Experimental Design

16 2. Designing an Experiment

other words, there is an error in locating the target. There is also physiological

noise—such as the random background firing of neurons or when a neuron is

repeatedly presented with the same stimulus (Bradley et al., 1987; Newsome

et al., 1989).

When looked at another way, this inaccuracy of the human system actually

represents a critical but often forgotten aspect of humans: we cannot produce

exactly the same action twice, no matter how hard we try. For example, take a

pen and a blank piece of paper. Swing the pen towards the paper quickly and

make a mark on it with the pen. Now, try to hit precisely the same spot again, ...