Stimulus Onset Asynchrony Research Articles

Audiovisual integration in depth: multisensory binding and gain as a function of distance

The integration of information across sensory modalities is dependent on the spatiotemporal characteristics of the stimuli that are paired. Despite large variation in the distance over which events occur in our environment, relatively little is known regarding how stimulus-observer distance affects multisensory integration. Prior work has suggested that exteroceptive stimuli are integrated over larger temporal intervals in near relative to far space, and that larger multisensory facilitations are evident in far relative to near space. Here, we sought to examine the interrelationship between these previously established distance-related features of multisensory processing. Participants performed an audiovisual simultaneity judgment and redundant target task in near and far space, while audiovisual stimuli were presented at a range of temporal delays (i.e., stimulus onset asynchronies). In line with the previous findings, temporal acuity was poorer in near relative to far space. Furthermore, reaction time to asynchronously presented audiovisual targets suggested a temporal window for fast detection—a range of stimuli asynchronies that was also larger in near as compared to far space. However, the range of reaction times over which multisensory response enhancement was observed was limited to a restricted range of relatively small (i.e., 150 ms) asynchronies, and did not differ significantly between near and far space. Furthermore, for synchronous presentations, these distance-related (i.e., near vs. far) modulations in temporal acuity and multisensory gain correlated negatively at an individual subject level. Thus, the findings support the conclusion that multisensory temporal binding and gain are asymmetrically modulated as a function of distance from the observer, and specifies that this relationship is specific for temporally synchronous audiovisual stimulus presentations.

The Dyad-Adaptive Paced Auditory Serial Addition Test (DA-PASAT): Normative data and the effects of repeated testing, simulated malingering, and traumatic brain injury.

The Paced Auditory Serial Addition Test (PASAT) is widely used to evaluate processing speed and executive function in patients with multiple sclerosis, traumatic brain injury, and other neurological disorders. In the PASAT, subjects listen to sequences of digits while continuously reporting the sum of the last two digits presented. Four different stimulus onset asynchronies (SOAs) are usually tested, with difficulty increasing as SOAs are reduced. Ceiling effects are common at long SOAs, while the digit delivery rate often exceeds the subject’s processing capacity at short SOAs, causing some subjects to stop performing altogether. In addition, subjects may adopt an “alternate answer” strategy at short SOAs, which reduces the test’s demands on working-memory and processing speed. Consequently, studies have shown that the number of dyads (consecutive correct answers) is a more sensitive measure of PASAT performance than the overall number of correct sums. Here, we describe a 2.5-minute computerized test, the Dyad-Adaptive PASAT (DA-PASAT), where SOAs are adjusted with a 2:1 staircase, decreasing after each pair of correct responses and increasing after misses. Processing capacity is reflected in the minimum SOA (minSOA) achieved in 54 trials. Experiment 1 gathered normative data in two large populations: 1617 subjects in New Zealand ranging in age from 18 to 65 years, and 214 Californians ranging in age from 18 to 82 years. Minimum SOAs were influenced by age, education, and daily hours of computer-use. Minimum SOA z-scores, calculated after factoring out the influence of these factors, were virtually identical in the two control groups, as were response times (RTs) and dyad ratios (the proportion of hits occurring in dyads). Experiment 2 measured the test-retest reliability of the DA-PASAT in 44 young subjects who underwent three test sessions at weekly intervals. High intraclass correlation coefficients (ICCs) were found for minSOAs (0.87), response times (0.76), and dyad ratios (0.87). Performance improved across test sessions for all measures. Experiment 3 investigated the effects of simulated malingering in 50 subjects: 42% of simulated malingerers produced abnormal (p< 0.05) minSOA z-scores. Simulated malingerers with abnormal scores were distinguished with 87% sensitivity and 69% specificity from control subjects with abnormal scores by excessive differences between training performance and the actual test. Experiment 4 investigated patients with traumatic brain injury (TBI): patients with mild TBI performed within the normal range while patients with severe TBI showed deficits. The DA-PASAT reduces the time and stress of PASAT assessment while gathering sensitive measures of dyad processing that reveal the effects of aging, malingering, and traumatic brain injury on performance.

Normal temporal binding window but no sound-induced flash illusion in people with one eye.

Integrating vision and hearing is an important way in which we process our rich sensory environment. Partial deprivation of the visual system from the loss of one eye early in life results in adaptive changes in the remaining senses (e.g., Hoover et al. in Exp Brain Res 216:565-74, 2012). The current study investigates whether losing one eye early in life impacts the temporal window in which audiovisual events are integrated and whether there is vulnerability to the sound-induced flash illusion. In Experiment 1, we measured the temporal binding window with a simultaneity judgement task where low-level auditory and visual stimuli were presented at different stimulus onset asynchronies. People with one eye did not differ in the width of their temporal binding window, but they took longer to make judgements compared to binocular viewing controls. In Experiment 2, we measured how many light flashes were perceived when a single flash was paired with multiple auditory beeps in close succession (sound induced flash illusion). Unlike controls, who perceived multiple light flashes with two, three or four beeps, people with one eye were not susceptible to the sound-induced flash illusion. In addition, they took no longer to respond compared to both binocular and monocular (eye-patched) viewing controls. Taken together, these results suggest that the lack of susceptibility to the sound-induced flash illusion in people with one eye cannot be accounted for by the width of the temporal binding window. These results provide evidence for adaptations in audiovisual integration due to the reduction of visual input from the loss of one eye early in life.

When Wine and Apple Both Help the Production of Grapes: ERP Evidence for Post-lexical Semantic Facilitation in Picture Naming.

Background: Producing a word in referential naming requires to select the right word in our mental lexicon among co-activated semantically related words. The mechanisms underlying semantic context effects during speech planning are still controversial, particularly for semantic facilitation which investigation remains under-represented in contrast to the plethora of studies dealing with interference. Our aim is to study the time-course of semantic facilitation in picture naming, using a picture-word “interference” paradigm and event-related potentials (ERPs).Methods: We compared two different types of semantic relationships, associative and categorical, in a single word priming and a double word priming paradigm. The primes were presented visually with a long negative Stimulus Onset Asynchrony (SOA), which is expected to cause facilitation.Results: Shorter naming latencies were observed after both associative and categorical primes, as compared to unrelated primes, and even shorter latencies after two primes. Electrophysiological results showed relatively late modulations of waveform amplitudes for both types of primes (beginning ~330 ms post picture onset with a single prime and ~275 ms post picture onset with two primes), corresponding to a shift in latency of similar topographic maps across conditions.Conclusion: The present results are in favor of a post-lexical locus of semantic facilitation for associative and categorical priming in picture naming and confirm that semantic facilitation is as relevant as semantic interference to inform on word production. The post-lexical locus argued here might be related to self-monitoting or/and to modulations at the level of word-form planning, without excluding the participation of strategic processes.

Dissociations of conscious and unconscious perception in TMS-induced blindsight

As with some patients with primary visual cortex (V1) damage, transcranial magnetic stimulation (TMS) over V1 reliably induces blindsight, whereby observers can correctly discriminate the attributes of visual stimuli despite being unable to detect them. This TMS-induced blindsight has been demonstrated to reflect a form of unconscious vision that relies upon different neural pathways than with conscious vision. However, the timing of the neural processes mediating TMS-induced blindsight has been unclear, especially when considering suggestions that TMS interferes with feedback processes to V1 that mediate conscious visual perception. To better elucidate the neural mechanisms that give rise to blindsight, we tested TMS-induced blindsight for the orientation of visual stimuli across a range of stimulus onset asynchronies (SOAs) to assess how different latencies of visual cortex disruption, relative to a visual stimulus, affect detection rates and forced-choice discrimination accuracy. At all TMS latencies, including at SOAs with substantial visual suppression from TMS, discrimination performance was significantly above-chance, demonstrating the consistency of TMS-induced blindsight. Crucially, we observed two windows of maximum visual suppression from TMS at SOAs between 65 and 105 ms, but consistent above-chance discrimination performance accuracy across these windows. However, at longer SOAs, detection and discrimination covaried, suggesting a dependency of discrimination performance on detection only when detection rates exceed threshold levels of normal vision. Taken together, these results indicate that unconscious discrimination occurs independently of detection, including at TMS intervals that optimally interfere with conscious visual perception. They further suggest that forced-choice discrimination is less dependent on feedback processes to V1 than visual awareness and that TMS-induced blindsight is not the same as near-threshold vision.

On the Automaticity of Familiarity in Short-term Recognition: A Test of the Dual-Process Assumption with the PRP Paradigm.

Dual-process models of recognition often assume that one retrieval process, generating a familiarity signal, is automatic, whereas the other, recollection, is controlled. Four experiments are presented to test for automaticity of familiarity in a short-term recognition task. The experiments use the Psychological Refractory Period (PRP) paradigm to assess whether familiarity requires central processing capacity. Task 1 was an oral tone-classification task. Task 2 was a local-recognition task, in which participants decided whether a probe matched a particular item in the memory set, identified by its screen location. Intrusion probes, matching an item of the memory set in a different location, were slower and more difficult to reject than new probes. The size of this intrusion cost reflects the influence of familiarity on recognition. In all four experiments the size of the intrusion cost was additive with the stimulus-onset-asynchrony (SOA) of Task 1 and Task 2, demonstrating that extraction of familiarity requires central capacity. In addition, Experiment 2 showed additive effects of memory set size and serial position with SOA, confirming that recollection, too, requires central capacity. Experiments 3A and 3B compared a condition including new probes to one including only positive and intrusion probes; in the latter condition the familiarity signal was completely uninformative. Participants showed some ability to reduce the influence of familiarity when it was completely uninformative, but only when they were explicitly told to do so (Experiment 3B). To conclude, by one criterion familiarity is a controlled process: It demands central processing capacity. It might also be controlled by another criterion: People can intentionally reduce the influence of familiarity on recognition decision, but they fail to do so spontaneously even when it would be advantageous. All raw data are available on the Open Science Framework: osf.io/7pr72.

Apparent motion perception in lower limb amputees with phantom sensations: “obstacle shunning” and “obstacle tolerance”

Phantom limbs are the phenomenal persistence of postural and sensorimotor features of an amputated limb. Although immaterial, their characteristics can be modulated by the presence of physical matter. For instance, the phantom may disappear when its phenomenal space is invaded by objects (“obstacle shunning”). Alternatively, “obstacle tolerance” occurs when the phantom is not limited by the law of impenetrability and co-exists with physical objects. Here we examined the link between this under-investigated aspect of phantom limbs and apparent motion perception. The illusion of apparent motion of human limbs involves the perception that a limb moves through or around an object, depending on the stimulus onset asynchrony (SOA) for the two images. Participants included 12 unilateral lower limb amputees matched for obstacle shunning (n = 6) and obstacle tolerance (n = 6) experiences, and 14 non-amputees. Using multilevel linear models, we replicated robust biases for short perceived trajectories for short SOA (moving through the object), and long trajectories (circumventing the object) for long SOAs in both groups. Importantly, however, amputees with obstacle shunning perceived leg stimuli to predominantly move through the object, whereas amputees with obstacle tolerance perceived leg stimuli to predominantly move around the object. That is, in people who experience obstacle shunning, apparent motion perception of lower limbs was not constrained to the laws of impenetrability (as the phantom disappears when invaded by objects), and legs can therefore move through physical objects. Amputees who experience obstacle tolerance, however, had stronger solidity constraints for lower limb apparent motion, perhaps because they must avoid co-location of the phantom with physical objects. Phantom limb experience does, therefore, appear to be modulated by intuitive physics, but not in the same way for everyone. This may have important implications for limb experience post-amputation (e.g., improving prosthesis embodiment when limb representation is constrained by the same limits as an intact limb).

A novel co-occurrence-based approach to predict pure associative and semantic priming.

The theoretical "difficulty in separating association strength from [semantic] feature overlap" has resulted in inconsistent findings of either the presence or absence of "pure" associative priming in recent literature (Hutchison, 2003, Psychonomic Bulletin & Review, 10(4), p. 787). The present study used co-occurrence statistics of words in sentences to provide a full factorial manipulation of direct association (strong/no) and the number of common associates (many/no) of the prime and target words. These common associates were proposed to serve as semantic features for a recent interactive activation model of semantic processing (i.e., the associative read-out model; Hofmann & Jacobs, 2014). With stimulus onset asynchrony (SOA) as an additional factor, our findings indicate that associative and semantic priming are indeed dissociable. Moreover, the effect of direct association was strongest at a long SOA (1,000 ms), while many common associates facilitated lexical decisions primarily at a short SOA (200 ms). This response pattern is consistent with previous performance-based accounts and suggests that associative and semantic priming can be evoked by computationally determined direct and common associations.

Trading off switch costs and stimulus availability benefits: An investigation of voluntary task-switching behavior in a predictable dynamic multitasking environment.

In the present study, we introduce a novel, self-organized task-switching paradigm that can be used to study more directly the determinants of switching. Instead of instructing participants to randomly switch between tasks, as in the classic voluntary task-switching paradigm (Arrington & Logan, 2004), we instructed participants to optimize their task performance in a voluntary task-switching environment in which the stimulus associated with the previously selected task appeared in each trial after a delay. Importantly, the stimulus onset asynchrony (SOA) increased further with each additional repetition of this task, whereas the stimulus needed for a task switch was always immediately available. We conducted two experiments with different SOA increments (i.e., Exp. 1a = 50 ms, Exp. 1b = 33 ms) to see whether this procedure would induce switching behavior, and we explored how people trade off switch costs against the increasing availability of the stimulus needed for a task repetition. We observed that participants adapted their behavior to the different task environments (i.e., SOA increments) and that participants switched tasks when the SOA in task switches approximately matched the switch costs. Moreover, correlational analyses indicated relations between individual switch costs and individual switch rates across participants. Together, these results demonstrate that participants were sensitive to the increased availability of switch stimuli in deciding whether to switch or to repeat, which in turn demonstrates flexible adaptive task selection behavior. We suggest that performance limitations in task switching interact with the task environment to influence switching behavior.

Developmental changes in hemispheric processing of ambiguous words during adolescence

Abstract Previous research has provided evidence of a hemispheric asymmetry in processing dominant and subordinate associations of ambiguous words. However, developmental changes of this hemispheric asymmetry have been little studied. We used the divided visual field paradigm to examine the pattern of hemispheric involvement in ambiguity resolution in 31 Hebrew-speaking adolescents and 41 young adults. Participants performed a semantic judgement task on word pairs, where the first word was an ambiguous word (presented centrally) and the second word was related to either its dominant or subordinate meaning (presented laterally after a 750 ms stimulus onset asynchrony). In both groups, no difference was found between the visual fields performance in the dominant meaning condition. However, in the subordinate meaning condition, adolescents (but not adults) responded slower in the left visual field/right hemisphere. These results suggest that the role of RH in the broader semantic search of distant meanings become refined over adolescence, which might be related to the significant development of figurative language during this period. This study may extend the scope of the Fine-Coarse Semantic Coding Theory by including a developmental perspective.

P.3.010 - Imbalance in the deployment of neural resources during visual working memory encoding in schizophrenia as a possible intermediate phenotype

Visual working memory (VWM) deficits are a prominent impairment in patients with schizophrenia (SCZ) and are associated with an inefficient encoding process [1] and with neuronal dysfunctions [2]. Both behavioural and neurofunctional impairments can be observed in unaffected first-degree relatives of patients (REL) as well and are thus discussed as a possible intermediate phenotype of the disorder [3,4]. In this study we investigated the characteristics of WM encoding and its neural substrates in SCZ and REL to evaluate their potential role as an intermediate phenotype of the disorder. We examined n = 25 SCZ, n = 22 REL and n = 25 healthy control subjects (CON). All subjects underwent whole brain fMRI scans in a 3 Tesla MR system. During the fMRI scan, a VWM change-detection task was presented, which showed a sample array consisting of 3 red lines of different orientation that should be memorized. After a delay interval of either 100ms, 400ms or 800ms (SOA = stimulus onset asynchrony) a pattern mask was shown, followed by another delay period and a test array. The longer the delay interval until masking, the more durable the VWM representations were expected to be. Response accuracy served as an estimate of the grade of VWM encoding. The behavioural data was analyzed using a two-way univariate ANOVA with repeated measures and post hoc tests. For group statistics of the event-related fMRI data we conducted a random-effects GLM (RFX-GLM) and a subsequent ANOVA with 'group' as a between-subjects factor (3 levels) and 'SOA' as within-subjects factor (3 levels). For behavioural performance in the VWM task we found significant main effects of 'group' (p = 0.026) and 'SOA' (p = 0.013). The longer the SOA interval, the greater the response accuracy across groups (significant linear trend; p = 0.009). Response accuracy was significantly lower in SCZ compared to CON (p = 0.011) and REL (p = 0.041). We observed aberrant neural activation during VWM encoding for both SCZ and REL compared to CON: across SOA conditions SCZ showed widespread neural deactivation, including the DLPFC and precentral gyrus, as well as increased activity of the anterior cingulate. In REL, we observed a shift in neural activation in regard to the length of the SOA interval: at SOA 100 REL showed only decreased activity in the superior frontal gyrus and fusiform gyrus; at SOA 400 we observed decreased activity in the middle frontal gyrus and increased activity in the superior frontal gyrus; and at SOA 800 REL showed only increased activity in the inferior frontal gyrus. The findings indicate that impaired VWM in SCZ may emerge from an insufficient engagement of the functional WM network with concomitant anterior cingulate hyperactivity during encoding. In REL, the shift from decreased to increased activity might reflect a compensatory process: hypoactivity might point towards fundamental neural dysfunctions—at lighter processing demands local hyperactivity might ensure accurate VWM performance. Neural dysfunctions during VWM encoding should thus be considered as a candidate intermediate phenotype of SCZ.

Improving the Performance of an Auditory Brain-Computer Interface Using Virtual Sound Sources by Shortening Stimulus Onset Asynchrony.

Recently, a brain-computer interface (BCI) using virtual sound sources has been proposed for estimating user intention via electroencephalogram (EEG) in an oddball task. However, its performance is still insufficient for practical use. In this study, we examine the impact that shortening the stimulus onset asynchrony (SOA) has on this auditory BCI. While very short SOA might improve its performance, sound perception and task performance become difficult, and event-related potentials (ERPs) may not be induced if the SOA is too short. Therefore, we carried out behavioral and EEG experiments to determine the optimal SOA. In the experiments, participants were instructed to direct attention to one of six virtual sounds (target direction). We used eight different SOA conditions: 200, 300, 400, 500, 600, 700, 800, and 1,100 ms. In the behavioral experiment, we recorded participant behavioral responses to target direction and evaluated recognition performance of the stimuli. In all SOA conditions, recognition accuracy was over 85%, indicating that participants could recognize the target stimuli correctly. Next, using a silent counting task in the EEG experiment, we found significant differences between target and non-target sound directions in all but the 200-ms SOA condition. When we calculated an identification accuracy using Fisher discriminant analysis (FDA), the SOA could be shortened by 400 ms without decreasing the identification accuracies. Thus, improvements in performance (evaluated by BCI utility) could be achieved. On average, higher BCI utilities were obtained in the 400 and 500-ms SOA conditions. Thus, auditory BCI performance can be optimized for both behavioral and neurophysiological responses by shortening the SOA.

Stimulus duration has little effect on auditory, visual and audiovisual temporal order judgement.

Some classical studies on temporal order judgments (TOJ) suggested a single central process comparing stimulus onsets across modalities. The prevalent current view suggests that there is modality-specific timing estimation followed by a cross-modal stage. If the latter view is correct, TOJ's may vary depending on stimulus modality. Further, if TOJ is based only on onsets, stimulus duration should be irrelevant. To address these issues, we used both unisensory and multisensory stimuli to test whether unisensory duration processing influences cross-modal TOJ's. The stimuli were auditory noise bursts, visual squares, and their cross-modal combinations presented at 10, 40 and 500ms durations, and various stimulus onset asynchronies. Psychometric functions were measured with an identical task in all conditions: On each trial, two stimuli were presented, one to the left, the other to the right of fixation. The participants judged which one started first. TOJ's were little affected by stimulus duration, implying that they are mainly determined by stimulus onsets. Throughout, the cross-modal just noticeable differences were larger than the unisensory ones. In accordance with the current view, our results suggest that cross-modal TOJ's require a comparison of timing after modality-specific estimations.

Simultaneous odour-face presentation strengthens hedonic evaluations and event-related potential responses influenced by unpleasant odour

Odours alter evaluations of concurrently presented visual stimuli, such as faces. Stimulus onset asynchrony (SOA) is known to affect evaluative priming in various sensory modalities. However, effects of SOA on odour priming of visual stimuli are not known. The present study aimed to analyse whether subjective and cortical activation changes during odour priming would vary as a function of SOA between odours and faces.Twenty-eight participants rated faces under pleasant, unpleasant, and no-odour conditions using visual analogue scales. In half of trials, faces appeared one-second after odour offset (SOA 1). In the other half of trials, faces appeared during the odour pulse (SOA 2). EEG was recorded continuously using a 128-channel system, and event-related potentials (ERPs) to face stimuli were evaluated using statistical parametric mapping (SPM).Faces presented during unpleasant-odour stimulation were rated significantly less pleasant than the same faces presented one-second after offset of the unpleasant odour. Scalp-time clusters in the late-positive-potential (LPP) time-range showed an interaction between odour and SOA effects, whereby activation was stronger for faces presented simultaneously with the unpleasant odour, compared to the same faces presented after odour offset.Our results highlight stronger unpleasant odour priming with simultaneous, compared to delayed, odour-face presentation. Such effects were represented in both behavioural and neural data. A greater cortical and subjective response during simultaneous presentation of faces and unpleasant odour may have an adaptive role, allowing for a prompt and focused behavioural reaction to a concurrent stimulus if an aversive odour would signal danger, or unwanted social interaction.

Does hearing aid use affect audiovisual integration in mild hearing impairment?

There is converging evidence for altered audiovisual integration abilities in hearing-impaired individuals and those with profound hearing loss who are provided with cochlear implants, compared to normal-hearing adults. Still, little is known on the effects of hearing aid use on audiovisual integration in mild hearing loss, although this constitutes one of the most prevalent conditions in the elderly and, yet, often remains untreated in its early stages. This study investigated differences in the strength of audiovisual integration between elderly hearing aid users and those with the same degree of mild hearing loss who were not using hearing aids, the non-users, by measuring their susceptibility to the sound-induced flash illusion. We also explored the corresponding window of integration by varying the stimulus onset asynchronies. To examine general group differences that are not attributable to specific hearing aid settings but rather reflect overall changes associated with habitual hearing aid use, the group of hearing aid users was tested unaided while individually controlling for audibility. We found greater audiovisual integration together with a wider window of integration in hearing aid users compared to their age-matched untreated peers. Signal detection analyses indicate that a change in perceptual sensitivity as well as in bias may underlie the observed effects. Our results and comparisons with other studies in normal-hearing older adults suggest that both mild hearing impairment and hearing aid use seem to affect audiovisual integration, possibly in the sense that hearing aid use may reverse the effects of hearing loss on audiovisual integration. We suggest that these findings may be particularly important for auditory rehabilitation and call for a longitudinal study.

Morphological structure mediates the notional meaning of gender marking: Evidence from the gender-congruency effect in Hebrew speech production.

This study investigated the gender-congruency effect of animate nouns in Hebrew. The Picture-Word Interference paradigm was used to manipulate gender congruency between target pictures and spoken distractors. Naming latency revealed an inhibitory gender-congruency effect, as naming the pictures took longer in the presence of a gender-congruent distractor than with a distractor from a different gender category. The inhibitory effect was demonstrated for feminine (morphologically marked) nouns, across two stimulus-onset asynchronies (SOAs) (Experiments 1a and 1b), and masculine (morphologically unmarked) nouns (Experiment 2). The same pattern was observed when participants had to produce bare nouns (Experiment 1) or gender-marked noun phrases (Experiment 3). The inhibitory pattern of the effect resembles previous findings of bare nouns in a subset of Romance languages, including Italian and Spanish. These findings add to previous research which investigated the gender-congruency effect of inanimate nouns, where no effect of gender-congruent words was found. The results are discussed in relation to the null effect previously found for inanimate nouns. The comparison of the present and previous studies is motivated by a common linguistic distinction between animate and inanimate nouns in Hebrew, which ascribes grammatical gender specifications to derivational structures (for inanimate nouns) versus inflectional structures (for animate nouns). Given the difference in the notional meaning of gender specification for animate and inanimate nouns, the case of Hebrew exemplifies how language-specific characteristics, such as rich morphological structures, can be used by the linguistic system to express conceptual distinctions at the form-word level.

Theta and Alpha Oscillations in Attentional Interaction during Distracted Driving.

Performing multiple tasks simultaneously usually affects the behavioral performance as compared with executing the single task. Moreover, processing multiple tasks simultaneously often involve more cognitive demands. Two visual tasks, lane-keeping task and mental calculation, were utilized to assess the brain dynamics through 32-channel electroencephalogram (EEG) recorded from 14 participants. A 400-ms stimulus onset asynchrony (SOA) factor was used to induce distinct levels of attentional requirements. In the dual-task conditions, the deteriorated behavior reflected the divided attention and the overlapping brain resources used. The frontal, parietal and occipital components were decomposed by independent component analysis (ICA) algorithm. The event- and response-related theta and alpha oscillations in selected brain regions were investigated first. The increased theta oscillation in frontal component and decreased alpha oscillations in parietal and occipital components reflect the cognitive demands and attentional requirements as executing the designed tasks. Furthermore, time-varying interactive over-additive (O-Add), additive (Add) and under-additive (U-Add) activations were explored and summarized through the comparison between the summation of the elicited spectral perturbations in two single-task conditions and the spectral perturbations in the dual task. Add and U-Add activations were observed while executing the dual tasks. U-Add theta and alpha activations dominated the posterior region in dual-task situations. Our results show that both deteriorated behaviors and interactive brain activations should be comprehensively considered for evaluating workload or attentional interaction precisely.

Covert Exogenous Cross-Modality Orienting between Audition and Vision

Control of visual attention by auditory stimuli is explored in seven previously unpublished experiments that were presented at conferences in the late 1980s. Reaction time (RT) to luminance targets was found to be affected by the spatial congruence between the target and a preceding or simultaneous, and non-informative, auditory event, suggesting that localizable auditory stimuli exogenously (rapidly and automatically) capture visual attention. These cuing effects were obtained in the absence of eye movements and do not appear to be mediated merely by criterion adjustments. When the information value of the auditory event was placed in conflict with its location (i.e., a tone on the right indicated that the visual target was likely to appear on the left), it was found that at short stimulus onset asynchronies (SOAs) reaction time (RT) was faster for targets at the stimulated location, an effect that disappeared within 500 ms and was reversed by 1000 ms. This demonstrates that it requires over 500 ms for endogenous orienting in response to probabilistic information about target location to overcome the powerful exogenous control of visual attention by localizable auditory stimulation. Simple RT to auditory stimuli was unaffected by the spatial congruence of a preceding or simultaneous visual stimulus. When uninformative, neither pitch contours (rising/falling tones) nor pitch (high/low tones) produced significant visual orienting along the vertical midline. When the direction of a pitch contour indicated the likely location of a visual target, participants were able to shift their attention if the relation between the natural meaning and the probabilistic information was compatible (e.g., rising contour signaled that a upper target was likely) but not when it was incompatible. The relation of these 30-year-old experiments to contemporary findings and ideas is discussed.

Attentional Bias to Beauty with Evolutionary Benefits: Evidence from Aesthetic Appraisal of Landscape Architecture.

Substantial evidence suggests that beauty is associated with the survival and reproduction of organisms. Landscape architecture is composed of a series of natural elements that have significant evolutionary implications. The present study used one pilot material ratings and three experiments to examine the mechanisms of aesthetic appraisals of landscape architecture. The results confirmed that landscape architecture elicited a sense of beauty and captured visual attention more easily than other types of architecture during explicit aesthetic rating task (Experiment 1) and implicit aesthetic perception task (dot-probe paradigm, Experiment 2). Furthermore, the spatial cueing paradigm revealed that response latencies were significantly faster for landscape architecture than non-landscape architecture on valid trials, but there was no significant difference in this contrast on invalid trials at 150-ms stimulus onset asynchrony (SOA, Experiment 3a). At 500-ms SOA (Experiment 3b), participants responded significantly faster for landscape architecture on valid trials, but reacted significantly slower for landscape architecture on invalid trials. The findings indicated that the beauty of landscape architecture can be perceived implicitly, and only faster orienting of attention, but not delayed disengagement of attention was generated at early stages of the processing of landscape architecture. However, the attentional bias at later stages of attentional processes may be resulted from both faster orienting of attention and delayed disengagement of attention from landscape architecture photographs.

Who is more flexible?—Awareness of changing context but not working memory capacity modulates inhibitory control

The present study examines how a person's working memory capacity (WMC) and awareness of change in context influences modulating inhibitory control. Context was manipulated by changing the predictive validity of a prime to a following target (i.e., the proportion of prime repetition) across three phases in a single-prime negative priming task. The prime was a distractor for the following target when the proportion was 25% (in the first and third phases) and a useful cue when the proportion rose to 75% (in the second phase). Participants' WMCs were measured and whether they were aware of the change of the prime-repetition proportion was determined in interviews at the end of the experiment. We found that when the stimulus-onset asynchrony (SOA) was short (Experiment 1), participants aware of the change of prime-repetition proportion showed a null negative priming effect when the contingency increased from 25% to 75%, and then rebooted the effect when it decreased back to 25%, thus indicating an ability to modulate inhibitory control as context varied. In contrast, the unaware participants kept inhibiting primes all the time. When SOA was long (Experiment 2), participants with awareness even showed a positive priming effect when the prime-repetition proportion increased. Surprisingly, participants' WMCs did not matter except for the conscious strategy used in the long-SOA condition. This is the first study simultaneously investigating how WMC and awareness can affect people's ability to modulate inhibitory control and reveals that awareness plays a more direct role in such modulation than does WMC.