Xanarelle et al., - Oddball

19.04.2016
Ableton Live 9.2.3 + pd-extended 0.43.4 (https://puredata.info/) This work was made from the data I recorded during my Master’s experiment. The experiment aims to study the way our brain is using affective information to guide visual search on the human face (https://en.wikipedia.org/wiki/Visual_search#Face_recognition_in_visual_search). By listening to this track you are taking part to the experiment, going through three blocs of stimuli arranged in "oddball" fashion (https://en.wikipedia.org/wiki/Oddball_paradigm). The regularly-spaced blips that you can hear are in fact electroencephalographical event-related potentials (ERP ; https://en.wikipedia.org/wiki/Event-related_potential) recorded at electrode Pz, which is located just above primary visual areas. ERP were converted to frequency modulations using a homemade PureData script, and the obtained sound samples, differing for each stimulus condition, were played using Ableton Live 9. Basically, what is salient to the listener is the difference between the frequently-repeated stimulus and the rare stimuli. These differences are thus the result of discrepancies in the cortical processing of various emotional facial expressions. LOW SPATIAL FREQUENCIES (STIMULI) 24 grey pictures of eight individuals All neutral faces were less intense Images were trimmed manually Placed at the center of a grey Invisible markers adjust the position of the eyes Filtered to retain only spatial frequencies between Distance and luminance Contrast was normalized Across all the created images, using the SHINE MEDIUM SPATIAL FREQUENCIES (TASK) The participant sat in a dim light room Detect the occurrence of an interval randomly varying The neutral face of a certain model HIGH SPATIAL FREQUENCIES (RECORDING SYSTEM) The impedance of all electrodes was maintained under reference Then used to suppress An automatic artifact Epochs were created Baseline was corrected from the epoch’s beginning Epochs were averaged between Latencies FIVE MINUTE BREAK TO RELAX Many thanks to Team Franco for collaborating on this project : Antonin Tran (Moral support through composition) Antoine Bellemare-Pépin (Textual patchwork) Emma Campbell (Voices) Benjamin Hébert-Seropian (Remix/mastering)

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