Inattentional Blindness: Neural Correlates and Theoretical Progress

Consciousness has remained one of the most perplexing enigmas of science and philosophy. Modern neuroscientific research seeks to understand how consciousness emerges within biological systems through identifying the necessary mechanisms that enable sensory information to be consciously experienced. Inattentional blindness (IB), the failure to notice something right in front of you, offers a profound means of studying consciousness, as it highlights the indistinct boundary between the conscious and the unconscious. The primary goal of the current thesis was to contribute to a scientific understanding of consciousness through advancing knowledge on IB. To this end, two reviews and four empirical studies were conducted. The first review provides a qualitative synthesis of empirical literature on IB that has employed neuroscientific methodology. Findings suggest that neural correlates of consciousness under conditions of IB may favour early sensory views of consciousness, however more research is needed. The second review provides a systematic review of the behavioural literature on IB, with focus on its two leading theories. Findings highlight that no theory can yet fully account for IB, and a model of IB is proposed based on the partial awareness hypothesis. Study one investigates the relation between alpha-band neural activity and IB via electroencephalography (EEG). Results indicate that a reduction in alpha activity in the pre- and post-stimulus interval correlates with consciousness of the critical stimulus during IB. Study two employs transcranial alternating current stimulation (tACS) to examine a causal role of alpha activity in IB. Findings indicate that, relative to control conditions, those stimulated at alpha frequency were more likely to be subject to IB. Study three extends on study two by implementing auditory tone trains at various frequencies during IB. Results show no difference in rates of IB based on auditory tone frequency. Study four then addresses the degree to which semantic processing, as indexed via the N400, can occur under conditions of IB. Findings show that no significant N400 activity is observed when the eliciting stimuli are rendered unconscious via IB. Overall, the implications of the current thesis are that alpha activity has a reliable, and potentially causal, relationship with IB; that a coherent explanation of IB is yet to exist, but may be found in reconsidering the traditional view of visual consciousness more broadly; and that the endowment of meaning to sensory information may be a key function of consciousness

Dying to Win? The Goldman Dilemma in Legend and Fact

One of the implicit justifications for antidoping is that athletes are so committed to winning that they will take performance-enhancing substances regardless of the apparent consequences. Athletes are alleged to be, quite literally, willing to die to win. Support for this claim usually centers on the results of research by physician Bob Goldman, in which athletes were asked to respond to a hypothetical dilemma in which they were offered spectacular success in their chosen sport, but at a heavy price: they would die after five years of glory. In this paper, we examine the origins of this bargain, now popularly referred to as the Goldman dilemma, finding that both the methodology and implications of the original work have repeatedly been described inaccurately in both popular and scientific writings. These errors reflect both poor scholarship and deliberate misuse, where the flawed narrative is used to justify contentious policy decisions

The influence of self-selected music on affect-regulated exercise intensity and remembered pleasure during treadmill running.

This study explored the influence of self-selected music on affect-regulated exercise intensity and Remembered Pleasure. Seventeen active male and female participants (28.1 ±9.9 years; BMI 23.8±3.2 kg/m2; VO2 peak 48.73±8.73 ml.min−1.kg−1) completed a maximal exercise test and each individual’s ventilatory threshold (VT) was identified. Following this, two treadmill exercise trials were performed at an intensity that was perceived to correspond to a Feeling Scale value of +3 (i.e. ‘good’). Sessions with either self-selected music or no music were completed 48 hr apart and in a randomized counterbalanced order. Affective responses (Feeling Scale) and heart rate were measured during exercise and Remembered Pleasure was measured 5-min post exercise. Results indicated that participants selected an exercise intensity that exceeded their VT during the two affect-regulated exercise sessions (p = .002, d = .99). Participants exercised with greater intensity during affect-regulated exercise with music than without (p = .045; d = 1.12) while maintaining a ‘good’ feeling. Furthermore, participants recalled the music session as more pleasurable than the no-music session (p = .001; d = .72). These results illustrate a positive ergogenic and psychological influence of music during affect-regulated exercise. Encouraging individuals to exercise at an intensity that feels ‘good’ elicits an exercise intensity sufficient to garner cardiorespiratory benefits and may lead to improved adherence. Moreover, the use of self-selected music appears to augment this effect. (226 words) Keywords: Affect, exercise, heuristics, remembered utility, physical activit

A Headset Method for Measuring the Visual Temporal Discrimination Threshold in Cervical Dystonia

Background: The visual temporal discrimination threshold (TDT) is the shortest time interval at which one can determine two stimuli to be asynchronous and meets criteria for a valid endophenotype in adult‐onset idiopathic focal dystonia, a poorly penetrant disorder. Temporal discrimination is assessed in the hospital laboratory; in unaffected relatives of multiplex adult‐onset dystonia patients distance from the hospital is a barrier to data acquisition. We devised a portable headset method for visual temporal discrimination determination and our aim was to validate this portable tool against the traditional laboratory‐based method in a group of patients and in a large cohort of healthy controls. Methods: Visual TDTs were examined in two groups 1) in 96 healthy control participants divided by age and gender, and 2) in 33 cervical dystonia patients, using two methods of data acquisition, the traditional table‐top laboratory‐based system, and the novel portable headset method. The order of assessment was randomized in the control group. The results obtained by each technique were compared. Results: Visual temporal discrimination in healthy control participants demonstrated similar age and gender effects by the headset method as found by the table‐top examination. There were no significant differences between visual TDTs obtained using the two methods, both for the control participants and for the cervical dystonia patients. Bland–Altman testing showed good concordance between the two methods in both patients and in controls. Discussion: The portable headset device is a reliable and accurate method for visual temporal discrimination testing for use outside the laboratory, and will facilitate increased TDT data collection outside of the hospital setting. This is of particular importance in multiplex families where data collection in all available members of the pedigree is important for exome sequencing studies

A Comparison of Stimulus Presentation Methods in Temporal Discrimination Testing

The temporal discrimination threshold (TDT) is the shortest time interval at which an individual detects two stimuli to be asynchronous (normal  =  30-50 ms). It has been shown to be abnormal in patients with disorders affecting the basal ganglia including adult onset idiopathic focal dystonia (AOIFD). Up to 97% of patients have an abnormal TDT with age- and sex-related penetrance in unaffected relatives, demonstrating an autosomal dominant inheritance pattern. These findings support the use of the TDT as a pre-clinical biomarker for AOIFD. The usual stimulus presentation method involves the presentation of progressively asynchronous stimuli; when three sequential stimuli are reported asynchronous is taken as a participant\u27s TDT. To investigate the robustness of the \u27staircase\u27 method of presentation, we introduced a method of randomised presentation order to explore any potential \u27learning effect\u27 that may be associated with this existing method. The aim of this study was to investigate differences in temporal discrimination using two methods of stimulus presentation. Thirty healthy volunteers were recruited to the study (mean age 33.73  ±  3.4 years). Visual and tactile TDT testing using a staircase and randomised method of presentation order was carried out in a single session. There was a strong relationship between the staircase and random method for TDT values. This observed consistency between testing methods suggests that the existing experimental approach is a robust method of recording an individual\u27s TDT. In addition, our newly devised randomised paradigm is a reproducible and more efficient method for data acquisition in the clinic setting. However, the two presentation methods yield different absolute TDT results and either of the two methods should be used uniformly in all participants in any one particular study. doi: 10.1088/1361-6579/38/2/N5

Measurement & Analysis of the Temporal Discrimination Threshold Applied to Cervical Dystonia

The temporal discrimination threshold (TDT) is the shortest time interval at which an observer can discriminate two sequential stimuli as being asynchronous (typically 30-50 ms). It has been shown to be abnormal (prolonged) in neurological disorders, including cervical dystonia, a phenotype of adult onset idiopathic isolated focal dystonia. The TDT is a quantitative measure of the ability to perceive rapid changes in the environment and is considered indicative of the behavior of the visual neurons in the superior colliculus, a key node in covert attentional orienting. This article sets out methods for measuring the TDT (including two hardware options and two modes of stimuli presentation). We also explore two approaches of data analysis and TDT calculation. The application of the assessment of temporal discrimination to the understanding of the pathogenesis of cervical dystonia and adult onset idiopathic isolated focal dystonia is also discussed

A realist review of interventions and strategies to promote evidence-informed healthcare: a focus on change agency

Background Change agency in its various forms is one intervention aimed at improving the effectiveness of the uptake of evidence. Facilitators, knowledge brokers and opinion leaders are examples of change agency strategies used to promote knowledge utilization. This review adopts a realist approach and addresses the following question: What change agency characteristics work, for whom do they work, in what circumstances and why?Methods The literature reviewed spanned the period 1997-2007. Change agency was operationalized as roles that are aimed at effecting successful change in individuals and organizations. A theoretical framework, developed through stakeholder consultation formed the basis for a search for relevant literature. Team members, working in sub groups, independently themed the data and developed chains of inference to form a series of hypotheses regarding change agency and the role of change agency in knowledge use.Results 24, 478 electronic references were initially returned from search strategies. Preliminary screening of the article titles reduced the list of potentially relevant papers to 196. A review of full document versions of potentially relevant papers resulted in a final list of 52 papers. The findings add to the knowledge of change agency as they raise issues pertaining to how change agents&rsquo; function, how individual change agent characteristics effect evidence-informed health care, the influence of interaction between the change agent and the setting and the overall effect of change agency on knowledge utilization. Particular issues are raised such as how accessibility of the change agent, their cultural compatibility and their attitude mediate overall effectiveness. Findings also indicate the importance of promoting reflection on practice and role modeling. The findings of this study are limited by the complexity and diversity of the change agency literature, poor indexing of literature and a lack of theory-driven approaches.Conclusion This is the first realist review of change agency. Though effectiveness evidence is weak, change agent roles are evolving, as is the literature, which requires more detailed description of interventions, outcomes measures, the context, intensity, and levels at which interventions are implemented in order to understand how change agent interventions effect evidence-informed health care.<br /

Effects of alternating current voltage amplitude and oxide capacitance on mid-gap interface state defect density extractions in In0.53Ga 0.47As capacitors

This work looks at the effect on mid-gap interface state defect density estimates for In0.53Ga0.47As semiconductor capacitors when different AC voltage amplitudes are selected for a fixed voltage bias step size (100 mV) during room temperature only electrical characterization. Results are presented for Au/Ni/Al2O3/In0.53Ga0.47As/InP metal–oxide–semiconductor capacitors with (1) n-type and p-type semiconductors, (2) different Al2O3 thicknesses, (3) different In0.53Ga0.47As surface passivation concentrations of ammonium sulphide, and (4) different transfer times to the atomic layer deposition chamber after passivation treatment on the semiconductor surface—thereby demonstrating a cross-section of device characteristics. The authors set out to determine the importance of the AC voltage amplitude selection on the interface state defect density extractions and whether this selection has a combined effect with the oxide capacitance. These capacitors are prototypical of the type of gate oxide material stacks that could form equivalent metal–oxide–semiconductor field-effect transistors beyond the 32 nm technology node. The authors do not attempt to achieve the best scaled equivalent oxide thickness in this work, as our focus is on accurately extracting device properties that will allow the investigation and reduction of interface state defect densities at the high-k/III–V semiconductor interface. The operating voltage for future devices will be reduced, potentially leading to an associated reduction in the AC voltage amplitude, which will force a decrease in the signal-to-noise ratio of electrical responses and could therefore result in less accurate impedance measurements. A concern thus arises regarding the accuracy of the electrical property extractions using such impedance measurements for future devices, particularly in relation to the mid-gap interface state defect density estimated from the conductance method and from the combined high–low frequency capacitance–voltage method. The authors apply a fixed voltage step of 100 mV for all voltage sweep measurements at each AC frequency. Each of these measurements is repeated 15 times for the equidistant AC voltage amplitudes between 10 mV and 150 mV. This provides the desired AC voltage amplitude to step size ratios from 1:10 to 3:2. Our results indicate that, although the selection of the oxide capacitance is important both to the success and accuracy of the extraction method, the mid-gap interface state defect density extractions are not overly sensitive to the AC voltage amplitude employed regardless of what oxide capacitance is used in the extractions, particularly in the range from 50% below the voltage sweep step size to 50% above it. Therefore, the use of larger AC voltage amplitudes in this range to achieve a better signal-to-noise ratio during impedance measurements for future low operating voltage devices will not distort the extracted interface state defect density

Menstrual Cycle and the Temporal Discrimination Threshold

The temporal discrimination threshold (TDT) is a proposed pre-clinical biomarker (endophenotype) for adult onset isolated focal dystonia (AOIFD). Age- and sex-related effects on temporal discrimination demonstrate that women, before the age of 40 years, have faster temporal discrimination than men but their TDTs worsen with age at almost three times the rate of men. Thus after 40 years the TDT in women is progressively worse than in men. AOIFD is an increasingly female-predominant disorder after the age of 40; it is not clear whether this age-related sexually-dimorphic difference observed for both the TDT and sex ratio at disease onset in AOIFD is a hormonal or chromosomal effect. The aim of this study was to examine temporal discrimination at weekly intervals during two consecutive menstrual cycles in 14 healthy female volunteers to determine whether physiological hormonal changes affected temporal discrimination. We observed no significant differences in weekly temporal discrimination threshold values during the menstrual cycles and no significant correlation with the menstrual cycle stage. This observed stability of temporal discrimination during cyclical hormonal change raises interesting questions concerning the age-related sexually-dimorphic decline observed in temporal discrimination. Our findings pave the way for future studies exploring potential pathomechanisms for this age-related deterioration