Introduction

Paul Fitts’ was the first to discover the relationship between the speed of movement and accuracy requirements. This has become one of the most fundamental principles of motor control. Fitts claims a relationship between task difficulty and movement time. He quantified task difficulty as “index of difficulty” which consists of the ratio of twice the amplitude over width of the target (2Amplitude/Width). This relationship states that when movement amplitude decreases or when target width increases movement time is shorter (Fitts, 1954). Fitts found that the relationship between amplitude and width was given by the equation: MT= a + b[log2(2A/W)]. The empirical constants a and b represent the y-intercept and the slope (Schmidt & Lee, 2011). The purpose of this laboratory was to investigate the linear relationship between the index of difficulty and movement time. Furthermore, the target width-amplitude relationship was observed. The goal was to determine the effect of task difficulty on movement time. Based on Fitts’ law, it was hypothesized that the relationship between movement time and index of difficulty would increase linearly.

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Refer to lab protocol for exact measurements. For each trial, the participant had to move a stylus between two targets, moving as fast as possible while maintaining accuracy. Each trial consisted of a fifteen second period, the number of total taps was recorded. Results from five participants were taken. Results represented movement times for index’s of difficulties of 1-4. The index of difficulty was an independent variable, movement time the dependent variable. It was expected that movement time was to increase with an increase in index of