Prior research shows that stylistic ad manipulations (i.e., the style or manner in which product visuals are presented in an ad) impact consumer perceptions (Yang, Zhang and Peracchio 2010). This dissertation explores the impact of presence (versus absence) of a product’s shadow in the ad frame, as a visual stylistic manipulation influencing consumer ad perceptions. While many stylistic manipulations have been explored in the past, product shadows in how they impact ad perceptions have not been explored. Drawing on a holistic understanding on object shadows from the visual art, cognition and psychophysics literature streams, this dissertation investigates how product shadows impact ad perceptions. It applies theoretical tenants of Gestalt psychology, Construal Level Theory (CLT), and information paradigms including Signal Detection Theory (SDT) in deriving seven specific hypotheses. It also tests for moderating factors (such as individual consumer aesthetics, gestalt versus component visual processing modes, and product luxury positioning) that may alter consumer ad evaluations and ad effectiveness perceptions based on this stylistic manipulation of product shadow. Findings from this dissertation reveal that the presence (vs. absence) of a product’s shadow in an ad frame enhances the product’s visual form. This visual appraisal of the product in the ad frame further improves the ad’s overall evaluations. The effects of a product shadow on ad attitudes is positively moderated by an individual’s aesthetic tendencies (specifically their response tendencies towards visual aesthetics), a gestalt-focused (vs. component-focused) visual processing mode, as well as a luxury based ad’s positioning. There is also some support for negative effects of product shadows in component-focused ad scenarios, where they act as visual impairments rather than enhancers of the product form and aesthetics. Theoretically, this dissertation extends prior research on stylistic manipulations of product images in visual ad frames, while building upon established ad communication paradigms, including AIDA and Hierarchical Processing Model, HPM (Peracchio and Meyers-Levy 2005; Yang, Zhang and Peracchio 2010). Managerially, findings from this dissertation have implications for print, online, in-store and thus, any form of visual advertising portraying a product form. It outlines specific contexts under which managers can systematically employ (or evade) product shadows to not only enhance ad evaluations, but also to optimize their ad message efficacies. Stylistic image manipulations comprise production elements (e.g., camera angles), and only affect the way in which the product is displayed, i.e., not the core product image itself (Peracchio and Meyers-Levy 2005; Yang, Zhang and Peracchio 2010). Hence, these can be employed as strategic tools towards ad effectiveness (Barry and Howard 1990). Marketers can not only specifically target and position promotions incorporating product shadows towards aesthetically-attuned consumers, but also save advertising costs by omitting them if their presence hinders the communication of the intended message in certain scenarios.

Four studies including ten experiments adresses interrelations between some major and classical issues in visual perception: 3-D perception, colour constancy, colour perception and colour vision deficiencies. The main experimental paradigm to investigate the issues is within that of simulated shape from shading. 3-D impressions are induced by projecting space-modulated illuminations onto flat surfaces (displays), varying the colours and layout of the displays and the colour and modulation of the illumination. Study I includes four experiments investigating three types of space- modulated illumination. All experiments confirmed earlier findings that chromatic colour and complex display layout with reflectance edges crossed by illumination edges enhances shape from shading. In Study II the impressions of shape from shading and real 3-D objects were compared between persons with deutan colour vision deficiencies and normals. As predicted, the deutans show fewer and less distinct 3-D impressions in situations with their specific "problem colours" red and green. They also show a generally lower tendency for 3-D impressions, interpreted as a generally weaker colour constancy. Study III presents the AMBEGUJAS phenomenon; a novel twofold ambiguous shape from shading situation, continuously alternating between two different 3-D impressions coupled with different colour attributions. One solution is of an object with two clear surface colours, the other one of an object with greyish (desaturated) colours in coloured illumination which means classical colour constancy. The phenomenon illustrates the visual processes of separating reflectance and illumination characteristics and may provide a useful experimental setting to study colour constancy. In Study IV the AMBEGUJAS phenomenon is found to be robust as to chromaticness and different luminance contrasts for both normals and deutans. However, the deutans show slower shifts between percepts and a less pronounced desaturation of colour, which indicates a weaker colour constancy. The studies add evidence to the contribution of colour to 3-D shape perception, validated in a novel way by the results on "colour-blinds". The AMBEGUJAS phenomenon provides further support that the factors affecting shape from shading and the deutans different impressions are to be understood with reference to colour constancy. The deutans different impressions compared to normals are remarkable per se, but probably with very limited implications to everyday life. / <p>Diss. (sammanfattning) Umeå : Umeå university, 1996, härtill 4 uppsatser</p> / digitalisering@umu