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- 2019 (2) (entfernen)
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- Englisch (2) (entfernen)
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- Institut für Experimentelle Wirtschaftspsychologie (Lünelab) (2) (entfernen)
Decoding the psychological dimensions of human odor perception has long been a central issue of olfactory research. As odor percepts could not be linked to a few measurable physicochemical features of odorous compounds or physiological characteristics of the olfactory system, odor qualities have often been assessed by perception–based ratings. Although these approaches have been promising, none of the proposed system has sustained empirical validation. In a review of 28 studies, the authors assessed how basic characteristics of study design have been biasing perception–based classification systems: (1) interindividual differences in perceptual and verbal abilities of subjects, (2) stimuli characteristics, (3) approaches of data collection, and (4) methods of data analysis. Remarkably, many of the difficulties in establishing these systems have been rooted in one underlying issue: the puzzling relationship between language and olfaction in general. While the reference from odors to language is weak, the reverse impact of verbal processing on olfaction seems powerful. Odor perception is biased by verbal–semantic processes when cues of an odor's source are readily available from the context. At the same time, olfaction has been characterized as basically sensation driven when this information is absent. The authors examined whether language effects occur when verbal cues are absent and how expectations about an odor's identity shape odor evaluations. Subjects were asked to rate 20 unlabeled odor samples on perceptual dimensions as well as quality attributes and to eventually provide an odor source name. In a subsequent session, they performed the same rating tasks on a set of written odor labels that was compiled individually for each participant. It included both the 20 correct odor names (true labels) and – in any case of incorrect odor naming in the first session – the self–generated labels (identified labels). The authors compared odor ratings to ratings of both types of labels and found higher consistencies between the evaluation of an odor and its identified label than between the description of an odor and its true (yet not associated) label. These results indicate that basic perceptual as well as quality ratings are affected by semantic information about an odor's source – even in absence of source cues. That is, odor sensation may activate a semantic mental representation of an odorous object that affects odor processing and may in turn relate to further multimodal properties. That means, associations between odors and stimuli from other sensory modalities should not only be stable, but these mappings should be mediated by an odor’s identity. The authors asked subjects to visualize their odor associations on a drawing tablet, freely deciding on color and shape. Additionally, they provided a verbal label for each sample. Color mappings were odor-specific, they reflected the imagery of a natural source and seemed to change with assumed odor identity. Shape mappings changed with odor identifications as well, as drawings frequently displayed concrete objects that reflected visual features of an odor's source. The influence of verbal identity codes on quality ratings or crossmodal mappings is rooted in the very same problem that perception–based classification systems have tried to solve – a terminology that relates to abstract mental categories. The less specific we communicate, the more we need to resort to source–related analogies – in scientific endeavors and everyday life alike.
When Libet and colleagues published their results on the temporal order of movement preparation and the reported time of conscious will to move in 1983, they shed some doubt on the existence of free will. This marked the beginning of a controversial and still ongoing debate, not only about the existence of free will, but also about the appropriateness of methods and validity of results from research on free will. Belief in free will was also discovered as psychological research topic. Literature on belief in free will shows some evidence that most laypersons across different cultural backgrounds believe that they have free will and that a person's belief in free will might have an impact on cognition and behavior, tending to positive outcomes with a greater belief in free will. Empirical findings from the German-speaking area are sparse, probably due to a lack of validated measurements assessing belief in free will available in the German language. The aim of this dissertation is to critically examine some aspects in psychological research on free will and the belief in free will. Two studies are reported that aim to generalize the Libet paradigm for a free and voluntary decision with consequences for the acting person, as this was never reported to have been researched in literature before, and to test the critical objection that the measurement of reporting the conscious intention to move has a direct effect on the result in the Libet paradigm. Furthermore, the construction of the first inventory measuring belief in free will in the German language is described. This inventory was also created with the aim of overcoming some methodological problems in the existing instruments in English language. Furthermore, studies on the experimental manipulability of the belief in free will are reported. These findings provide implications in view of the current state of research on free will and belief in free will and its reliability.