The Meaning of ＂Existence＂ and the Contingency of Sense

In this paper I argue first for a revisionary ontology, that is, for an understanding of ＂existence＂ as the property of a field not to be empty. In this context, I distinguish between ＂metaphysics＂ （the theory of totality or of fundamental reality） and ＂ontology＂ （the systematic investigation into the meaning of ＂existence＂）. In the second part, I provide a sketch for a corresponding revisionary theory of the modalities in light of the new ontology proposed.     

Sleep deprivation and hallucinations. A qualitative study of military personnel

Much anecdotal evidence suggests that sleep deprivation not only impairs performance, but also brings about other extraordinary effects like hallucinations. However, knowledge about how sleep deprivation may trigger hallucinations is limited. To qualitatively describe hallucinatory experiences during sleep deprivation 12 male military officers from the Norwegian Armed Forces who all had experienced at least one sleep loss-induced hallucinatory experience were recruited. Data were collected and analyzed by semi-structured interviews and thematic analysis. This resulted in the identification of three distinct main themes: (1) Modalities, (2) circumstances/triggers and (3) reactions to hallucinations. Hallucinations were experienced in several modalities (visual, auditory and multi-modality), although visual hallucinations seemed to dominate. Typical reported circumstances/triggers were sleep loss, physical exhaustion, time-of-day, low calorie intake, mental exhaustion and lack of external stimuli (low sensory and social input, boring situations, and monotonous activity). Negative emotions were dominant during the hallucinatory episodes. Often some reasoning and checking on behalf of the officers were necessary to differentiate between real percepts and hallucinations. In some cases the hallucinations caused erroneous actions. Retrospectively, most officers viewed their hallucinatory experiences in light of positive emotions and several emphasized having learned something from them. The results are discussed in relation to the existing literature and suggestions for future studies are outlined.     

Are there attentional demands associated with haptic modalities while walking in young,healthy adults?

Study designA prospective, observational study.ObjectivesTo assess the attentional demands of using haptic modalities during walking using a multi-task paradigm in young, healthy adults.SettingBiomechanics of Balance and Movement (BBAM) Lab, University of Saskatchewan.MethodsTwenty-two (12 male) young, healthy adults performed walking trials with and without a verbal reaction time (VRT) task, as well as with and without the use of haptic anchors and light touch on a railing. Walking performance was evaluated using normalized stride velocity and step width, and dynamic stability was evaluated using step width variability and medial-lateral margin of stability (ML MOS) and its variability.ResultsThere were no significant differences in VRT when walking with and without added haptic input and no interactions between the added VRT task and added haptic input. Step width increased and variability of the ML MOS increased during trials with the VRT task compared to trials without the VRT task. The ML MOS decreased when using both haptic tools with a greater decrease when using light touch on the railing compared to when using the haptic anchors. Normalized stride velocity and step width decreased when using light touch on the railing only.ConclusionBoth haptic tools affected stability during walking. Using the railing to add haptic input had a greater effect on walking stability and was the only haptic tool to affect walking performance. Attentional demands should be considered in future research and applications of adding haptic input during walking.