Psychophysical Analysis Research Articles

Optogenetic Manipulation of Covert Attention in the Nonhuman Primate.

Optogenetics affords new opportunities to interrogate neuronal circuits that control behavior. In primates, the usefulness of optogenetics in studying cognitive functions remains a challenge. The technique has been successfully wielded, but behavioral effects have been demonstrated primarily for sensorimotor processes. Here, we tested whether brief optogenetic suppression of primate superior colliculus can change performance in a covert attention task, in addition to previously reported optogenetic effects on saccadic eye movements. We used an attention task that required the monkey to detect and report a stimulus change at a cued location via joystick release, while ignoring changes at an uncued location. When the cued location was positioned in the response fields of transduced neurons in the superior colliculus, transient light delivery coincident with the stimulus change disrupted the monkey's detection performance, significantly lowering hit rates. When the cued location was elsewhere, hit rates were unaltered, indicating that the effect was spatially specific and not a motor deficit. Hit rates for trials with only one stimulus were also unaltered, indicating that the effect depended on selection among distractors rather than a low-level visual impairment. Psychophysical analysis revealed that optogenetic suppression increased perceptual threshold, but only for locations matching the transduced site. These data show that optogenetic manipulations can cause brief and spatially specific deficits in covert attention, independent of sensorimotor functions. This dissociation of effect, and the temporal precision provided by the technique, demonstrates the utility of optogenetics in interrogating neuronal circuits that mediate cognitive functions in the primate.

Understanding contrast perception in amblyopia: a psychophysical analysis of the ON and OFF visual pathways.

The study aimed to explore potential discrepancies in contrast sensitivity in the ON and OFF visual pathways among individuals with amblyopia compared to controls. Eleven adult amblyopes (26.2 ± 4.4 [SD] years old) and 10 controls (24.6 ± 0.8 years old) with normal or corrected to normal visual acuity (logMAR VA ≤ 0) participated in this study. Using the quick contrast sensitivity function (qCSF) algorithm, we measured balanced CSF which would stimulate the ON and OFF pathways unselectively, and CSFs for increments and decrements that would selectively stimulate the ON and OFF visual pathways. Contrast sensitivity and area under log contrast sensitivity function were extracted for statistical analysis. For the balanced CSF, we found significant interocular differences in sensitivity and area under log contrast sensitivity function in both amblyopes [F(1,10) = 74.992, p < 0.001] and controls [F(1,9) = 35.6, p < 0.001], while such differences were more pronounced in amblyopes than in controls. For increment and decrement CSFs, we found that the increment sensitivity (p = 0.038) and area under log contrast sensitivity function (p = 0.001) were significantly lower than the decrement in the amblyopic eye. Such differences between increment and decrement CSFs were not observed in the fellow eye of the amblyopes or in the controls. There is a subtle difference in the contrast sensitivity of the amblyopic eye when exposed to stimulation in the ON and OFF pathways.

Sufism with the Integration of Humans: Seyyed Hossein Nasr’s Perspective

In this research paper, I aim to explore and discover the relation of Sufism with the integration of humans in the light of Seyyed Hossein Nasr’s view. I will also discuss the fundamental principle of Sufism, the historical development of Sufism, Seyyed Hossein Nasr’s view on Sufism, the spiritual trends in Sufism, Classical as well as the Modern approach to Sufism, and finally Sufi thoughts and Practices. Sufism, which, in my opinion, is a psycho-physical analysis, is a philosophy of love and God-intoxication. Initially, it was ascetic and devotional but later became speculative and doctrinal. It is a path of spiritualism and achievement of purity and gnosis of God. It is a philosophy that is as old as Islam and an essential part of it. The Sufi practice comprises the dogma of love towards God through the love of human beings, purification of the soul, the process of detachment, simplicity, and service to humankind. Most Sufis put an undivided importance on the moral value system and the sacred relation of Murshid (Guide) and Murid (Disciple). If we analyze these principles of Sufism, then it becomes clear that Sufism is a philosophy that promotes communal harmony, peace, tolerance, and co-existence in society. Seyyed Hossein Nasr explains Sufism as the marrow of the bones or the internal aspects of the Islamic revelation is the means par excellence whereby Tawhid is achieved. The integration of human beings implies the awareness of the One and the transformation of the countless in the light of the One. It is, therefore, the full realization of that faith or Iman, which is the fundamental basis of Islam. Philosophy and Progress, Vol#73-74; No#1-2; Jan-Dec 2023 P 113-129

Peripheral signaling pathways contributing to non-histaminergic itch in humans

BackgroundChronic itch (chronic pruritus) is a major therapeutic challenge that remains poorly understood despite the extensive recent analysis of human pruriceptors. It is unclear how the peripheral nervous system differentiates the signaling of non-histaminergic itch and pain.MethodsHere we used psychophysical analysis and microneurography (single nerve fiber recordings) in healthy human volunteers to explore the distinct signaling mechanisms of itch, using the pruritogens β-alanine, BAM 8-22 and cowhage extract.ResultsThe mode of application (injection or focal application using inactivated cowhage spicules) influenced the itch/pain ratio in sensations induced by BAM 8-22 and cowhage but not β-alanine. We found that sensitizing pre-injections of prostaglandin E2 increased the pain component of BAM 8-22 but not the other pruritogens. A-fibers contributed only to itch induced by β-alanine. TRPV1 and TRPA1 were necessary for itch signaling induced by all three pruritogens. In single-fiber recordings, we found that BAM 8-22 and β-alanine injection activated nearly all CM-fibers (to different extents) but not CMi-fibers, whereas cowhage extract injection activated only 56% of CM-fibers but also 25% of CMi-fibers. A “slow bursting discharge pattern” was evoked in 25% of CM-fibers by β-alanine, in 35% by BAM 8-22, but in only 10% by cowhage extract.ConclusionOur results indicate that no labeled line exists for these pruritogens in humans. A combination of different mechanisms, specific for each pruritogen, leads to itching sensations rather than pain. Notably, non-receptor-based mechanisms such as spatial contrast or discharge pattern coding seem to be important processes. These findings will facilitate the discovery of therapeutic targets for chronic pruritus, which are unlikely to be treated effectively by single receptor blockade.

Haidinger’s brushes: Psychophysical analysis of an entoptic phenomenon

Entoptic phenomena are visual artifacts arising from the interaction of light with the specific anatomic structure of the human eye. While they are usually too subtle to actually enable additional visual abilities, their perception can provide indirect information on the physiological conditions of the visual system. Among the most famous ones, Haidinger’s brushes consist in the appearance of a yellowish bow tie perceived in the presence of linearly polarized white light and originate from the particular spatial distribution of dichroic carotenoid molecules forming a sort of embedded radial polarizer in the foveal region. In this work, we develop a compact and versatile optical setup for the psychophysical analysis of the perceptual threshold of such entoptic effect. The tests performed on a group of 113 healthy individuals under conditions of maximum contrast (blue light) reveal the capability to perceive an average polarization degree around 16%. The developed prototype outlines a new optical platform to train the users in the perception of the phenomenon and infer information on the polarization-degree sensitivity of the human visual system.

Using computerised comparative judgement to assess translation

Abstract Translation assessment represents a productive line of research in Translation Studies. An array of methods has been trialled to assess translation quality, ranging from intuitive assessment to error analysis and from rubric scoring to item-based assessment. In this article, we introduce a lesser-known approach to translation assessment called comparative judgement. Rooted in psychophysical analysis, comparative judgement grounds itself on the assumption that humans tend to be more accurate in making relative judgements than in making absolute judgements. We conducted an experiment, as both a methodological exploration and a feasibility investigation, in which novice and experienced judges were recruited to assess English-Chinese translation, using a computerised comparative judgement platform. The collected data were analysed to shed light on the validity and reliability of assessment results and the judges’ perceptions. Our analysis shows that (1) overall, comparative judgement produced valid measures and facilitated judgement reliability, although such results seemed to be affected by translation directionality and judges’ experience, and (2) the judges were generally confident about their decisions, despite some emergent factors undermining the validity of their decision making. Finally, we discuss the use of comparative judgement as a possible method in translation assessment and its implications for future practice and research.

Noradrenergic deficits contribute to apathy in Parkinson's disease through the precision of expected outcomes.

Apathy is a debilitating feature of many neuropsychiatric diseases, that is typically described as a reduction of goal-directed behaviour. Despite its prevalence and prognostic importance, the mechanisms underlying apathy remain controversial. Degeneration of the locus coeruleus-noradrenaline system is known to contribute to motivational deficits, including apathy. In healthy people, noradrenaline has been implicated in signalling the uncertainty of expectations about the environment. We proposed that noradrenergic deficits contribute to apathy by modulating the relative weighting of prior beliefs about action outcomes. We tested this hypothesis in the clinical context of Parkinson's disease, given its associations with apathy and noradrenergic dysfunction. Participants with mild-to-moderate Parkinson's disease (N = 17) completed a randomised double-blind, placebo-controlled, crossover study with 40 mg of the noradrenaline reuptake inhibitor atomoxetine. Prior weighting was inferred from psychophysical analysis of performance in an effort-based visuomotor task, and was confirmed as negatively correlated with apathy. Locus coeruleus integrity was assessed in vivo using magnetisation transfer imaging at ultra-high field 7T. The effect of atomoxetine depended on locus coeruleus integrity: participants with a more degenerate locus coeruleus showed a greater increase in prior weighting on atomoxetine versus placebo. The results indicate a contribution of the noradrenergic system to apathy and potential benefit from noradrenergic treatment of people with Parkinson's disease, subject to stratification according to locus coeruleus integrity. More broadly, these results reconcile emerging predictive processing accounts of the role of noradrenaline in goal-directed behaviour with the clinical symptom of apathy and its potential pharmacological treatment.

Postural Analysis on Manual Pine Resin Collecting Work: Lifting Index and L5/S1 Compression-Shear Forces

Even though pine oleoresin harvesting is labor-intensive forestry work involving manual material handling (especially lifting) and is massively carried out in Indonesia, there is a lack of ergonomics studies on manual pine oleoresin harvesting. This study focused on lifting-related postures in pine oleoresin harvesting. A Three Dimension Static Strength Prediction Program Version 7.1.0 was used to identify the injury risk on the lower back (lumbosacral joint, L5/S1) using biomechanical criteria (compression and shear forces) at extreme postures. Recommended Weight Limit (RWL) and Lifting Index (LI) were calculated for a comprehensive analysis. The exceeding compression and shear forces indicated that the L5/S1 injury risk on oleoresin collecting work (part of oleoresin harvesting) is high. The psychophysical analysis confirmed the findings, as several main postures in this work were categorized as intense manual lifting due to the excessive score of LI. A significant reduction in the L5/S1 compression and shear forces were shown at a simulation using a proposed load threshold (using the calculated RWL). Keywords: biomechanics, ergonomics, forestry work, manual lifting, oleoresin harvesting

The Stevens law and the derivation of sensory perception

The Stevens law, S = k I n , is commonly accepted as a landmark achievement in the field of sensory psychophysics and has been widely applied in food sensory research. The theory effectively links the two parameters of very different nature, the intensity of sensory perception ( S ) and the intensity of physical stimulus ( I ). However, the Stevens law suffers from two major drawbacks. The equation was self-inconsistent in terms of the units, which makes equation questionable in principle. The Stevens law was also found inapplicable when multiple physical stimuli are involved in the perception of a sensory attribute. To solve the first drawback, we propose to replace the absolute stimulation intensity in the Stevens law with a relative intensity, S = k( I / I 0 ) n . The modified Stevens law becomes self-consistent when both sides of the equation are dimensionless and the theory is applicable regardless of the unit of the physical stimulus. To solve the second drawback, a concept of sensory derivation is introduced and so sensory properties can be categorized as primary sensory and derived sensory. The former can be described effectively by the Stevens law, while description of the latter is beyond the applicability of the Stevens law because of the involvement of multiple sensory stimuli or multi level sensory derivation. Furthermore, a sensory hierarch is constructed with sensory perception of different nature at different levels, including the primary sensory at the basic level and derived sensory perception at progressing levels. The modified Stevens law provides a self-consistent model for psychophysical analysis of sensory perception. The proposed sensory hierarchy helps to streamline sensory terms and attributes and may be used as a useful guide in establishing instrumental analysis of sensory perception.

Color discriminability makes over-specification efficient: Theoretical analysis and empirical evidence

A psychophysical analysis of referential communication establishes a causal link between a visual stimulus and a speaker’s perception of this stimulus, and between the speaker’s internal representation and their reference production. Here, I argue that, in addition to visual perception and language, social cognition plays an integral part in this complex process, as it enables successful speaker-listener coordination. This pragmatic analysis of referential communication tries to explain the redundant use of color adjectives. It is well documented that people use color words when it is not necessary to identify the referent; for instance, they may refer to “the blue star” in a display of shapes with a single star. This type of redundancy challenges influential work from cognitive science and philosophy of language, suggesting that human communication is fundamentally efficient. Here, I explain these seemingly contradictory findings by confirming the visual efficiency hypothesis: redundant color words can facilitate the listener’s visual search for a referent, despite making the description unnecessarily long. Participants’ eye movements revealed that they were faster to find “the blue star” than “the star” in a display of shapes with only one star. A language production experiment further revealed that speakers are highly sensitive to a target’s discriminability, systematically reducing their use of redundant color adjectives as the color of the target became more pervasive in a display. It is concluded that a referential expression’s efficiency should be based not only on its informational value, but also on its discriminatory value, which means that redundant color words can be more efficient than shorter descriptions.

M192. SENSITIVITY FOR MOTION IS WEAKENED IN FIRST EPISODE PSYCHOSIS

BackgroundPerceptual spatial suppression is a phenomenon in which the perceived strength of a stimulus in space is reduced when the stimulus is surrounded by other stimuli. For motion perception, two studies so far have suggested that spatial suppression and sensitivity to motion perception is also reduced in patients with schizophrenia.Studies to date have been conducted in patients with chronic schizophrenia, however, whether these abnormalities are present at the onset of the disorder or whether they emerge during the course of the illness has not been examined, and no study has assessed whether these abnormalities are specific to schizophrenia or whether they are present in other psychotic disorders. Furthermore, if reduced spatial suppression and sensitivity for motion in schizophrenia are related to a glutamatergic hypofunction, as suggested by a recent study (Schallmo et al., 2019), these reductions may be more accentuated in patients who fail to respond to first-line antipsychotic treatment.MethodsSample: 33 patients with a first psychotic episode (16 females, age=16.4±0.6) and 17 healthy controls (9 females, age=17.2±0.61). Exclusion criteria for both groups were: intellectual disability according to DSM-V criteria. For healthy controls, exclusion criteria also included having a first degree relative with a history of psychotic disorder, current or past diagnosis of psychiatrics disorders. Instruments: The perceptual test was performed on a tablet, and consisted of a briefly presented grating (small or large) drifted sideways (the direction was chosen at random with equal probability), in which the participant was instructed to report the perceived direction. Clinical assessment at illness onset and 12 week follow-up: Positive and Negative Symptom Scales (PANSS), Kiddie Schedule for Affective Disorders and Schizophrenia, Present and Lifetime version and Structured Clinical Interview for DSM-IV. Non-response to treatment was defined as lack of 50% reduction in PANSS positive or negative scores at 12 weeks, any change in antipsychotics or need for combinations due to lack of clinical response. Psychophysical analysis: Motion sensitivity was estimated independently of lapses of attention, which were assessed by including trials in which the motion stimulus was easily discriminated.ResultsPatients and healthy controls were homogeneous in age (t=-.720, p=,537) and sex (X2=0.38, p=0.542). In patients, mean treatment response rates was 56.5%. Patients had similar scores of positive and negative symptomatology (positive symptoms= 21±7,13; negative symptoms= 18,4±8,18; general symptoms= 40,7±13,07). At 12 weeks 43,8% had a diagnosis of affective psychosis (bipolar disorder, depressive disorder with psychotic symptoms).Patients with a first psychotic episode, regardless of diagnosis or response to treatment, had less motion sensitivity than healthy controls (f=6.397, p=0.0148). No significant differences were found between groups in surround suppression and no significant correlations were observed between spatial suppression and clinical symptoms.DiscussionTo our knowledge, this is the first study to find abnormal motion sensitivity in patients with a first episode of psychosis. Our measure of sensitivity, given that it was not contaminated by lapses, indicates that patients had a genuine motion perception deficit rather than an inability to focus on the task. Our results also suggest that motion sensitivity may not be specific to patients with schizophrenia but may also characterize affective psychoses. Larger studies may be needed to clarify whether there is a relationship between motion sensitivity and severity of symptoms and response to treatment.

Cognitive and Emotional Aspects of Cupping Therapy

Cupping therapy has recently gained public attention and is widely used in many regions. Some patients are resistant to being treated with cupping therapy, as visually unpleasant marks on the skin may elicit negative reactions. This study aimed to identify the cognitive and emotional components of cupping therapy. Twenty-five healthy volunteers were presented with emotionally evocative visual stimuli representing fear, disgust, happiness, neutral emotion, and cupping, along with control images. Participants evaluated the valence and arousal level of each stimulus. Before the experiment, they completed the Fear of Pain Questionnaire-III. In two-dimensional affective space, emotional arousal increases as hedonic valence ratings become increasingly pleasant or unpleasant. Cupping therapy images were more unpleasant and more arousing than the control images. Cluster analysis showed that the response to cupping therapy images had emotional characteristics similar to those for fear images. Individuals with a greater fear of pain rated cupping therapy images as more unpleasant and more arousing. Psychophysical analysis showed that individuals experienced unpleasant and aroused emotional states in response to the cupping therapy images. Our findings suggest that cupping therapy might be associated with unpleasant-defensive motivation and motivational activation. Determining the emotional components of cupping therapy would help clinicians and researchers to understand the intrinsic effects of cupping therapy.

The problem of timely training and retraining of workforce and innovative methods of the problem solution

The subject of the article is urgent due to fast rates of occurrence of new specialities and the corresponding demand for specialists, on the one hand, and long and inefficient cycle of training of a limited number of specialists with lack or small number of new knowledge possessors. The core of the problem is insufficient quantity of specialists in demand training for a long time, exceeding the time of implemented process cycle change. The objective of the research is to define the problem of timely training and retraining of workforce in educational institutions and offer innovative ways of the problem solution. The tasks of the research are to describe traditional educational processes implemented nowadays and determine the existing deficiencies, to define the problem of timely training and retraining of workforce and offer innovative methods of solving the problem of workforce timely training and retraining. The research is based on such methods as the method of data analysis, method of psychophysical analysis, theory of image identification, probability theory and methods of segmentation analysis. The offered and patented innovative methods contribute to improvement of the quality of training by means of optimal combination of complexity of material studied and psychophysiological parameters of trainees and expansion of teacher’s capabilities in efficiency control of training impact. Within the framework of the present article, the objectively existing problem of training and retraining of workforce was stated and innovative methods of its solution that are totally new in the world, technically implementable and applicable in practice were proposed.

Human-Centered Transparency of Grasping via a Robot-Assisted Minimally Invasive Surgery System

In this paper, we investigate the grasping of rigid objects in a unilateral robot-assisted minimally invasive surgery (RAMIS). We define a human-centered transparency that quantifies the natural action and perception in RAMIS. We demonstrate this human-centered transparency analysis for different values of gripper scaling—the scaling between the grasp aperture of the surgeon-side manipulator and the aperture of the surgical instrument grasper. A total of 31 participants performed teleoperated grasping and perceptual assessment of rigid objects in one of three gripper scaling conditions ( fine , normal , and quick , trading off precision and responsiveness). A psychophysical analysis of the variability of the maximal grasping aperture during prehension and of the reported size of the object revealed that under normal and quick (but not under the fine ) gripper scaling conditions, the teleoperated grasping with our system was similar to natural grasping and, therefore, human-centered transparent. We anticipate that using motor control and psychophysics for human-centered optimization of teleoperation control will eventually improve the usability of RAMIS.

Auditory psychophysical analysis of healthy individuals based on audiometry and absolute threshold tests

Psychophysics is one of the most important aspects to assess the auditory behavior in human beings. The present study has been successful in exploring the temporal resolution with respect to auditory stimulus thereby helping in the analysis of the auditory psychophysics in human beings which has been gaining wide acceptance in behavioral research. This research work concentrated on subjects with no known auditory pathological history, both males and females of different age groups, subjects exposed to noise (fabrication industry, chemical industry) and professional basketball players. The subjects were made to undergo conventional Audiometry Test (AT) as well as the Absolute Threshold Test (ATT) developed. A similar pattern was observed in the results of AT across all types of subjects. There were no eminent variations observed other than a characteristic dip between 4000 – 6000 Hz. Hence it was concluded that the AT cannot assess the variations in hearing perception for normal individuals with respect to age, sex and occupational exposure. The Absolute Threshold (ATTh) obtained from the ATT were found to be varying in subjects with respect to age and sex wherein the males had a better ATTh than females. Also ATTh was found to deteriorate with age. ATTh was able to differentiate the hearing perception of the positively conditioned (basketball players) and negatively conditioned (chemical and fabrication industry) subjects thereby proving to be an efficient tool to assess the hearing perception in the conditioned and the control set of subjects. Hence ATT based approach could be very useful in sports training and rehabilitation approaches and hence can be a very useful tool in the assessment of auditory temporal resolution of human beings in various applications.

Electro-tactile stimulation (ETS) enhances cochlear-implant Mandarin tone recognition.

ObjectiveElectro-acoustic stimulation (EAS) is an effective method to enhance cochlear-implant performance in individuals who have residual low-frequency acoustic hearing. To help the majority of cochlear implant users who do not have any functional residual acoustic hearing, electro-tactile stimulation (ETS) may be used because tactile sensation has a frequency range and perceptual capabilities similar to that produced by acoustic stimulation in the EAS users.MethodsFollowing up the first ETS study showing enhanced English sentence recognition in noise,1 the present study evaluated the effect of ETS on Mandarin tone recognition in noise in two groups of adult Mandarin-speaking individuals. The first group included 11 normal-hearing individuals who listened to a 4-channel, noise-vocoded, cochlear-implant simulation. The second group included 1 unilateral cochlear-implant user and 2 bilateral users with each of their devices being tested independently. Both groups participated in a 4-alternative, forced-choice task, in which they had to identify a tone that was presented in noise at a 0-dB signal-to-noise ratio via electric stimulation (actual or simulated cochlear implants), tactile stimulation or the combined ETS.ResultsWhile electric or tactile stimulation alone produced similar tone recognition (∼40% correct), the ETS enhanced the cochlear-implant tone recognition by 17–18 percentage points. The size of the present ETS enhancement effect was similar to that of the previously reported EAS effect on Mandarin tone recognition. Psychophysical analysis on tactile sensation showed an important role of frequency discrimination in the ETS enhancement.ConclusionTactile stimulation can potentially enhance Mandarin tone recognition in cochlear-implant users who do not have usable residual acoustic hearing. To optimize this potential, high fundamental frequencies need to be transposed to a 100–200 Hz range.

Psychophysical Experience and Heart Rate Analysis in Manual Lifting Task of Malaysian Population

Back pain is one of the prevalent injuries that occurs among Malaysian industrial workers. This is due to manual lifting task. Minimal studies have been conducted to determine the effects of manual lifting on psychophysical experience and heart rate of Malaysian population. The objective of this study is to analyze the psychophysical experience and heart rate of Malaysian in manual lifting task. The lifting task was experimented at various lifting heights (55 cm, 75 cm and 140 cm); loads with masses of 5 kg, 10 kg and 13 kg; and twist angles (0°, 45° and 90°). Six male and six female Malaysian students participated as subjects in the experiment. The Likert Scale was used to evaluate the psychophysical experience; meanwhile the heart rate monitor (Polar FT2, Finland) was applied to measure the heart rate. This study discovered that the psychophysical experience recorded the highest rating when performing lifting test at maximum load mass (13 kg), lifting height of 130 cm, and twist angle of 90°. Furthermore, the subjects experienced the highest heart rate after performing lifting test at maximum lifting height (130 cm) and load mass of 13 kg. This study concluded that the load mass, lifting height, and twist angle are proportional to the level of psychophysical experience. Additionally, when the load mass and lifting height were increased, the heart rate was also increased.

A Psychophysical and EEG Investigation of Cross-Modal Amplitude Modulation

Event Abstract Back to Event A Psychophysical and EEG Investigation of Cross-Modal Amplitude Modulation Justin R. Timora1* and Timothy W. Budd1 1 University of Newcastle, Australia It is well established that both auditory and tactile perceptual processing is dependent on the temporally dynamic features of sensory stimulation. Much less is known about how these temporal features are integrated across sensory modalities. According to the temporal principle of multisensory integration greater cross-modal temporal correspondence should enhance the integration of multisensory stimulation. Aim: Investigate how cross-modal temporal correspondence of amplitude modulation (AM) rate of multimodal presentations of acoustic and vibrotactile AM stimuli influence perceptual sensitivity for both psychophysical and EEG steady state measures of multisensory integration. Method: A psychophysical procedure was used to estimate auditory and vibrotactile AM detection thresholds for a 32 Hz AM target stimuli while the cross-modal modulation rate was varied across six conditions (0, 8, 16, 32, 64 and 128 Hz). In a separate session EEG activity was recorded while participants were presented with the same stimulus conditions. FFT was then used to measure EEG entrainment at the frequency corresponding to AM rate of stimulation. Results: Cross-modal AM rate significantly influenced auditory thresholds with polynomial contrasts indicating a significant quadratic trend. Cross-modal AM rate also significantly influenced vibrotactile thresholds with polynomial contrasts revealing a significant linear trend. Analysis of the 32 Hz SSR activity revealed no significant effect of cross-modal AM rate on the magnitude of 32 Hz SSR activity. Conclusions: Results of the psychophysical analysis suggest that perceptual sensitivity to AM stimuli varied with cross-modal AM rate. Contrary to prior literature, auditory sensitivity was worst when the cross-modal AM rates matched while sensitivity to vibrotactile AM stimuli decreased as the cross-modal AM rate increased. SSR activity was not influenced by cross-modal AM rate suggesting that the oscillatory activity as measured by the SSR may not reflect entrained activity involved in multisensory integration. Keywords: multisensory integration, steady-state responses, temporal processing, amplitude modulation, Temporal correspondence Conference: Australasian Society for Psychophysiology, Inc, Coffs Harbour, Australia, 26 Nov - 28 Nov, 2014. Presentation Type: Oral Presentation Topic: Psychophysiology Citation: Timora JR and Budd TW (2014). A Psychophysical and EEG Investigation of Cross-Modal Amplitude Modulation. Conference Abstract: Australasian Society for Psychophysiology, Inc. doi: 10.3389/conf.fnhum.2014.216.00008 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: 20 Oct 2014; Published Online: 02 Dec 2014. * Correspondence: Mr. Justin R Timora, University of Newcastle, Newcastle, Australia, justin.timora@uon.edu.au 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 Justin R Timora Timothy W Budd Google Justin R Timora Timothy W Budd Google Scholar Justin R Timora Timothy W Budd PubMed Justin R Timora Timothy W Budd 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.

Dissociation of psychophysical and EEG steady-state response measures of cross-modal temporal correspondence for amplitude modulated acoustic and vibrotactile stimulation

Research examining multisensory integration suggests that the correspondence of stimulus characteristics across modalities (cross-modal correspondence) can have a dramatic influence on both neurophysiological and perceptual responses to multimodal stimulation. The current study extends prior research by examining the cross-modal correspondence of amplitude modulation rate for simultaneous acoustic and vibrotactile stimulation using EEG and perceptual measures of sensitivity to amplitude modulation. To achieve this, psychophysical thresholds and steady-state responses (SSRs) were measured for acoustic and vibrotactile amplitude modulated (AM) stimulation for 21 and 40Hz AM rates as a function of the cross-modal correspondence. The study design included three primary conditions to determine whether the changes in the SSR and psychophysical thresholds were due to the cross-modal temporal correspondence of amplitude modulated stimuli: NONE (AM in one modality only), SAME (the same AM rate for each modality) and DIFF (different AM rates for each modality). The results of the psychophysical analysis showed that AM detection thresholds for the simultaneous AM conditions (i.e., SAME and DIFF) were significantly higher (i.e., lower sensitivity) than AM detection thresholds for the stimulation of a single modality (i.e., NONE). SSR results showed significant effects of SAME and DIFF conditions on SSR activity. The different pattern of results for perceptual and SSR measures of cross-modal correspondence of AM rate indicates a dissociation between entrained cortical activity (i.e., SSR) and perception.

Perceptual importance of lighting phenomena in rendering of animated water

Recent years have seen increasing research in perceptually-driven reductions in the costs of realistically rendered imagery. Water is complex and recognizable, and continues to be in the forefront of research. However, the contribution of individual lighting phenomena to the perceived realism of virtual water has not been addressed. All these phenomena have costs associated with their rendering, but does the visual benefit outweigh these costs? This study investigates the human perception of various illumination components found in water-rich virtual environments. The investigation uses a traditional psychophysical analysis to examine viewer perception of these lighting phenomena as they relate to the rendering cost, and ultimately reveals common trends in perceptual value. Five different scenes with a wide range of water and lighting dynamics were tested for perceptual value by one hundred participants. Our results provide an importance comparison for lighting phenomena in the rendering of water, and cost reductions can be made with little or no effect on the perceived quality of the imagery if viewed in a scenario similar to our testing.