Detectability of use errors in summative usability tests of medical devices: Impact of the test environment.

The regulations on summative usability evaluations of medical devices (MDs) emphasize that the test environment must have sufficient ecological validity for generalization to real-life use. Here, we examined the influence of environmental fidelity (a component of ecological validity) on the detectability of MD use errors. A total of 140 participants participated in a summative usability evaluation of an anaphylactic shock auto-injector device under either a high-fidelity condition or a condition acceptable from the manufacturer's perspective, lower-fidelity condition. The numbers of errors detected in each condition were compared by applying descriptive statistics and logistic and Poisson multivariate regressions. We found that the level of fidelity did not influence the overall number of use errors detected but did influence the detection of certain use errors. To optimize the test environment and increase the detection of use errors, each environmental feature's role in the test task should first be examined.

Citizens' Participation in Health and Scientific Research in Switzerland.

Understanding motivation and resistance factors affecting citizen participation in health and scientific research allows to find solutions to improve citizen engagement and interest in science. Through a survey, we identified the main factors influencing citizens' participation in scientific research, and their wishes to be more informed. Results show that the respondents' reasons to participate in research were altruistic motivations, in line with other studies carried out in developed countries. The main factor influencing the non-participation is the lack of opportunity, highlighting the importance to better inform citizens about ongoing studies.

Waist-to-hip ratio affects female body attractiveness and modulates early brain responses.

This investigation examined the electrophysiological response underlying the visual processing of waist-to-hip ratio (WHR) in female bodies, a characteristic known to affect perceived attractiveness. WHRs of female bodies were artificially adjusted to values of 0.6, 0.7, 0.8 or 0.9. Behavioural ratings of attractiveness of the bodies revealed a preference for WHRs of 0.7 in the overall group of participants, which included both male and female heterosexual individuals. Event-related potentials (ERPs) were then recorded while participants performed a selective attention task involving photographs of female models and scrambled images. Results showed that the P1 (80-120 ms) and N1 (130-170 ms) components situated over posterior brain regions were the earliest components to be modulated by attention and bodies. Interestingly, the vertex-positive potential, occurring between 120-180 ms, produced a greater positivity for WHRs of 0.7 compared to the other ratios. However, this increase was only observed when the body stimuli were attended, while no effect was observed for unattended bodies. These findings provide evidence of an early brain sensitivity to visual attributes that constitute secondary sexual characteristics. Although they are relatively discrete from the point of view of their physical quality, these signs possess strong behavioural significance, producing greater reported attractiveness, likely by conveying the biological meaning that signals good health and greater reproductive success. Our results therefore reveal that attributes associated with sexual attractiveness in female bodies are processed rapidly in the stream of visual processing.

Design of InterFACE: A Tool to Improve Collaborative Work and Decision Making During Rescucitation.

Successful resuscitation requires good teamwork, communication and quick decision-making. The complexity of the situation makes the communication often erratic. As a consequence, improper decisions can be taken and errors can occur, endangering patients. In order to support the resuscitation team in their work, we developed an innovative product named Interconnected and Focused Mobile Applications on Patients Care Environment (InterFACE), enhancing team situational awareness, and improving the team communication process. To develop our solution, we relied on a user-centred design process involving caregivers from both adult and paediatric emergency departments. The process started with interviews and observations, followed by an iterative development approach validated at each step by end-users. The resulting intervention is composed of a tablet app interacting with a large screen, visible to each members of the resuscitation team, presenting real time information about the resuscitation. Resuscitations are very complex and challenging situations involving many actors. Designing a support tool for such situations requires a strong involvement of end users to understand how people work together and what information they share.

Electrophysiological evidence of perceived sexual attractiveness for human female bodies varying in waist-to-hip ratio.

The dynamics of brain activation reflecting attractiveness in humans are unclear. Among the different features affecting attractiveness of the female body, the waist-to-hip ratio (WHR) is considered to be crucial. To date, however, no event-related potential (ERP) study has addressed the question of its associated pattern of brain activation. We carried out two different experiments: (a) a behavioural study, to judge the level of attractiveness of female realistic models depicting 4 different WHRs (0.6, 0.7, 0.8, 0.9) with and without clothes; (b) an EEG paradigm, to record brain activity while participants (heterosexual men and women) viewed these same models. Behavioural results showed that WHRs of 0.7 were considered more attractive than the others. ERP analyses revealed a different pattern of activation for male and female viewers. The 0.7 ratio elicited greater positivity at the P1 level in male viewers but not females. Naked bodies increased the N190 in both groups and peaked earlier for the 0.7 ratio in the male viewers. Finally, the late positive component (LPC) was found to be greater in male than in female viewers and was globally more marked for naked bodies as well as WHRs of 0.7 in both groups of viewers. These results provide the first electrophysiological evidence of specific time periods linked to the processing of a body feature denoting attractiveness and therefore playing a role in mate choice.

Usability Validation of Medical Devices: Issues in Identifying Potential Use Errors.

In order to prevent use errors with their medical devices, manufacturers have to integrate a safety-oriented usability engineering process in their product development lifecycle. A critical step of this process is the identification of potential use-errors. Standards and guidelines recommend to triangulate several sources of information e.g. scientific literature, incident reports, manufacturer's files and user's feedbacks. This paper presents lessons learned from applying these recommendations during an international project. We identify issues with (i) searching literature and databases, and (ii) interpreting collected data. Nevertheless triangulation of information sources allows to identify different types of use errors therefore providing valuable lists of potential use errors. Issuing recommendations aim at making easier this critical task.

Processing of masked and unmasked emotional faces under different attentional conditions: an electrophysiological investigation.

In order to investigate the interactions between non-spatial selective attention, awareness and emotion processing, we carried out an ERP study using a backward masking paradigm, in which angry, fearful, happy, and neutral facial expressions were presented, while participants attempted to detect the presence of one or the other category of facial expressions in the different experimental blocks. ERP results showed that negative emotions enhanced an early N170 response over temporal-occipital leads in both masked and unmasked conditions, independently of selective attention. A later effect arising at the P2 was linked to awareness. Finally, selective attention was found to affect the N2 and N3 components over occipito-parietal leads. Our findings reveal that (i) the initial processing of facial expressions arises prior to attention and awareness; (ii) attention and awareness give rise to temporally distinct periods of activation independently of the type of emotion with only a partial degree of overlap; and (iii) selective attention appears to be influenced by the emotional nature of the stimuli, which in turn impinges on unconscious processing at a very early stage. This study confirms previous reports that negative facial expressions can be processed rapidly, in absence of visual awareness and independently of selective attention. On the other hand, attention and awareness may operate in a synergistic way, depending on task demand.

Direction of Biological Motion Affects Early Brain Activation: A Link with Social Cognition.

A number of EEG studies have investigated the time course of brain activation for biological movement over this last decade, however the temporal dynamics of processing are still debated. Moreover, the role of direction of movement has not received much attention even though it is an essential component allowing us to determine the intentions of the moving agent, and thus permitting the anticipation of potential social interactions. In this study, we examined event-related responses (ERPs) in 15 healthy human participants to light point walkers and their scrambled counterparts, whose movements occurred either in the radial or in the lateral plane. Compared to scrambled motion (SM), biological motion (BM) showed an enhanced negativity between 210 and 360ms. A source localization algorithm (sLORETA) revealed that this was due to an increase in superior and middle temporal lobe activity. Regarding direction, we found that radial BM produced an enhanced P1 compared to lateral BM, lateral SM and radial SM. This heightened P1 was due to an increase in activity in extrastriate regions, as well as in superior temporal, medial parietal and medial prefrontal areas. This network is known to be involved in decoding the underlying intentionality of the movement and in the attribution of mental states. The social meaning signaled by the direction of biological motion therefore appears to trigger an early response in brain activity.

Emotional expressions modulate low α and ß oscillations in a cortically blind patient.

Studies of cortical blindness have suggested that some residual visual function may persist without perceptual awareness, a condition known as blindsight. To investigate electrophysiological evidence of unconscious processing of emotional stimuli, we examined the event-related oscillations (EROs) in a 62year-old male patient (TN) with affective blindsight during random stimulation of three facial expressions (fearful, happy and neutral). Spectral power analysis in response to the different emotions revealed significant differences between fearful and happy faces over the right frontal regions at 7-8Hz (low α), and between emotional and neutral faces over the left frontal sites at 12-13Hz (low ß) in a time period between 100-400ms after visual stimulus onset. These results demonstrate that emotional face processing occurs very early in time in the absence of any functional striate cortex, and further reveals the existence of specific oscillatory frequencies that reflect unconscious processing of facial expressions in affective blindsight.

Basic instinct undressed: early spatiotemporal processing for primary sexual characteristics.

This study investigates the spatiotemporal dynamics associated with conscious and non-conscious processing of naked and dressed human bodies. To this effect, stimuli of naked men and women with visible primary sexual characteristics, as well as dressed bodies, were presented to 20 heterosexual male and female participants while acquiring high resolution EEG data. The stimuli were either consciously detectable (supraliminal presentations) or were rendered non-conscious through backward masking (subliminal presentations). The N1 event-related potential component was significantly enhanced in participants when they viewed naked compared to dressed bodies under supraliminal viewing conditions. More importantly, naked bodies of the opposite sex produced a significantly greater N1 component compared to dressed bodies during subliminal presentations, when participants were not aware of the stimulus presented. A source localization algorithm computed on the N1 showed that the response for naked bodies in the supraliminal viewing condition was stronger in body processing areas, primary visual areas and additional structures related to emotion processing. By contrast, in the subliminal viewing condition, only visual and body processing areas were found to be activated. These results suggest that naked bodies and primary sexual characteristics are processed early in time (i.e., <200 ms) and activate key brain structures even when they are not consciously detected. It appears that, similarly to what has been reported for emotional faces, sexual features benefit from automatic and rapid processing, most likely due to their high relevance for the individual and their importance for the species in terms of reproductive success.

Attentional modulation of early ERP components in response to faces: evidence from the attentional blink paradigm.

The attentional blink (AB) is a transient attentional deficit that occurs when two stimuli that must both be detected are presented within an interval of less than 500 ms. Event-related potential (ERP) investigations have suggested that the AB affects a specific component, the P3, which is suppressed when targets are blinked. In view of the link between the P3 and working memory, it has been suggested that the AB might be due to the inability of the blinked target to access working memory. Interestingly, it seems that faces, due to their saliency, might escape the AB effect when cross-category detection is required (i.e., when the targets are composed of faces versus other categories of stimuli). In the present study we investigated this phenomenon in an event-related potential (ERP) study using upright and inverted faces as targets. In a first task, the participants were asked to identify two successive targets, the first composed of geometric shapes and the second of upright or inverted faces. A second control task, identical to the first was also performed, in which only the second targets had to be identified in order to compare ERPs. ERPs and scalp topographies of physically identical sequences of events, differing only by the attentional involvement, were thus compared. Behavioural results showed that faces indeed escape the AB while inverted faces do not. However, the electrophysiological findings showed that when attention was engaged in a previous stimulus (at the shortest lag times), both upright and inverted faces showed a decreased amplitude in the 150-260 ms time period, in addition to a lower P3. At longer lags, when the AB was no longer observed, no ERP differences were found. Our data demonstrate that, although faces escape the attentional blink, previous attentional involvement occurs much earlier than described for other categories of stimuli. This suggests that faces are subjected to an early selection which might allow rapid re-allocation of attention to the stimulus if it is deemed meaningful.

Electrical neuroimaging evidence that spatial frequency-based selective attention affects V1 activity as early as 40-60 ms in humans.

BACKGROUND: Karns and Knight (2009) 1 demonstrated by using ERP and gamma band oscillatory responses that intermodal attention modulates visual processing at the latency of the early phase of the C1 response (62-72 ms) thought to be generated in the primary visual cortex. However, the timing of attentional modulation of visual cortex during object-based attention remains a controversial issue. RESULTS: In this study, EEG recording and LORETA source reconstruction were performed. A large number of subjects (29) and of trial repetitions were used (13,312). EEG was recorded from 128 scalp sites at a sampling rate of 512 Hz. Four square-wave gratings (0.75, 1.5, 3, 6 c/deg) were randomly presented in the 4 quadrants of the visual field. Participants were instructed to pay conjoined attention to a given stimulus quadrant and spatial frequency. The C1 and P1 sensory-evoked components of ERPs were quantified by measuring their mean amplitudes across time within 5 latency ranges 40-60, 60-80, 80-100, 100-120 and 120-140 ms. CONCLUSIONS: Early attention effects were found in the form of an enhanced C1 response (40-80 ms) to frequency-relevant gratings. LORETA, within its spatial resolution limits, identified the neural generators of this effect in the striate cortex (BA17), among other areas.

A no-go related prefrontal negativity larger to irrelevant stimuli that are difficult to suppress.

BACKGROUND: There is a wide debate in the literature about whether N2/P3 effects in no-go trials reflect the inhibition of an intended action, or the absence of a negative movement-related potential typical of go trials. The aim of this study was to provide an objective measure of the suppression of irrelevant information (in a conjoined selective visual attention task) under conditions that were perfectly comparable from the viewpoint of the motoric processes involved. METHODS: Twenty-nine right-handed students took part in the study. Their EEGs were recorded from 128 scalp sites while they viewed gratings of four different spatial frequencies (from 0.75 to 6 c/deg) randomly flashed in the four upper and lower quadrants of the visual field. The tasks consisted of attending and responding to a conjunction of spatial frequency and space location. Intermediate frequencies (1.5 and 3 c/deg) acted as distracters or lures. Analysis of the ERPs elicited by the same physical stimulus, close in spatial frequency to the actual target and falling within the attended quadrant (pseudo-target) vs. a non-target location, allowed us to identify the time course and neural bases of brain activation during the suppression of irrelevant information. RESULTS: FAs were on average 9% for pseudo-targets and 0.2% for other types of lures, indicating that the former were more difficult to suppress. Target-related ERP components (occipito/temporal selection negativity, posterior P3b and precentral motor N2) were greater to pseudo-targets than other distracters. A large prefrontal negativity (370-430 ms) was also identified, much larger to pseudo-targets than non-targets (and absent in response to real targets), thus reflecting response inhibition and top-down cognitive control processes. CONCLUSION: A LORETA inverse solution identified the neural generators of this effect in the left dorsolateral prefrontal cortex (DLPF), left and right fusiform gyri and bilateral superior temporal cortices. The tentative hypothesis is advanced that these activations might reflect the modulatory effects exerted by the fronto/temporal circuit for the suppression of irrelevant information.

Processing valence and intensity of infant expressions: the roles of expertise and gender.

Several studies have provided evidence of a women's better accuracy in interpreting emotional states. Despite this difference is generally ascribed to the primary role of female gender in the affective relation with the offspring, to date, little information is available regarding gender differences in the ability to interpret infant facial expressions. In the present study, we examined the roles of gender and expertise in interpreting infant expression in 34 men and women who differed in their experience with infants. Women showed a significantly higher level of decoding accuracy compared to men. Expertise positively affected facial expressions decoding among women only. Our results suggest that in judging emotional facial expressions of infants, there is an interaction of biological (i.e., gender) and cultural factors that is independent of a woman's socioeconomic status.

Dissociating object familiarity from linguistic properties in mirror word reading.

BACKGROUND: It is known that the orthographic properties of linguistic stimuli are processed within the left occipitotemporal cortex at about 150-200 ms. We recorded event-related potentials (ERPs) to words in standard or mirror orientation to investigate the role of visual word form in reading. Word inversion was performed to determine whether rotated words lose their linguistic properties. METHODS: About 1300 Italian words and legal pseudo-words were presented to 18 right-handed Italian students engaged in a letter detection task. EEG was recorded from 128 scalp sites. RESULTS: ERPs showed an early effect of word orientation at ~150 ms, with larger N1 amplitudes to rotated than to standard words. Low-resolution brain electromagnetic tomography (LORETA) revealed an increase in N1 to rotated words primarily in the right occipital lobe (BA 18), which may indicate an effect of stimulus familiarity. N1 was greater to target than to non-target letters at left lateral occipital sites, thus reflecting the first stage of orthographic processing. LORETA revealed a strong focus of activation for this effect in the left fusiform gyrus (BA 37), which is consistent with the so-called visual word form area (VWFA). Standard words (compared to pseudowords) elicited an enhancement of left occipito/temporal negativity at about 250-350 ms, followed by a larger anterior P3, a reduced frontal N400 and a huge late positivity. Lexical effects for rotated strings were delayed by about 100 ms at occipito/temporal sites, and were totally absent at later processing stages. This suggests the presence of implicit reading processes, which were pre-attentive and of perceptual nature for mirror strings. CONCLUSION: The contrast between inverted and standard words did not lead to the identification of a purely linguistic brain region. This finding suggests some caveats in the interpretation of the inversion effect in subtractive paradigms.

Inter-individual differences in the polarity of early visual responses and attention effects.

While there is a general agreement about the sensory properties of the early-latency C1 (P/N80) and P1 components of visual evoked potentials (VEPs), the literature is not consistent about the timing of modulatory attention effects at an early sensory stage for either space- or object-based stimulus features. The aim of this study was to investigate whether inter-individual differences in VEP morphology might affect the nature and polarity of amplitude changes via selective visual attention. EEG was recorded in 20 right-handed individuals while they viewed drawings of familiar objects presented slightly lateralized and performed a categorization task. It consisted in paying attention and responding to a conjunction of space and object features. On the basis of VEP morphology, and independently of task factors, subjects were subdivided in two groups: one group exhibited a prominent N80 and the other a prominent P80 in the same latency range from the same electrode sites. RTs to targets were identical in the two groups, suggesting that morphology was independent of task-related factors. VEP morphology affected the direction and amplitude of spatial and non-spatial attention effects. While attention effects always resulted in increased positivity for the P80 group (at both the C1 and P1 levels), shape relevance was associated with enhanced N80 and P1 responses in the N80 group. These data provide evidence for an inversion of attention effects, in addition to inversion of C1 polarity, in people exhibiting negative C1 at mesial occipital sites.

The emergence of semantic categorization in early visual processing: ERP indices of animal vs. artifact recognition.

BACKGROUND: Neuroimaging and neuropsychological literature show functional dissociations in brain activity during processing of stimuli belonging to different semantic categories (e.g., animals, tools, faces, places), but little information is available about the time course of object perceptual categorization. The aim of the study was to provide information about the timing of processing stimuli from different semantic domains, without using verbal or naming paradigms, in order to observe the emergence of non-linguistic conceptual knowledge in the ventral stream visual pathway. Event related potentials (ERPs) were recorded in 18 healthy right-handed individuals as they performed a perceptual categorization task on 672 pairs of images of animals and man-made objects (i.e., artifacts). RESULTS: Behavioral responses to animal stimuli were ~50 ms faster and more accurate than those to artifacts. At early processing stages (120-180 ms) the right occipital-temporal cortex was more activated in response to animals than to artifacts as indexed by posterior N1 response, while frontal/central N1 (130-160) showed the opposite pattern. In the next processing stage (200-260) the response was stronger to artifacts and usable items at anterior temporal sites. The P300 component was smaller, and the central/parietal N400 component was larger to artifacts than to animals. CONCLUSION: The effect of animal and artifact categorization emerged at ~150 ms over the right occipital-temporal area as a stronger response of the ventral stream to animate, homomorphic, entities with faces and legs. The larger frontal/central N1 and the subsequent temporal activation for inanimate objects might reflect the prevalence of a functional rather than perceptual representation of manipulable tools compared to animals. Late ERP effects might reflect semantic integration and cognitive updating processes. Overall, the data are compatible with a modality-specific semantic memory account, in which sensory and action-related semantic features are represented in modality-specific brain areas.

Gender and parental status affect the visual cortical response to infant facial expression.

This study sought to determine the influence of gender and parental status on the brain potentials elicited by viewing infant facial expressions. We used ERP recording during a judgement task of infant happy/distressed expression to investigate if viewer gender or parental status affects the visual cortical response at various stages of perceptual processing. ERPs were recorded in 38 adults (male/female, parents/non-parents) during processing of infant facial expressions that varied in valence and intensity. All infants were unfamiliar to viewers. The lateral occipital P110 response was much larger in women than in men, regardless of facial expression, thus indicating a gender difference in early visual processing. The occipitotemporal N160 response provided the first evidence of discrimination of expressions of discomfort and distress and demonstrated a significant gender difference within the parent group, thus suggesting a strong interactive influence of genetic predisposition and parental status on the responsivity of visual brain areas. The N245 component exhibited complete coding of the intensity of facial expression, including positive expressions. At this processing stage the cerebral responses of female and male non-parents were significantly smaller than those of parents and insensitive to differences in the intensity of infant suffering. Smaller P300 amplitudes were elicited in mothers versus fathers, especially with infant expressions of suffering. No major group differences were observed in cerebral responses to happy or comfortable expressions. These findings suggest that mere familiarity with infant faces does not explain group differences.

Gender differences in hemispheric asymmetry for face processing.

BACKGROUND: Current cognitive neuroscience models predict a right-hemispheric dominance for face processing in humans. However, neuroimaging and electromagnetic data in the literature provide conflicting evidence of a right-sided brain asymmetry for decoding the structural properties of faces. The purpose of this study was to investigate whether this inconsistency might be due to gender differences in hemispheric asymmetry. RESULTS: In this study, event-related brain potentials (ERPs) were recorded in 40 healthy, strictly right-handed individuals (20 women and 20 men) while they observed infants' faces expressing a variety of emotions. Early face-sensitive P1 and N1 responses to neutral vs. affective expressions were measured over the occipital/temporal cortices, and the responses were analyzed according to viewer gender. Along with a strong right hemispheric dominance for men, the results showed a lack of asymmetry for face processing in the amplitude of the occipito-temporal N1 response in women to both neutral and affective faces. CONCLUSION: Men showed an asymmetric functioning of visual cortex while decoding faces and expressions, whereas women showed a more bilateral functioning. These results indicate the importance of gender effects in the lateralization of the occipito-temporal response during the processing of face identity, structure, familiarity, or affective content.

Blue piglets? Electrophysiological evidence for the primacy of shape over color in object recognition.

The goal of the study was to investigate how the color and shape of visual stimuli are processed when they are conjointly presented and represent real, and familiar, entities for which normal individuals presumably have a specific 'object color knowledge' (e.g., piglets are pink, artichokes are green). There is evidence, from event related potential (ERP) literature on selective attention to color in conjunction with other, arbitrarily related, stimulus dimensions (e.g., geometrical shape), that color is processed faster than shape, and that the processing of shape depends on color relevance. In this study we recorded ERPs from 28 scalp sites in right-handed volunteers performing selective attention tasks to either color or shape of pictures representing familiar objects and animals. The results revealed that the selection of color was faster, and probably less demanding, than that of shape. However, it was also evidenced that the selection of color depended on object shape, but not vice versa. Indeed, in the attend-color condition, the N2 responses were significantly greater when stimulus shape was prototypically associated, rather than unassociated, with the color perceived. Topographical mapping of difference voltages identified the posterior occipito/temporal region of the left hemisphere as the possible locus of conjoined color and shape processing. Overall, the data support object-based attention models.