The Stroop Effect

The belief that thought, and therefore nervous impulses, occurred instantaneously, became a setback in relation to the advances in the theory of psychological processes. Johannes P. Mueller (1801-1858), a German physiologist, estimated the speed of the nerve impulse was eleven miles per second. This claim discouraged scientific research and encouraged a more mystical interpretation of the mind due to the immeasurably fast rate the nerve impulse travels. An experiment carried out by Herman Ludwig Ferdinand von Helmholtz (1850), found the speed of the nerve impulse much slower than Mueller estimated (between 50 and 100 meters per second).

The purpose for the present day study was to measure the speed of the nerve impulse in a student population in order to replicate the findings of Helmholtz (1850). Therefore, it is hypothesized that the speed of the nerve impulse will be between 50 and 100 meters per second.

Method

Participants.

The 22 participants in this study were undergraduate university students enrolled in an introductory psychology course. They participated as part of a laboratory program for this course. 82% were female.

Materials.

The materials used for this experiment included a group of 6 participants (5 people and 1 time keeper), a stopwatch, tape measure and record sheet. To begin with, the timekeeper measured and recorded the distance from the ankle to the brain, and the upper arm to the brain of the third tallest in the group. The next step was to get the 5 participants to sit in a circle on the floor, both feet in the centre, and eyes closed. Each participant was instructed to place one hand around their neighbour’s ankle to begin the trial. The trial requires each participant to squeeze their neighbour’s ankle 5 times. The participant must only squeeze their neighbour’s ankle once their own has been squeezed. The same procedure is conducted by using the upper arm. The time keeper conducted and recorded 5 counterbalanced trials (trial 1-ankle, trial 2-upper arm, trial 3-upper arm, trial 4-ankle) for this experiment. For each trial, we divided the number of subjects per group (i.e.5) by the number of trials (5) therefore, we divide by 25. This gives us the average individual time. The average