Диссертации, представленные на защиту и подготовленные в НИУ ВШЭ

Narratives, in the form of, e.g., videos or audio messages, can display the opinion of others and they can provoke a variety of emotions. Such elements can widely shape everyday decision-making, which makes narratives a particularly effective means of social influence. The present dissertation investigated how persuasive narratives can influence decision-making by inducing certain emotions or by conveying the opinion of experts. We studied these effects at the behavioural level, as well as at the neural level using electroencephalography (EEG). We found that narrative-evoked sadness increases risk-aversion, especially in individuals with low levels of emotional contagion. Moreover, we demonstrated that a narrative by an expert against sugar consumption can decrease individuals’ willingness to pay for sugar-containing food. Finally, our EEG data suggested that the persuasiveness of a narrative positively depends on how similarly people’s brains respond to it. Overall, the dissertation expands knowledge on the neurocognitive mechanisms of social influence on decision-making through narratives.

Numerous cognitive studies have demonstrated experience-induced plasticity in the primary sensory cortex, indicating that repeated decisions could modulate sensory processing. In this context, we investigated whether an auditory version of the monetary incentive delay (MID) task could change the neural processing of the incentive cues that code expected monetary outcomes. To study sensory plasticity, we presented the incentive cues as deviants during auditory oddball sessions recorded before and after training during the two MID task sessions, where we focused on the changes in mismatch negativity (MMN) and P3a components. We found that negative outcomes were accompanied by appearance of the feedback-related negativity (FRN), which amplitude was modulated by probability and magnitude of the monetary outcome. In the oddball sessions, we found that MMN and P3a components changed their amplitudes after 2 sessions of the MID task. At the individual level, the training-induced change of mismatch-related negativity was correlated with the amplitude of the feedback-related negativity (FRN) recorded during the MID task. Our results show that the MID task evokes plasticity changes in the auditory system associated with better passive discrimination of incentive cues and with enhanced involuntary attention switching towards these cues.

Systems that process electrophysiological measurements of brain activity in real time, in particular, brain-computer interfaces (BCIs), are used in a number of fields for various research and practical purposes. Most often, such systems use non-invasive recording methods, which are safe and available but introduce limitations in signal quality and throughput that bound the complexity of BCIs that can be implemented with this technology. Invasive recording techniques, on the other hand, give access to more informative signal but pose their own risks and limitations related to the required medical procedures. A currently emerging trend in BCI development is using electrocorticogram (ECoG), an invasive method that is considered to be safer than microelectrode implantation and is routinely used in clinical practice. ECoG yields high spatial resolution, low noise levels, near absence of oculographic and myographic artifacts, proximity to the signal sources and possibility to conduct cortical stimulation through the electrodes, all of which are desirable characteristics for implementation of a complex BCI. In our work, firstly, we propose methods utilizing additional information to improve decoding in non-invasive interfaces, and, secondly, develop experimental paradigms and signal processing methods for ECoG, allowing to perform real-time finger movement decoding, passive cortical mapping, and explore the artificial haptic feedback that could be carried out through ECoG stimulation.

Using electroencephalogram (EEG) and transcranial alternating current stimulation (tACS), our research team sought to identify a neural signature associated with risky decision making. Initially, we aimed at stimulating a network associated with risky decision making by stimulating the left and right frontal hemisphere with various frequencies. We discovered that 20 Hz stimulation applied to the left frontal hemisphere increased participants choice to select risky options. We then aimed to confirm our findings with time-frequency analysis using EEG. In this experiment, not only did we confirm the neural signature of risky decision making, it appears that 20 Hz (or beta rhythm) may account for a learning mechanism between decisions.