During the phobic response, adrenaline secretion produces a wide array of symptoms which enhances the "fight or flight" response. As Garcia-Lopez (2013)[14] has noted, symptoms can include acute hearing, increased heart rate and blood pressure, dilated pupils, increased perspiration and oxygen intake, stiffening of neck/upper back muscles, and dry mouth. Uncontrollable shaking is also common and often occurs prior to the phobia-eliciting stimulus.