RESUMO
Face and body perception is mediated by configural mechanisms, which allow the perception of these stimuli as a whole, rather than the sum of individual parts. Indirect measures of configural processing in visual cognition are the face and body inversion effects (FIE and BIE), which refer to the drop in performance when these stimuli are perceived upside-down. Albeit FIE and BIE have been well characterized at the behavioral level, much still needs to be understood in terms of the neurophysiological correlates of these effects. Thus, in the current study, the brain's electrical activity has been recorded by a 128 channel electroencephalogram (EEG) in 24 healthy participants while perceiving (upright and inverted) faces, bodies and houses. EEG data were analyzed in both the time domain (i.e., event-related potentials-ERPs) and the frequency domain [i.e., induced theta (5-7 Hz) and gamma (28-45 Hz) oscillations]. ERPs amplitude results showed increased N170 amplitude for inverted faces and bodies (compared to the same stimuli presented in canonical position) but not for houses. ERPs latency results showed delayed N170 components for inverted (vs. upright) faces, houses, but not bodies. Spectral analysis of induced oscillations indicated physiological FIE and BIE; that is decreased gamma-band synchronization over right occipito-temporal electrodes for inverted (vs. upright) faces, and increased bilateral frontoparietal theta-band synchronization for inverted (vs. upright) faces. Furthermore, increased left occipito-temporal and right frontal theta-band synchronization for upright (vs. inverted) bodies was found. Our findings, thus, demonstrate clear differences in the neurophysiological correlates of face and body perception. The neurophysiological FIE suggests disruption of feature binding processes (decrease in occipital gamma oscillations for inverted faces), together with enhanced feature-based attention (increase in frontoparietal theta oscillations for inverted faces). In contrast, the BIE may suggest that structural encoding for bodies is mediated by the first stages of configural processing (decrease in occipital theta oscillations for inverted bodies).
RESUMO
BACKGROUND: Smoking is a key contributor to health and social inequalities and homeless smoking prevalence rates are 4 times higher than the general population. Research on homelessness and smoking to date has been concentrated predominantly in the US and Australia. This study aimed to describe smoking and quitting behaviour in homeless adult smokers in Great Britain. Data on perceptions of, and willingness to try, e-cigarettes were also gathered. METHODS: Cross sectional survey of 283 adult smokers accessing homeless support services in Kent, the Midlands, London and Edinburgh. Participants answered a four-part survey: i) demographics; ii) current smoking behaviour and dependence (including the Fagerström Test of Cigarette Dependence [FTCD]); iii) previous quit attempts; and iv) e-cigarettes perceptions. RESULTS: High levels of cigarette dependence were observed (FTCD: Mâ¯=â¯7.78, sd⯱â¯0.98). Although desire to quit was high, most had made fewer than 5 quit attempts and 90% of these lasted less than 24â¯h. 91.5% reported that others around them also smoked. Previous quit methods used included cold turkey (29.7%), NRT (24.7%), varenicline (22.3%) and bupropion (14.5%). 34% were willing or able to spend £20 or more for an e-cigarette and 82% had tried one in the past although 54% reported that they preferred smoking. CONCLUSION: We observed high nicotine dependence, few long-term quit attempts, strong desire to quit and amenability to both traditional cessation methods and e-cigarettes. Community embedded and non-routine approaches to cessation may be promising avenues promoting engagement with the homeless community. Likely barriers to uptake include low affordability, preference for cigarettes and high numbers of smoking acquaintances.
