# Towards Detection of Interest Using Physiological Sensors
## 3 Physiological Patterns and Features of Interest
### EEG and ECG Patterns
Thus, the greater the attention required by the task, the less the resources available to probe stimulus. This, in turn, will cause a reduction in P3 amplitude. The authors of the study differentiated between interesting and neutral states using video clips that were interesting or neutral (neither non-interesting nor boring). The use of interesting vs. neutral stimuli is thought to allow investigation of the effects of interest on the brain in a more proper manner than using interesting vs. boring stimuli, because \"boring\" stimuli might be biased. EEG data were recorded using 21 channels covering most brain areas (frontal lobe, central, parietal lobe, and occipital lobe) besides recording EOG data. Since the experiment used probe stimuli, the correct responses were defined and used to obtaining event-related potential (ERP) waveforms. Scalp topographic maps containing P3 data were drawn after pre-processing and computation. Statistical analysis was then performed to confirm the finding that P3 amplitude decreased when the subjects viewed interesting video clips when compared to neutral stimuli. This finding is consistent with that of [PERSON] et al. [69], who reported that P3 is a sensitive indicator of the subject's interest in video clips. The authors found a significant difference between the neutral and control conditions only for the deviant P3a, and not for the P3b. The authors, therefore, claimed the superiority of the deviant P3 over the target P3 for the assessment of the amount of residual processing resources. This may be explained by the fact that the task demand of the target stimulus, which the subjects were required to respond to, was higher than that of the deviant target, which the subjects could neglect. This would have led to the allocation of more processing resources for the target stimuli. Therefore, it is hypothesized that the frontcentral P3a component might be more sensitive to resource availability than the parietal P3b component. Nevertheless, further research is required to investigate and confirm the above hypothesis, which opens a new direction for the investigation of interest. According to the cognitive model discussed by [PERSON] [70], the P3a originates during task processing by stimulus-driven frontal attention mechanisms, while the P3b originates due to temporal-parietal activity associated with attention and seems to be related to subsequent memory processing and storage. In some way, one may thus argue that prior knowledge, which requires memory processing and updating of operations to relate given information to stored information, is not necessary for the triggering of interest. While many psychological studies have reported a weak or no relationship between interest and prior knowledge e.g., [71; 72; 73] other studies have reported significant correlations between interest and knowledge, e.g., [74]. There is debate regarding the manner in which prior knowledge affects interest, although the effects of interest on knowledge are acknowledged. The four-phase model suggested by [PERSON] and [PERSON] [13] describes the first two phases of interest development as composed of focused attention and positive feeling, while the latter two phases consist of knowledge and stored values, along with positive feelings. Research on interest should carefully consider this issue, as low or high levels of knowledge are expected to decrease the level of interest, while a moderate level of knowledge is reported in some studies to generate interest [75; 76] (for a review see [77]). The study conducted by [PERSON] and [PERSON] [33] suggested the utilization of N140 and P300 elicited by a vibratory probe stimulus to assess interest in subjects presented with particular content. In this study, the authors collected EEG and EOG data from 18 subjects while they watched interesting videos, boring videos, and still images.