interaction of attention and multisensory integration. Participants completed a simple audiovisual speeded detection task and McGurk task under various perceptual load conditions: no load (multisensory task while visual distractors present), low load (multisensory task while detecting the presence of a yellow letter in the visual distractors), and high load (multisensory task while detecting the presence of a number in the visual distractors). Consistent with prior studies, we found that increased perceptual load led to decreased reports of the McGurk illusion, thus confirming the necessity of attention for the integration of speech stimuli. Although increased perceptual load led to longer response times for all stimuli in the speeded detection task, participants responded faster on multisensory trials than unisensory trials. However, the increase in multisensory response times violated the race model for no and low perceptual load conditions only. Additionally, a geometric measure of Miller’s inequality showed a decrease in multisensory integration for the speeded detection task with increasing perceptual load. Surprisingly, we found diverging changes in multisensory integration with increasing load for participants who did not show integration for the no load condition: no changes in integration for the McGurk task with increasing load but increases in integration for the detection task. The results of this study indicate that attention plays a crucial role in multisensory integration for both highly complex and simple multisensory tasks and that attention may interact differently with multisensory processing in individuals who do not strongly integrate multisensory information.

Sleepless night, restless mind: Effects of sleep deprivation on mind wandering.

Sleep deprivation can result in degradation of sustained attention through increased distraction by task-irrelevant exogenous stimuli. However, attentional failures in the sleep-deprived state could also be a result of task-unrelated thoughts (TUTs, or mind wandering). Here, well-rested and sleep-deprived participants performed a visual search task under high and low perceptual load conditions. Thought probes were administered at irregular intervals to gauge the frequency of TUTs and level of meta-awareness of mind wandering. Despite sleep-deprived participants reporting more TUTs, they also reported less awareness of TUTs. Although the frequency of TUTs decreased in the high load condition in well-rested participants, they were equally frequent across low and high perceptual load conditions in sleep-deprived participants. Together, these findings suggest that sleep deprivation can result in a loss of ability to allocate attentional resources according to task demands consistent with diminished executive control. This may have been exacerbated by reduced meta-awareness. (PsycINFO Database Record

Long-Term Exposure to High Altitude Affects Voluntary Spatial Attention at Early and Late Processing Stages

The neurocognitive basis of the effect of long-term high altitude exposure on voluntary attention is unclear. Using event related potentials, the high altitude group (people born in low altitude but who had lived at high altitude for 3 years) and the low altitude group (living in low altitude only) were investigated using a voluntary spatial attention discrimination task under high and low perceptual load conditions. The high altitude group responded slower than the low altitude group, while bilateral N1 activity was found only in the high altitude group. The P3 amplitude was smaller in the high altitude compared to the low altitude group only under high perceptual load. These results suggest that long-term exposure to high altitudes causes hemispheric compensation during discrimination processes at early processing stages and reduces attentional resources at late processing stages. In addition, the effect of altitude during the late stage is affected by perceptual load.

Visual salience can co-exist with dilution during visual selection.

The perceptual load theory contends that the locus of visual selection is dependent on the availability of perceptual resources, and findings have shown significant distractor interference under conditions of low perceptual load, but not under conditions of high perceptual load. Recently, other researchers have suggested that this pattern of distractor interference may actually be due to changes in the quality of the distractor's representation (known as the dilution account) and/or changes in its relative salience (known as the salience account). The present study attempted to advance theoretical understanding of visual selection by comparing the effects of high versus low visual salience while holding the effects of perceptual load and dilution constant. The results of two experiments showed that the relative salience of the distractor influenced the magnitude of distractor interference under these conditions. These results suggest that the effects of visual salience can coexist with the effects of dilution (and load).

Acute Effects of Sceletium tortuosum (Zembrin), a Dual 5-HT Reuptake and PDE4 Inhibitor, in the Human Amygdala and its Connection to the Hypothalamus

The South African endemic plant Sceletium tortuosum has a long history of traditional use as a masticatory and medicine by San and Khoikhoi people and subsequently by European colonial farmers as a psychotropic in tincture form. Over the past decade, the plant has attracted increasing attention for its possible applications in promoting a sense of wellbeing and relieving stress in healthy individuals and for treating clinical anxiety and depression. The pharmacological actions of a standardized extract of the plant (Zembrin) have been reported to be dual PDE4 inhibition and 5-HT reuptake inhibition, a combination that has been argued to offer potential therapeutic advantages. Here we tested the acute effects of Zembrin administration in a pharmaco-fMRI study focused on anxiety-related activity in the amygdala and its connected neurocircuitry. In a double-blind, placebo-controlled, cross-over design, 16 healthy participants were scanned during performance in a perceptual-load and an emotion-matching task. Amygdala reactivity to fearful faces under low perceptual load conditions was attenuated after a single 25 mg dose of Zembrin. Follow-up connectivity analysis on the emotion-matching task showed that amygdala–hypothalamus coupling was also reduced. These results demonstrate, for the first time, the attenuating effects of S. tortuosum on the threat circuitry of the human brain and provide supporting evidence that the dual 5-HT reuptake inhibition and PDE4 inhibition of this extract might have anxiolytic potential by attenuating subcortical threat responsivity.

Negative affective state mimics effects of perceptual load on spatial perception.

Recent electrophysiological evidence has shown that perceptual load and negative affective state can produce very similar, early-attention gating effects in early visual areas, modulating the processing of peripheral stimuli. Here we assessed the question of whether or not these modulatory effects of perceptual load and negative affect (NA) lead to comparable changes in spatial perception abilities, which could be captured at the behavioral level. High perceptual load at fixation impaired the precise spatial localization of peripheral textures, relative to a low perceptual load condition. By contrast, the coarse spatial encoding of these peripheral stimuli was not load-dependent, under neutral affective conditions. The transient experience of NA was induced in an independent sample of participants, who showed decreased performance in the localization task, even at a low perceptual-load level. These results were observed in the absence of any systematic eye movement toward the peripheral textures. These findings suggest that spatial location perception is an attention-dependent, as well as state-dependent process, in the sense that NA, very much like load, can dynamically shape early spatial perceptual abilities. Although NA mimics load during spatial localization, we discuss the possibility that these two effects likely depend upon nonoverlapping brain networks.

Effects of mental fatigue on the capacity limits of visual attention

The literature indicates that mental fatigue, due to Time-on-Task (ToT), compromises the ability to ignore distractors. The present study elaborates on this effect by testing whether perceptual load of the target stimuli moderates the ability to ignore distractors under fatigue. Participants (N = 27) performed a visual attention task (an Eriksen flanker task) for 2.5 hours without rest. Target letters were presented at three different perceptual loads and with a peripheral distractor letter. Three target–distractor conditions were tested: congruent, incongruent, and neutral. Results showed that, overall, error rates and reaction times increased with ToT. The detrimental effect of fatigue on performance was most pronounced in the high perceptual load condition. Importantly, however, we also found that fatigue-related ignorance of distractors was compromised in the low perceptual load condition, but not in the medium or high perceptual load condition. This finding is in accordance with the perceptual load theory and refines the knowledge about the declining cognitive performance under fatigue.

The effects of acute stress and perceptual load on distractor interference

Selective attention can be improved under conditions in which a high perceptual load is assumed to exhaust cognitive resources, leaving scarce resources for distractor processing. The present study examined whether perceptual load and acute stress share common attentional resources by manipulating perceptual and stress loads. Participants identified a target within an array of nontargets that were flanked by compatible or incompatible distractors. Attentional selectivity was measured by longer reaction times in response to the incompatible than to the compatible distractors. Participants in the stress group participated in a speech test that increased anxiety and threatened self-esteem. The effect of perceptual load interacted with the stress manipulation in that participants in the control group demonstrated an interference effect under the low perceptual load condition, whereas such interference disappeared under the high perceptual load condition. Importantly, the stress group showed virtually no interference under the low perceptual load condition, whereas substantial interference occurred under the high perceptual load condition. These results suggest that perceptual and stress related demands consume the same attentional resources.

Attentional capture by angry faces depends on the distribution of attention

Event Abstract Back to Event Attentional capture by angry faces depends on the distribution of attention Joshua J. Foster1*, David Carmel2 and Gina M. Grimshaw1 1 Victoria University of Wellington, New Zealand 2 The University of Edinburgh, Scotland According to the threat-capture hypothesis (Fenker et al., 2010), threatening stimuli activate a threat-detection mechanism, which directs attention to their location. Importantly, this mechanism is theorised to operate preattentively (i.e., in a capacity-free manner). It follows that threatening stimuli should capture attention when they are task-irrelevant, even when attention is engaged elsewhere. We tested this prediction in two experiments. In Experiment 1, participants identified a lateralised target that followed a non-informative bilateral display, consisting of one neutral and one angry face. Task demands ensured that attention was broadly distributed across the face display. In Experiment 2, participants performed a central letter-classification task, under conditions of high or low perceptual load, while ignoring the same bilateral face displays. We recorded ERPs time-locked to the onset of the face displays to examine the N2pc component, an index of attentional selection. An N2pc for angry faces was observed in Experiment 1, suggesting that they capture attention when it is broadly distributed. This effect was preserved when the faces were Fourier phase scrambled, suggesting that attentional capture is driven by low-level visual information and not the emotion per se. The N2pc effect was abolished in Experiment 2, even under conditions of low perceptual load, suggesting that concurrent target processing eliminates attentional capture by angry faces. These findings challenge the threat-capture hypothesis; angry faces are preferentially processed under conditions of distributed attention but not when attention is engaged elsewhere. References Fenker, D. B., Heipertz, D., Boehler, C. N., Schoenfeld, M. A., Noesselt, T., Henze, H-J., Duezel, E., and Hopf, J-M. (2010). Mandatory processing of irrelevant fearful face features in visual search. J Cognitive Neurosci 22, 2926-2938. Keywords: Attention, emotion, perceptual load, ERPs, N2pc Conference: ACNS-2012 Australasian Cognitive Neuroscience Conference, Brisbane, Australia, 29 Nov - 2 Dec, 2012. Presentation Type: Poster Presentation Topic: Attention Citation: Foster JJ, Carmel D and Grimshaw GM (2012). Attentional capture by angry faces depends on the distribution of attention. Conference Abstract: ACNS-2012 Australasian Cognitive Neuroscience Conference. doi: 10.3389/conf.fnhum.2012.208.00037 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 14 Oct 2012; Published Online: 07 Nov 2012. * Correspondence: Mr. Joshua J Foster, Victoria University of Wellington, Wellington, New Zealand, joshua.foster@vuw.ac.nz Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Joshua J Foster David Carmel Gina M Grimshaw Google Joshua J Foster David Carmel Gina M Grimshaw Google Scholar Joshua J Foster David Carmel Gina M Grimshaw PubMed Joshua J Foster David Carmel Gina M Grimshaw Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.