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In classical conditioning, an initially neutral stimulus (conditioned stimulus, CS) becomes associated with a biologically salient event (unconditioned stimulus, US), which might be pain (aversive conditioning) or food (appetitive conditioning). After a few associations, the CS is able to initiate either defensive or consummatory responses, respectively. Contrary to aversive conditioning, appetitive conditioning is rarely investigated in humans, although its importance for normal and pathological behaviors (e.g., obesity, addiction) is undeniable. The present study intents to translate animal findings on appetitive conditioning to humans using food as an US. Thirty-three participants were investigated between 8 and 10 am without breakfast in order to assure that they felt hungry. During two acquisition phases, one geometrical shape (avCS+) predicted an aversive US (painful electric shock), another shape (appCS+) predicted an appetitive US (chocolate or salty pretzel according to the participants' preference), and a third shape (CS) predicted neither US. In a extinction phase, these three shapes plus a novel shape (NEW) were presented again without US delivery. Valence and arousal ratings as well as startle and skin conductance (SCR) responses were collected as learning indices. We found successful aversive and appetitive conditioning. On the one hand, the avCS+ was rated as more negative and more arousing than the CS and induced startle potentiation and enhanced SCR. On the other hand, the appCS+ was rated more positive than the CS and induced startle attenuation and larger SCR. In summary, we successfully confirmed animal findings in (hungry) humans by demonstrating appetitive learning and normal aversive learning.
Names of, for instance, children or companies are often chosen very carefully. They should sound and feel good. Therefore, many companies try to choose artificially created names that can easily be pronounced in various languages. A wide range of psychological research has demonstrated that easy processing (high processing fluency) is intrinsically experienced as positive. Due to this positive feeling, easy processing can have profound influences on preferences for names.
Topolinski, Maschmann, Pecher, and Winkielman (2014) have introduced a different mechanism that influences the perception of words. Across several experiments they found that words featuring consonantal inward wanderings (inward words) were preferred over words featuring consonantal outward wanderings (outward words). They argued that this was due to the fact that approach and avoidance motivations are activated by articulating inward and outward words, because the pronunciation resembles approach and avoidance behaviors of swallowing and spitting, respectively. They suggested this close link as an underlying mechanism for the so-called in-out effect, but did not test this assumption directly.
In the current work, I tested an alternative fluency account of the in-out effect. Specifically, I hypothesized that processing fluency might play a critical role instead of motivational states of approach and avoidance being necessarily activated.
In Chapter 1, I introduce the general topic of my dissertation, followed by a detailed introduction of the research area of approach and avoidance motivations in Chapter 2. In Chapter 3, I narrow the topic down to orally induced approach and avoidance motivations, which is the main topic of my dissertation. In Chapter 4, I introduce the research area of ecological influences on psychological processes. This chapter builds the base for the idea that human language might serve as a source of processing fluency in the in-out effect. In the following Chapter 5, I elaborate the research area of processing fluency, for which I examined whether it plays a role in the in-out effect.
After an overview of my empirical work in Chapter 6, the empirical part starts with Study 1a and Study 1b (Chapter 7) that aimed to show that two languages (Eng. & Ger.) in which the in-out effect has originally been found might feature a source of higher processing fluency for inward over outward words. The results showed that higher frequencies of inward dynamics compared to outward dynamics were found in both languages. This can lead to higher pronunciation fluency for inward compared to outward words which might in turn lay the ground for higher preferences found for inward over outward words.
In Chapter 8, the assumption that inward compared to outward dynamics might be more efficient to process was tested directly in experiments that examined objective as well as subjective processing fluency of artificially constructed non-words featuring pure inward or outward dynamics. Studies 2a-4b found an objective as well as subjective processing advantage for inward over outward words.
In Chapter 9, the causal role of objective and subjective pronunciation fluency in the in-out effect was examined. In Study 5 mediational analyses on item-level and across studies were conducted using objective and subjective fluency as possible mediating variables. In Study 6 mediation analyses were conducted with data on subject- and trial-level from a within-subject design. Overall, the data of the item-based, subject-based and trial-based mediation analyses provide rather mixed results. Therefore, an experimental manipulation of fluency was implemented in the last two studies.
In Chapter 10, Study 7 and Study 8 demonstrate that manipulating fluency experimentally does indeed modulate the attitudinal impact of consonantal articulation direction. Articulation ease was induced by letting participants train inward or outward kinematics before the actual evaluation phase. Additionally, the simulation training was intensified in Study 8 in order to examine whether a stronger modulation of the in-out effect could be found. Training outward words led to an attenuation and, after more extensive training, even to a reversal of the in-out effect, whereas training inward words led to an enhancement of the in-out effect. This hints at my overall hypothesis that the explicit preferences of inward and outward words are, at least partially, driven by processing fluency.
Almost all studies of my dissertation, except for one analysis of the item-based mediation study, speak in favor of the hypothesis that inward words compared to outward words are objectively and subjectively easier to articulate. This possibly contributes partially to a higher preference of inward over outward words. The results are discussed in Chapter 11 with respect to processing fluency and to the role of language as an ecological factor. Finally, future research ideas are elaborated.
Although many researchers refer to organizational culture as the key to explain employees' organizational corruption (= corruption on behalf of the organization), literature lacks systematic empirical evidence. Through a mixed-method approach this research tries to shed some first lights on this issue with the questions: what characteristics describe an organizational culture that promotes employees' corruption? Does a certain type of organizational culture shape a positive attitude towards organizational corruption? Does organizational culture differ in its impact on different types of corruption? Does organizational culture interact with employees’ sex to promote employees’ corruption? And, is there a main effect of sex on corruption?
A qualitative study investigates the characteristics of a corrupt organizational culture in both general and in particular for managers and employees (Study 1). 14 experts of different occupations were asked about underlying assumptions, values, and norms of a corrupt organizational culture coding the frequency and relationship of their answers. The results showed specific underlying assumptions, values, and norms that were shared by the interviewees and provide first insights into their interrelatedness.
In addition, the quantitative field survey (Study 2) analyzed if a corrupt organizational culture shapes a positive attitude towards organizational corruption and if both tangible rewards and lax control mechanism mediate this impact. 131 participants answered questionnaires about their perceived competition in their industry, tangible rewards, lax control mechanism, and their attitude towards both gifting and bribery. Results showed that lax control mechanism (and for gifting also tangible rewards) mediated the positive impact of a corrupt organizational culture on organizational corruption. In addition, men and women did not differ in their attitude towards organizational corruption in a corrupt organizational culture.
Finally a web-based experiment investigates if organizational culture shapes employees' corruption (Study 3). In addition this approach also covers if the impact of organizational culture on corruption depends on the type of corruption (organizational corruption vs. counterproductive), and if employees’ sex influence corruption and if there is an interaction of organizational culture and sex on employees’ corruption. 563 participants had to decide whether they engage in corruption. Although a corrupt organizational culture raises both types of corruption, there was neither a notable main effect of sex nor a high impact interaction effect of both on both types of corruption. Thus, aspects of a corrupt organizational culture seem to influence employees' corruption.
The main prediction of the Uncanny Valley Hypothesis (UVH) is that observation of humanlike characters that are difficult to distinguish from the human counterpart will evoke a state of negative affect. Well-established electrophysiological [late positive potential (LPP) and facial electromyography (EMG)] and self-report [Self-Assessment Manikin (SAM)] indices of valence and arousal, i.e., the primary orthogonal dimensions of affective experience, were used to test this prediction by examining affective experience in response to categorically ambiguous compared with unambiguous avatar and human faces (N = 30). LPP and EMG provided direct psychophysiological indices of affective state during passive observation and the SAM provided self-reported indices of affective state during explicit cognitive evaluation of static facial stimuli. The faces were drawn from well-controlled morph continua representing the UVH' dimension of human likeness (DHL). The results provide no support for the notion that category ambiguity along the DHL is specifically associated with enhanced experience of negative affect. On the contrary, the LPP and SAM-based measures of arousal and valence indicated a general increase in negative affective state (i.e., enhanced arousal and negative valence) with greater morph distance from the human end of the DHL. A second sample (N = 30) produced the same finding, using an ad hoc self-rating scale of feelings of familiarity, i.e., an oft-used measure of affective experience along the UVH' familiarity dimension. In conclusion, this multi-method approach using well-validated psychophysiological and self-rating indices of arousal and valence rejects for passive observation and for explicit affective evaluation of static faces the main prediction of the UVH.
Virtual reality (VR) has made its way into mainstream psychological research in the last two decades. This technology, with its unique ability to simulate complex, real situations and contexts, offers researchers unprecedented opportunities to investigate human behavior in well controlled designs in the laboratory. One important application of VR is the investigation of pathological processes in mental disorders, especially anxiety disorders. Research on the processes underlying threat perception, fear, and exposure therapy has shed light on more general aspects of the relation between perception and emotion. Being by its nature virtual, i.e., simulation of reality, VR strongly relies on the adequate selection of specific perceptual cues to activate emotions. Emotional experiences in turn are related to presence, another important concept in VR, which describes the user's sense of being in a VR environment. This paper summarizes current research into perception of fear cues, emotion, and presence, aiming at the identification of the most relevant aspects of emotional experience in VR and their mutual relations. A special focus lies on a series of recent experiments designed to test the relative contribution of perception and conceptual information on fear in VR. This strand of research capitalizes on the dissociation between perception (bottom up input) and conceptual information (top-down input) that is possible in VR. Further, we review the factors that have so far been recognized to influence presence, with emotions (e.g., fear) being the most relevant in the context of clinical psychology. Recent research has highlighted the mutual influence of presence and fear in VR, but has also traced the limits of our current understanding of this relationship. In this paper, the crucial role of perception on eliciting emotional reactions is highlighted, and the role of arousal as a basic dimension of emotional experience is discussed. An interoceptive attribution model of presence is suggested as a first step toward an integrative framework for emotion research in VR. Gaps in the current literature and future directions are outlined.
Previous research showed that priming effects in the affective misattribution procedure (AMP) are unaffected by direct warnings to avoid an influence of the primes. The present research examined whether a priming influence is diminished by task procedures that encourage accurate judgments of the targets. Participants were motivated to categorize the affective meaning of nonsense targets accurately by being made to believe that a true word was presented in each trial and by providing feedback on (allegedly) incorrect responses. This condition produced robust priming effects. Priming was however reduced and less reliable relative to more typical AMP conditions in which participants guessed the meaning of openly presented nonsense targets. Affective judgments of nonsense targets were not affected by advance knowledge of the response mapping during the priming phase, which argues against a response-priming explanation of AMP effects. These findings show that affective primes influence evaluative judgments even in conditions in which the motivation to provide accurate responses is high and a priming of motor responses is not possible. Priming effects were however weaker with high accuracy motivation, suggesting that a focus on accurate judgments is an effective strategy to control for an unwanted priming influence in the AMP.
The present work comprises four studies dealing with the investigation of the auditory event-related potentials (ERP) Mismatch Negativity (MMN), P300, and N400 under different attentional instructions, and with their application in patients with disorders of consciousness (DOC) to assess residual cognitive functioning. In guided interviews (study 1), practitioners working with DOC patients stated their general interest in and an objective need for the complementation of current diagnostic procedures by reliable and valid ERP-based methods. Subsequently, in study 2, simple oddball and semantic paradigms were applied to 19 behaviorally non-responsive DOC patients revealing the presence of at least one ERP in eight patients investigated. In the third and fourth study, specific attentional effects on ERPs were investigated in healthy participants to define optimal instructions and stimulus parameters. In study 3, MMN and N400 amplitudes were assessed in 18 participants, and in study 4, MMN and P300 amplitudes were assessed in 32 participants. Both studies included an ignore task (attention on simultaneous visual stimuli), a passive task, and a focused task and revealed distinct attentional effects on P300 and N400 with largest amplitudes in the focused task, smaller ones in the passive task and no ERP in the ignore task. An MMN was elicited in all tasks, but still, amplitudes differed as a function of task. In addition, study 4 included oddball paradigms comprising several deviants in different dimensions. Higher amplitudes were found in this multifeature paradigm compared to traditional oddball paradigms and larger amplitudes were elicited by deviants highly different from standards. It is concluded that ERPs represent a promising tool to complement clinical assessment of DOC patients. Application of ERP paradigms should include focused instructions, especially when using semantic material. Furthermore, multifeature paradigms have been proven especially useful eliciting large amplitudes and allowing for the investigation of several dimensions of deviants at the same time.
Brain-computer interfaces (BCIs) are devices that translate signals from the brain into control commands for applications. Within the last twenty years, BCI applications have been developed for communication, environmental control, entertainment, and substitution of motor functions. Since BCIs provide muscle independent communication and control of the environment by circumventing motor pathways, they are considered as assistive technologies for persons with neurological and neurodegenerative diseases leading to motor paralysis, such as amyotrophic lateral sclerosis (ALS), muscular dystrophy, spinal muscular atrophy and stroke (Kübler, Kotchoubey, Kaiser, Wolpaw, & Birbaumer, 2001). Although most researcher mention persons with severe motor impairment as target group for their BCI systems, most studies include healthy participants and studies including potential BCI end-users are sparse. Thus, there is a substantial lack of studies that investigate whether results obtained in healthy participants can be transferred to patients with neurodegenerative diseases. This clearly shows that BCI research faces a translational gap between intense BCI research and bringing BCI applications to end-users outside the lab (Kübler, Mattia, Rupp, & Tangermann, 2013). Translational studies are needed that investigate whether BCIs can be successfully used by severely disabled end-users and whether those end-users would accept BCIs as assistive devices. Another obvious discrepancy exists between a plethora of short-term studies and a sparse number of long-term studies. BCI research thus also faces a reliability gap (Kübler, Mattia, et al., 2013). Most studies present only one BCI session, however the few studies that include several testing sessions indicate high inter- and intra-individual variance in the end-users’ performance due to non-stationarity of signals. Long-term studies, however, are needed to demonstrate whether a BCI can be reliably used as assistive device over a longer period of time in the daily-life of a person. Therefore there is also a great need for reliability studies.
The purpose of the present thesis was to address these research gaps and to bring BCIs closer to end-users in need, especially into their daily-lives, following a user-centred design (UCD). The UCD was suggested as theoretical framework for bringing BCIs to end-users by Kübler and colleagues (Kübler et al., 2014; Zickler et al., 2011). This approach aims at the close and iterative interaction between BCI developers and end-users with the final goal to develop BCI systems that are accepted as assistive devices by end-users. The UCD focuses on usability, that is, how well a BCI technology matches the purpose and meets the needs and requirements of the targeted end-users and was standardized with the ISO 9241-210.
Within the UCD framework, usability of a device can be defined with regard to its effectiveness, efficiency and satisfaction. These aspects were operationalized by Kübler and colleagues to evaluate BCI-controlled applications. As suggested by Vaughan and colleagues, the number of BCI sessions, the total usage duration and the impact of the BCI on the life of the person can be considered as indicators of usefulness of the BCI in long-term daily-life use (Vaughan, Sellers, & Wolpaw, 2012). These definitions and metrics for usability and usefulness were applied for evaluating BCI applications as assistive devices in controlled settings and independent use. Three different BCI applications were tested and evaluated by in total N=10 end-users: In study 1 a motor-imagery (MI) based BCI for gaming was tested by four end-users with severe motor impairment. In study 2, a hybrid P300 event-related (ERP) based BCI for communication was tested by four severely motor restricted end-users with severe motor impairment. Study 1 and 2 are short-term studies conducted in a controlled-setting. In study 3 a P300-ERP BCI for creative expression was installed for long-term independent use at the homes of two end-users in the locked-in state. Both end-users are artists who had gradually lost the ability to paint after being diagnosed with ALS.
Results reveal that BCI controlled devices are accepted as assistive devices. Main obstacles for daily-life use were the not very aesthetic design of the EEG-cap and electrodes (cap is eye-catching and looks medical), low comfort (cables disturb, immobility, electrodes press against head if lying on a head cushion), complicated and time-consuming adjustment, low efficiency and low effectiveness, and not very high reliability (many influencing factors). While effectiveness and efficiency in the MI based BCI were lower compared to applications using the P300-ERP as input channel, the MI controlled gaming application was nevertheless better accepted by the end-users and end-users would rather like to use it compared to the communication applications. Thus, malfunctioning and errors, low speed, and the EEG cap are rather tolerated in gaming applications, compared to communication devices. Since communication is essential for daily-life, it has to be fast and reliable. BCIs for communication, at the current state of the art, are not considered competitive with other assistive devices, if other devices, such as eye-gaze, are still an option. However BCIs might be an option when controlling an application for entertainment in daily-life, if communication is still available. Results demonstrate that BCI is adopted in daily-life if it matches the end-users needs and requirements. Brain Painting serves as best representative, as it matches the artists’ need for creative expression. Caveats such as uncomfortable cap, dependence on others for set-up, and experienced low control are tolerated and do not prevent BCI use on a daily basis. Also end-users in real need of means for communication, such as persons in the locked-in state with unreliable eye-movement or no means for independent communication, do accept obstacles of the BCI, as it is the last or only solution to communicate or control devices. Thus, these aspects are “no real obstacles” but rather “challenges” that do not prevent end-users to use the BCI in their daily-lives. For instance, one end-user, who uses a BCI in her daily-life, stated: “I don’t care about aesthetic design of EEG cap and electrodes nor amplifier”. Thus, the question is not which system is superior to the other, but which system is best for an individual user with specific symptoms, needs, requirements, existing assistive solutions, support by caregivers/family etc.; it is thereby a question of indication. These factors seem to be better “predictors” for adoption of a BCI in daily-life, than common usability criterions such as effectiveness or efficiency. The face valid measures of daily-life demonstrate that BCI-controlled applications can be used in daily-life for more than 3 years, with high satisfaction for the end-users, without experts being present and despite a decrease in the amplitude of the P300 signal. Brain Painting re-enabled both artists to be creatively active in their home environment and thus improved their feelings of happiness, usefulness, self-esteem, well-being, and consequently quality of life and supports social inclusion. This thesis suggests that BCIs are valuable tools for people in the locked-in state.
Anxiety is an affective state characterized by a sustained, long-lasting defensive response, induced by unpredictable, diffuse threat. In comparison, fear is a phasic response to predictable threat. Fear can be experimentally modeled with the help of cue conditioning. Context conditioning, in which the context serves as the best predictor of a threat due to the absence of any conditioned cues, is seen as an operationalization of sustained anxiety.
This thesis used a differential context conditioning paradigm to examine sustained attention processes in a threat context compared to a safety context for the first time. In three studies, the attention mechanisms during the processing of contextual anxiety were examined by measuring heart rate responses and steady-state-visually evoked potentials (ssVEPs). An additional focus was set on the processing of social cues (i.e. faces) and the influence of contextual information on these cues. In a last step, the correlates of sustained anxiety were compared to evoked responses by phasic fear, which was realized in a previously established paradigm combining predictable and unpredictable threat.
In the first study, a contextual stimulus was associated with an aversive loud noise, while a second context remained unpaired. This conditioning paradigm created an anxiety context (CTX+) and a safety context (CTX-). After acquisition, a social agent vs. an object was presented as a distractor in both contexts. Heart rate and cortical responses, with ssVEPs by using frequency tagging, to the contexts and the distractors were assessed. Results revealed enhanced ssVEP amplitudes for the CTX+ compared to the CTX− during acquisition and during presentation of distractor stimuli. Additionally, the heart rate was accelerated in the acquisition phase, followed by a heart rate deceleration as a psychophysiological marker of contextual anxiety.
Study 2 used the same context conditioning paradigm as Study 1. In contrast to the first study, persons with different emotional facial expressions were presented in the anxiety and safety contexts in order to compare the differential processing of these cues within periods of threat and safety. A similar anxiety response was found in the second study, although only participants who
Abstract
VIII
were aware of the contingency between contexts and aversive event showed a sensory amplification of the threat context, indicated by heart rate response and ssVEP activation. All faces irrespective of their emotional expression received increased attentional resources when presented within the anxiety context, which suggests a general hypervigilance in anxiety contexts.
In the third study, the differentiation of predictable and unpredictable threat as an operationalization of fear and anxiety was examined on a cortical and physiological level. In the predictable condition, a social cue was paired with an aversive event, while in the unpredictable condition the aversive event remained unpaired with the respective cue. A fear response to the predictable cue was found, indicated by increased oscillatory response and accelerated heart rate. Both predictable and unpredictable threat yielded increased ssVEP amplitudes evoked by the context stimuli, while the response in the unpredictable context showed longer-lasting ssVEP activation to the threat context.
To sum up, all three studies endorsed anxiety as a long-lasting defensive response. Due to the unpredictability of the aversive events, the individuals reacted with hypervigilance in the anxiety context, reflected in a facilitated processing of sensory information and an orienting response. This hypervigilance had an impact on the processing of novel cues, which appeared in the anxiety context. Considering the compared stimuli categories, the stimuli perceived in a state of anxiety received increased attentional resources, irrespective of the emotional arousal conveyed by the facial expression. Both predictable and unpredictable threat elicited sensory amplification of the contexts, while the response in the unpredictable context showed longer-lasting sensory facilitation of the threat context.
The objective of this study was to test the usability of a new auditory Brain-Computer Interface (BCI) application for communication. We introduce a word based, intuitive auditory spelling paradigm the WIN-speller. In the WIN-speller letters are grouped by words, such as the word KLANG representing the letters A, G, K, L, and N. Thereby, the decoding step between perceiving a code and translating it to the stimuli it represents becomes superfluous. We tested 11 healthy volunteers and four end-users with motor impairment in the copy spelling mode. Spelling was successful with an average accuracy of 84% in the healthy sample. Three of the end-users communicated with average accuracies of 80% or higher while one user was not able to communicate reliably. Even though further evaluation is required, the WIN-speller represents a potential alternative for BCI based communication in end-users.
Several emotion theorists suggest that valenced stimuli automatically trigger motivational orientations and thereby facilitate corresponding behavior. Positive stimuli were thought to activate approach motivational circuits which in turn primed approach-related behavioral tendencies whereas negative stimuli were supposed to activate avoidance motivational circuits so that avoidance-related behavioral tendencies were primed (motivational orientation account). However, recent research suggests that typically observed affective stimulus response compatibility phenomena might be entirely explained in terms of theories accounting for mechanisms of general action control instead of assuming motivational orientations to mediate the effects (evaluative coding account). In what follows, we explore to what extent this notion is applicable. We present literature suggesting that evaluative coding mechanisms indeed influence a wide variety of affective stimulus response compatibility phenomena. However, the evaluative coding account does not seem to be sufficient to explain affective S-R compatibility effects. Instead, several studies provide clear evidence in favor of the motivational orientation account that seems to operate independently of evaluative coding mechanisms. Implications for theoretical developments and future research designs are discussed.
Background
In this study, we evaluated electrooculography (EOG), an eye tracker and an auditory brain-computer interface (BCI) as access methods to augmentative and alternative communication (AAC). The participant of the study has been in the locked-in state (LIS) for 6 years due to amyotrophic lateral sclerosis. He was able to communicate with slow residual eye movements, but had no means of partner independent communication. We discuss the usability of all tested access methods and the prospects of using BCIs as an assistive technology.
Methods
Within four days, we tested whether EOG, eye tracking and a BCI would allow the participant in LIS to make simple selections. We optimized the parameters in an iterative procedure for all systems.
Results
The participant was able to gain control over all three systems. Nonetheless, due to the level of proficiency previously achieved with his low-tech AAC method, he did not consider using any of the tested systems as an additional communication channel. However, he would consider using the BCI once control over his eye muscles would no longer be possible. He rated the ease of use of the BCI as the highest among the tested systems, because no precise eye movements were required; but also as the most tiring, due to the high level of attention needed to operate the BCI.
Conclusions
In this case study, the partner based communication was possible due to the good care provided and the proficiency achieved by the interlocutors. To ease the transition from a low-tech AAC method to a BCI once control over all muscles is lost, it must be simple to operate. For persons, who rely on AAC and are affected by a progressive neuromuscular disease, we argue that a complementary approach, combining BCIs and standard assistive technology, can prove valuable to achieve partner independent communication and ease the transition to a purely BCI based approach. Finally, we provide further evidence for the importance of a user-centered approach in the design of new assistive devices.
Visual ERP (P300) based brain-computer interfaces (BCIs) allow for fast and reliable spelling and are intended as a muscle-independent communication channel for people with severe paralysis. However, they require the presentation of visual stimuli in the field of view of the user. A head-mounted display could allow convenient presentation of visual stimuli in situations, where mounting a conventional monitor might be difficult or not feasible (e.g., at a patient's bedside). To explore if similar accuracies can be achieved with a virtual reality (VR) headset compared to a conventional flat screen monitor, we conducted an experiment with 18 healthy participants. We also evaluated it with a person in the locked-in state (LIS) to verify that usage of the headset is possible for a severely paralyzed person. Healthy participants performed online spelling with three different display methods. In one condition a 5 x 5 letter matrix was presented on a conventional 22 inch TFT monitor. Two configurations of the VR headset were tested. In the first (glasses A), the same 5 x 5 matrix filled the field of view of the user. In the second (glasses B), single letters of the matrix filled the field of view of the user. The participant in the LIS tested the VR headset on three different occasions (glasses A condition only). For healthy participants, average online spelling accuracies were 94% (15.5 bits/min) using three flash sequences for spelling with the monitor and glasses A and 96% (16.2 bits/min) with glasses B. In one session, the participant in the LIS reached an online spelling accuracy of 100% (10 bits/min) using the glasses A condition. We also demonstrated that spelling with one flash sequence is possible with the VR headset for healthy users (mean: 32.1 bits/min, maximum reached by one user: 71.89 bits/min at 100% accuracy). We conclude that the VR headset allows for rapid P300 BCI communication in healthy users and may be a suitable display option for severely paralyzed persons.
Brain-computer interfaces (BCIs) could provide a muscle-independent communication channel to persons with severe paralysis by translating brain activity into device commands. As a means of communication, in particular BCIs based on event-related potentials (ERPs) as control signal have been researched. Most of these BCIs rely on visual stimulation and have been investigated with healthy participants in controlled laboratory environments. In proof-of-principle studies targeted end users gained control over BCI systems; however, these systems are not yet established as an assistive technology for persons who would most benefit from them. The main aim of this thesis is to advance the usability of ERP-BCIs for target users. To this end, five studies with BCIs have been conducted that enabled users to communicate by focusing their attention on external stimuli.
Two studies were conducted in order to demonstrate the advantages and to further improve the practical application of visual BCIs. In the first study, mental workload was experimentally manipulated during prolonged BCI operation. The study showed the robustness of the visual ERP-BCI since users maintained a satisfactory level of control despite constant distraction in the form of background noise. Moreover, neurophysiological markers that could potentially serve as indicators of high mental workload or fatigue were revealed. This is a first step towards future applications in which the BCI could adapt to the mental state of the user (e.g. pauses if high mental workload is detected to prevent false selections). In the second study, a head-mounted display (HMD), which assures that stimuli are presented in the field of view of the user, was evaluated. High accuracies and information transfer rates, similar to a conventional display, were achieved by healthy participants during a spelling task. Furthermore, a person in the locked-in state (LIS) gained control over the BCI using the HMD. The HMD might be particularly suited for initial communication attempts with persons in the LIS in situations, where mounting a conventional monitor is difficult or not feasible.
Visual ERP-BCIs could prove valuable for persons with residual control over eye muscles and sufficient vision. However, since a substantial number of target users have limited control over eye movements and/or visual impairments, BCIs based on non-visual modalities are required. Therefore, a main aspect of this thesis was to improve an auditory paradigm that should enable motor impaired users to spell by focusing attention on different tones. The two conducted studies revealed that healthy participants were able to achieve high spelling performance with the BCI already in the first session and stress the importance of the choice of the stimulus material. The employed natural tones resulted in an increase in performance compared to a previous study that used artificial tones as stimuli. Furthermore, three out of five users with a varying degree of motor impairments could gain control over the system within the five conducted sessions. Their performance increased significantly from the first to the fifth session - an effect not previously observed for visual ERP-BCIs. Hence, training is particularly important when testing auditory multiclass BCIs with potential users.
A prerequisite for user satisfaction is that the BCI technology matches user requirements. In this context, it is important to compare BCIs with already established assistive technology. Thus, the fifth study of this dissertation evaluated gaze dependent methods (EOG, eye tracking) as possible control signals for assistive technology and a binary auditory BCI with a person in the locked-in state. The study participant gained control over all tested systems and rated the ease of use of the BCI as the highest among the tested alternatives, but also rated it as the most tiring due to the high amount of attention that was needed for a simple selection. Further efforts are necessary to simplify operation of the BCI.
The involvement of end users in all steps of the design and development process of BCIs will increase the likelihood that they can eventually be used as assistive technology in daily life. The work presented in this thesis is a substantial contribution towards the goal of re-enabling communication to users who cannot rely on motor activity to convey their thoughts.
Routes to Embodiment
(2015)
Research on embodiment is rich in impressive demonstrations but somewhat poor in comprehensive explanations. Although some moderators and driving mechanisms have been identified, a comprehensive conceptual account of how bodily states or dynamics influence behavior is still missing. Here, we attempt to integrate current knowledge by describing three basic psychological mechanisms: direct state induction, which influences how humans feel or process information, unmediated by any other cognitive mechanism; modal priming, which changes the accessibility of concepts associated with a bodily state; sensorimotor simulation, which affects the ease with which congruent and incongruent actions are performed. We argue that the joint impact of these mechanisms can account for most existing embodiment effects. Additionally, we summarize empirical tests for distinguishing these mechanisms and suggest a guideline for future research about the mechanisms underlying embodiment effects.
The novel BackHome system offers individuals with disabilities a range of useful services available via brain-computer interfaces (BCIs), to help restore their independence. This is the time such technology is ready to be deployed in the real world, that is, at the target end users’ home. This has been achieved by the development of practical electrodes, easy to use software, and delivering telemonitoring and home support capabilities which have been conceived, implemented, and tested within a user-centred design approach. The final BackHome system is the result of a 3-year long process involving extensive user engagement to maximize effectiveness, reliability, robustness, and ease of use of a home based BCI system. The system is comprised of ergonomic and hassle-free BCI equipment; one-click software services for Smart Home control, cognitive stimulation, and web browsing; and remote telemonitoring and home support tools to enable independent home use for nonexpert caregivers and users. BackHome aims to successfully bring BCIs to the home of people with limited mobility to restore their independence and ultimately improve their quality of life.
Die meisten Unfälle mit Personenschaden in der Bundesrepublik Deutschland sind infolge urbaner Verkehrskonflikte zu verzeichnen. Die Mehrzahl dieser Unfälle findet in Kreuzungssituationen statt (sog. Kreuzen-, Einbiege- und Abbiege-Unfälle). Heutige Assistenzsysteme zur Kollisionsvermeidung oder -abschwächung stoßen in diesen Situationen aufgrund der durch bordeigene Fahrzeugsensorik eingeschränkten Möglichkeiten zur Erfassung der Verkehrsumgebung an ihre Grenzen. Diese Einschränkungen ergeben sich beispielsweise durch Sichtverdeckungen (z.B. durch parkende Fahrzeuge oder Häuserreihen, welche die Sicht in Kreuzungsarme verdecken) oder die begrenzte Erfassungsgüte verletzlicher Verkehrsteilnehmer (Fußgänger, Radfahrer oder Motorradfahrer). Zukünftige kooperative Kommunikationstechnologien, basierend auf Fahrzeug-Fahrzeug- und Fahrzeug-Infrastruktur-Kommunikation, ermöglichen es, dem Fahrer auch in komplexen urbanen Konfliktsituationen frühzeitig Informationen über potentielle Gefahrensituationen zu übermitteln. Gleichwohl liegen Konzepte zur Ausgestaltung einer solchen Fahrerunterstützung, die den Fähigkeiten und Bedürfnissen des Fahrers entsprechen, bislang nur vereinzelt vor.
In dieser Arbeit wird deshalb ein neuartiges Konzept zur frühzeitigen Fahrerunterstützung entwickelt und in einer im Fahrsimulator durchgeführten Studienreihe empirisch evaluiert. Ziel ist es, dem Fahrer im Gegensatz zu dringlichen Kollisionswarnungen, wie sie heutzutage beispielsweise im Kontext von Notbremsassistenten verwendet werden, frühzeitig auf drohende Verkehrskonflikte hinzuweisen. Um die Zuverlässigkeit dieser Unterstützung zu erhöhen, soll der Fahrer (1.) so früh wie nötig aber so spät wie möglich, (2.) so spezifisch wie nötig und (3.) so dringlich wie nötig informiert werden. Diese drei zentralen Gestaltungskriterien (Zeitpunkt, Spezifität und Dringlichkeit) wurden in meiner Arbeit in umfassenden Probandenstudien empirisch untersucht, wobei die zu erwartende Unzuverlässigkeit der maschinellen Situationsanalyse und -prädiktion expliziter Bestandteil des Studiendesigns war. Folgende Gestaltungsempfehlungen können, basierend auf den Studienergebnissen, gegeben werden:
Zeitpunkt: Die Fahrerinformationen sollten eine bis zwei Sekunden vor dem letztmöglichen Warnzeitpunkt (t0+1s/2s) präsentiert werden. Noch frühzeitigere Fahrerinformationen führten zu keiner weiteren Wirksamkeitssteigerung. Fahrerinformationen zum letztmöglichen Warnzeitpunkt (t0) hatten keinen positiven Einfluss auf das Fahrverhalten.
Spezifität: Die Fahrerinformationen sollten eine Anzeige der Richtung, aus welcher der Konflikt droht (sog. richtungsspezifische Anzeige), beinhalten. Unspezifische Anzeigen (bloße Anzeige, dass ein Konflikt droht) führten zwar zu vergleichbaren Verhaltenseffekten wie spezifische Anzeigen. Die Anzeige der Konfliktrichtung steigerte jedoch die wahrgenommene Nützlichkeit der Fahrerunterstützung. Falls mit der Ausgabe fehlerhafter Richtungsanzeigen zu rechnen ist, wird dennoch eine unspezifische Anzeigestrategie empfohlen, da fehlerhafte Richtungsanzeigen eine Einschränkung der subjektiven Nützlichkeit zur Folge hatten. Auch die Anzeige der Art des Konfliktpartners führte zu einer höheren subjektiven Nützlichkeit, jedoch berichteten die Fahrer gleichzeitig von einer erhöhten Ablenkungswirkung dieser Anzeigen.
Dringlichkeit: Es sollte ein rein visuelles Anzeigekonzept verwendet werden. Zwar führten dringlichere, visuell-auditive Anzeigen zu einer schnelleren Bremsreaktion als rein visuelle Anzeigen. In Anbetracht der Frühzeitigkeit der Fahrerinformationen war dies zum einen jedoch nicht entscheidend für deren Wirksamkeit. Zum anderen wirkten sich falsche Alarme gerade bei visuell-auditiven Fahrerinformationen negativ auf Bremsreaktion und Wirksamkeit aus.
We used a new methodological approach to investigate whether top-down influences like expertise determine the extent of unconscious processing. This approach does not rely on preexisting differences between experts and novices, but instructs essentially the same task in a way that either addresses a domain of expertise or not. Participants either were instructed to perform a lexical decision task (expert task) or to respond to a combination of single features of word and non-word stimuli (novel task). The stimuli and importantly also the mapping of responses to those stimuli, however, were exactly the same in both groups. We analyzed congruency effects of masked primes depending on the instructed task. Participants performing the expert task responded faster and less error prone when the prime was response congruent rather than incongruent. This effect was significantly reduced in the novel task, and even reversed when excluding identical prime-target pairs. This indicates that the primes in the novel task had an effect on a perceptual level, but were not able to impact on response activation. Overall, these results demonstrate an expertise-based top-down modulation of unconscious processing that cannot be explained by confounds that are otherwise inherent in comparisons between novices and experts.
The increasing importance of environmental friendly and efficient transportation guides the interest of researchers and car manufacturers towards the development of technologies that support an efficient driving style.
This thesis presents the development of a traffic light assistance system with the focus on human factors. The system aims on supporting drivers in approaching traffic light intersections efficiently. In three driving simulator studies, the content related research covered the investigation of the unassisted driving task, the influence of the system on the driver’s perception of the interaction with other road users and the information strategy of the human machine interface. When the traffic light phase changes or when visibility is limited, drivers prepare driving behaviour that is not appropriate for the traffic light phase at arrival at the intersection. These situations offer the greatest potential for the assistance system. The traffic light assistant is able to change driving behaviour. However, the expectation of other road user’s emotional reactions influences driver compliance. In situations in which drivers expected to bother others with their driving behaviour, compliance to the traffic light assistant was low. Further, the deviations of driver behaviour from the target strategy of the traffic light assistant are lowest when the HMI includes the two information units target speed and action recommendations. Traffic light phase information in the HMI is a subjectively important information for drivers. The results point towards the presentation of all three information units.
The method related research covered the development of a method for measuring drivers’ information demand for dynamic stimuli. While driving, specific stimuli are action relevant for drivers, i.e. they need to be processed in order to decide on the appropriate driving behaviour. Eye tracking has been the standard method for measuring information demand while driving. The novel MARS (Masking Action Relevant Stimuli) method measures information demand by masking the dynamic action relevant stimulus in the driving environment or in the vehicle. To unmask the stimulus for a fixed interval, drivers press a button at the steering wheel. In the present thesis, two driving simulator studies evaluated the MARS method. They included measuring information demand for the traffic light phasing and the in-vehicle display of the traffic light assistant. The analyses demonstrate that variations in the experimental conditions influence the information demand measured with the MARS method qualitatively similar to the influences on fixations measured by eye tracking. Due to its simple application, the MARS method represents a promising tool for transportation research.