I. Introduction
Arachnophobia represents a type of anxiety disorder defined by persistent fear of spiders. When confronted with the phobic object individuals experience very strong negative emotional reactions characterized by feelings of nervousness, fear, or panic. At physiological level anxiety disorders cause an increase in breathing rate and cardiovascular activity. These changes are caused by psychological activation due to default stress response. Several studies have shown that changes in normal heart and breathing rhythm are associated with phobias, anxiety, mental stress, or emotional arousal [2],[4],[9]. In terms of physiological measurements, traditional approaches include the use of electrocardiogram (ECG), electromyogram (EMG), and electroencephalogram (EEG) as means for anxiety and mental stress evaluation [10],[11],[12].