Alex H. Bullinger

Immersive virtual environments in cue exposure.

Cue reactivity to drug-related stimuli is a frequently observed phenomenon in drug addiction. Cue reactivity refers to a classical conditioned response pattern that occurs when an addicted subject is exposed to drug-related stimuli. This response consists of physiological and cognitive reactions. Craving, a subjective desire to use the drug of choice, is believed to play an important role in the occurrence of relapse in the natural setting. Besides craving, other subjective cue-elicited reactions have been reported, including withdrawal symptoms, drug-agonistic effects, and mood swings. Physiological reactions that have been investigated include skin conductance, heart rate, salivation, and body temperature. Conditioned reactivity to cues is an important factor in addiction to alcohol, nicotine, opiates, and cocaine. Cue exposure treatment (CET) refers to a manualized, repeated exposure to drug-related cues, aimed at the reduction of cue reactivity by extinction. In CET, different stimuli are presented, for example, slides, video tapes, pictures, or paraphernalia in nonrealistic, experimental settings. Most often assessments consist in subjective ratings by craving scales. Our pilot study will show that immersive virtual reality (IVR) is as good or even better in eliciting subjective and physiological craving symptoms as classical devices.

Age-related changes in cognitive conflict processing: An event-related potential study

Cognitive tasks involving conflicting stimuli and responses are associated with an early age-related decline in performance. Conflict and conflict-induced interference can be stimulus- or response-related. In classical stimulus-response compatibility tasks, such as the Stroop task, the event-related potential (ERP) usually reveals a greater negativity on incongruent versus congruent trials which has often been linked with conflict processing. However, it is unclear whether this negativity is related to stimulus- or response-related conflict, thus rendering the meaning of age-related changes inconclusive. In the present study, a modified Stroop task was used to focus on stimulus-related interference processes while excluding response-related interference. Since we intended to study work-relevant effects ERPs and performance were determined in young (about 30 years old) and middle-aged (about 50 years old) healthy subjects (total n=80). In the ERP, a broad negativity developed after incongruent versus congruent stimuli between 350 and 650 ms. An age-related increase of the latency and amplitude of this negativity was observed. These results indicate age-related alterations in the processing of conflicting stimuli already in middle age.

Real-time monitoring of brain activity in patients with specific phobia during exposure therapy, employing a stereoscopic virtual environment.

Exposure therapy is a behavioral technique that is reported to be the most effective, long-lasting treatment for patients suffering from specific phobia. During the performance in enclosed spaces, the patients show a strong psychophysiological response to the phobic stimulus that is normally avoided. This psychophysiological response changes characteristically during the course of exposure. We implemented an electroencephalographic monitoring focusing on event-related potentials to resolve the modulation of preattentive information processing by the anxiety state of the subject. Therefore, mismatch-negativity (MMN) was chosen as parameter using a passive auditory oddball paradigm that does not interfere with performance in the virtual environment. The results of this neurophysiological monitoring are demonstrated in one patient suffering from claustrophobia.

Monitoring Brain Activity During Use of Stereoscopic Virtual Environments

Performance in virtual environments (VEs) is strongly modulated by attention-related factors such as the preattentive state of the brain. Because this state changes over time and might also be infl...

Three-Dimensional Virtual Reality as a Tool in Cognitive-Behavioral Therapy of Claustrophobic Patients

At present we are conducting a control group-controlled multimodal study, using a three-dimensional virtual environment as a therapeutical tool. Monitoring includes measurement of psychopathological, neurobiochemical, and neurophysiological parameters. In particular, this study is aimed to explain, whether 3D VEs can be used to treat claustrophobia on the one hand for stimulus presentation, on the other hand as a therapeutically useful exposure environment. First, a pilot study was conducted in 1997, in which 13 healthy subjects and two claustrophobic patients were examined concerning the question, whether during an uninterrupted exposure time of 45 min, there were significant variations of the measured physiological parameters and related side effects or side effects subjectively impairing the subjects. We concluded from the results of that investigation, that a 45-min expodure, as far as the tested subjects were concerned, cannot be regarded as anxiety- or stress-inducing in itself.

SAFEGUARD seat/compartment evaluation methodology for vehicles with suspended seats

Back pain is observed in a high percentage of professional drivers of heavy-duty vehicles and trucks. It was found that whole-body vibrations, prolonged sitting and posture, because of task handling and seating system, are the main factors in the development of back pain. The attenuation of vibrations and the provision of a good ergonomic posture at all times are therefore becoming more important. To achieve this a better knowledge of human behaviour towards vibrations and when seated on suspended seats is required using more appropriate evaluation techniques. The EC project SAFEGUARD aims at developing a new seat evaluation methodology where with controlled vibration tests and virtual reality simulations as many features as possible of human behaviour when seated on suspended seats are combined. The results of this combined methodology will lead to better understanding of the driver–seat–cabin system and the relation to comfort and health. They will also provide a more accurate way to interpret the efficiency of new seat features in improving comfort and health.

Monitoring Human-Virtual Reality Interaction: A Time Series Analysis Approach

Optimization of Virtual Environments (VEs) in the Mental Health field as well as in other application areas depends heavily on the exact knowledge of the technologys impact on mental work load, st...

Low-loss filter for stereoscopic projection with LCD projectors

To overcome the disadvantage of the low light output of common LCD Projectors when used in combination with polarizing filters, we developed a new combination of half-wave retarder plates and a polarizing filter. The paper points out, that the use of modern LCD Projectors in combination with the newly developed filter results in less light loss than using standard polarizing filters for stereoscopic projections either with LCD or DLP Projectors. We have combined a color selective half-wave retarder plate (CSR) with an achromatic half-wave retarder plate (AR). The CSR with its optical axis oriented 45° to the green light only rotates the spectrum in the 520nm-565nm range by 90°. This means that the red and blue components remain untouched and all the light passing through the first filter will be oriented vertically. The AR then is oriented in that way that all the light after the CSR will be rotated to the desired +/-45° polarization state. We added a third high transmissive polarizing filter with its orientation parallel to the transmitted light in order to cut off any noise which is not perfectly polarized.

A Rapid Prototyping Framework for the Development of Virtual Environments in Mental Health

Virtual Environments (VEs) can be used as a tool for the analysis of mental parameters as well as for therapy of special mental disorders. The framework allows the rapid development of virtual envi...