Sight Stimulus Temperature

The effect of the temperature on the reaction time of human hand responding to a sight stimulus

Design

Research Question:
How does the temperature affect the reaction time of human hand in responding to a sight stimulus?

Hypothesis:
Temperature is an important factor in regulating blood supply and nerve signals. Lower temperatures decrease the nerve signals from brain to hand, thereby slow the reaction (Ascroft). When the hand is submerged in cold water, the sensory receptor nerves in the skin recognize the fall in temperature and send signals to the hypothalamus. Then the hypothalamus sends signals that cause blood vessels to constrict in order to preserve heat. Due to the conservation of heat, the lower blood supply slows down the works

Although, the rate of decrease varies, all 6 participants showed a trend of a decrease in the reaction time as water temperature increased. To be specific, for participant 3, the average reaction time decreased from 0.523 seconds to 0.341 seconds as the temperature increased from 7°C to 37°C. Furthermore, according to Figure 2, the total average reaction time of the 6 participants’ records decreased as the water temperature decreased. The equation of the line of best fit y = -0.0026x + 0.4041 further supports the hypothesis by showing that there is a negative correlation between the reaction time of responding to sight stimulus and temperature, since the slope has a negative value. There is not a major outlier since all of the data plots touch the line of best fit. Although, the decrease in the reaction time in Figure 2 has a fairly linear slope, the amount of decrease between each water temperature differs. For example, the fall of the average reaction time between 17°C and 27°C was 0.013 seconds, while the fall of the average reaction time between 27°C and 37°C was 0.047 seconds. Thus, a relatively less sharper decrease in the average reaction time was observed between temperatures 17°C and 27°C than the decrease between temperatures 27°C and 37°C. A lower rate of decrease in the

The volume of the water was not taken into account due to the priority of adjusting the temperature of the water. The lack of consistency in the amount of water may have affected the reaction time, since more coverage of the hand with water will facilitate the process of warming the hand. When there is a larger amount of water in the plastic tub, more surface area of the hand will be submerged by the water. In addition, the hand will be more influenced by the temperature of the water when more surface area of the hand is in contact with the water. One solution is to keep the volume of the water consistent. For example, if the water volume is decided to stay constant as 1000mL for every trial, one can always first fill the tub with 400mL of tap water and then add ice or hot water to manipulate the temperature. In addition, the process can be facilitated by marking 1000mL on the plastic tub since the same tub will be used throughout the