## Lab 2 Hick's law

Statement of the Problem

The purpose  of this lab experiment is to examine how movement  preparation is in  uenced by the number  of response choices.

Reference

Chapter 2

Materials Needed

•   Two 30 cm rulers

•   Individual  Data Sheet

•   Group  Data Sheet

Procedure

The objective is to catch the ruler or rulers as quickly as possible once released. Note: In this case we will measure “time” by recording cm, acknowledging that the more quickly  a ruler is caught (the lower the time), the less the ruler will drop (the lower the cm measure).

Condition 1: Simple Reaction Time

Divide into pairs. The experimenter will hold one ruler vertically in the hand of his or her choosing at its highest point so that the 30 cm line is closer to the holding point (see Figure 1). The participant will place the thumb  and fore  nger of one hand on either side of the ruler at its bottom (0 cm) without actually touching  the ruler. The experimenter, without giving any indication to the participant, will then release the ruler and the participant must catch it as quickly as possible. Record the numerical  value of the point of the catch (e.g., 15 cm) on the  Individual  Data Sheet. Each participant will complete 10 trials, at which point the experimenter and participant will switch roles.

Condition 2: Choice Reaction Time

Using both  hands,  the experimenter will hold two rulers vertically at their highest point so that the 30 cm line is closer to the holding point (see Figure 1). The participant will place one thumb  and forefinger on either side of each ruler at its bottom (0 cm). The experimenter, without giving any indication to the participant, will then release one of the two rulers and the participant must catch it as quickly as possible. Participants should  strive to avoid performing the catching movement with both  hands.  Record the numerical  value of the point of each catch on the Individual  Data Sheet. Each participant will complete 10 trials, at which point the experimenter and participant will switch roles.

Results

1.  Calculate  total  “time” (in this case represented by cm) by adding up the cm totals  for trials 1 through 10. Record the result on the  Individual  Data Sheet.

2.  Calculate  the mean “time” for each participant by dividing the total by the number  of trials (10).

3.  Obtain the mean Simple RT and Choice RT from the other participants. Place each participant’s data into the group data sheet.

4.  Calculate  the group mean for each task.

5.  Create a bar graph at  www.onlinecharttool.com/graph?selected_graph=bar to represent  the group means for each task.

Discussion

1.  Based on your data,  how was movement  preparation in  influenced by the number  of response choices?

2.  Does Condition 1 accurately  measure reaction  time? Explain.

3.  Why is it important to not let your partner know when you are going to drop  the ruler? Explain.