**Cheang Yin Yan**

**Introduction**

**Q1.****What is mental rotation?**

ANS: This is the ability of people to have mental representation and manipulation of three-dimensional physical object, on two-dimensional plane. Shepard and Metzler (1971) demonstrate that people can mentally represent two physical objects on two-dimensional plane as three-dimensional and rotate analogously either one object to match the orientation of the other.

**Q2. ****What did Shepard and Metzler (1971) do in their study? What did they find about the mental rotation of three-dimensional objects?**

ANS: They rotated two-dimensional stimuli of same and different types either in (1) picture plane or in (2) depth in different rotation angles. They measured the reaction time for the participants to determine whether the two stimuli are of same shape. They found a linearly increasing function between rotation angles and reaction time and suggested mental rotation to be an analogous/serial process.

**Q3. ****What did Richardson (1994) do in Experiment 2 of his study? What did he find about gender differences in mental rotation ability?**

ANS: Richardson (1994) conducted Shepard and Metzler (1971)’s mental rotation task and measured the accuracy in order to study the possibility of changes over time for both sexes in mental rotation performance. He found diminished gender effect in mental rotation ability (i.e. men have greater accuracy than women) as compared to Philips and Rawles (1979).

**Q4. ****According to Shepard and Metzler (1971), what would be your hypothesis about the relationship between rotation angle and reaction time (hypothesis #1)? According to Richardson (1994), what would be your hypothesis about the effect of gender on the relationship between rotation angle and reaction time (hypothesis #2)?**

ANS: Hypothesis #1: Reaction time increases linearly with the rotation angle.

Hypothesis #2: There is a gender effect on the relationship between rotation angle and reaction time. Men have shorter average reaction time and shorter reaction time across angular difference than women although both show linear function between rotation angle and reaction time.

**Method**

*Participants*

**Q5. ****How many participants were run in the current experiment? How were they recruited? What was the gender distribution? What were descriptive statistics on age?**

ANS: 72 participants were recruited directly from the PSYC 2007/007 Cognitive Psychology class. The participants were reimbursed with participation marks for class PSYC 2007/0007. Participants were 23 men and 49 women aged 18 to 43 years. The average age of participants was 22.6 years (*SD* = 5.11).

*Apparatus and materials*

*For the details of the experiment:*

http://opl.apa.org/Experiments/About/AboutMentalRotation.aspx

**Q6****. ****What were the visual stimuli used? What equipment and software were used to present the stimuli and collect the response?**

ANS: Two types of stimuli were used (i.e. one is the mirror image of the other). The stimuli on the left was always in same orientation while the stimuli in the right were presented randomly in eight different rotation angles orientations (0, 45, 90, 135, 180, 225, 270, 315 degrees) and of either type (same or different). The stimuli were only rotated in picture plane only.

*Procedure*

**Q7. ****What was (were) manipulated (i.e., what was (were) the independent variable(s))? What was (were) measured (i.e., what was (were) the dependent variable(s))?**

ANS: The independent variables were the rotation angles in degrees, types of trials (same trial has same types of stimuli while different trials have different types of stimuli) and gender of participants. The dependent variables were reaction time in seconds and slope.

**Q8. ****What did the participant need to do in each trial? How many trials were there in each condition? How many trials were there in total?**

ANS: The participant observed and determined whether those two stimuli were the same. The participant was told to prioritize accuracy instead of speed in order to increase the reliability and validity of the results. There were three “different” and three “same” trials for each rotation angle. In total, there were 48 trials.

**Results**

**Q9. ****How did you analyze the data?**

ANS: First, to study the relationship between rotation angles and reaction time, mean slope is analyzed to see if it is different from zero. Next, the average slope and time taken for correct response for both sexes were compared in order to investigate the gender effect on the relationship between rotation angles and reaction time.

**Q10. ****What were the results (both descriptive statistics and inferential statistics) regarding your hypothesis #1 (Q4)?**

ANS: One-sample t-test indicated that the mean slope was significantly larger than 0 (*M*= .0213, *SD*= .0318), *t* (71) = 5.67, *p* < .001, there was a significant linear relationship between rotation angles and reaction time.

**Q11. ****What were the results (both descriptive statistics and inferential statistics) regarding your hypothesis #2 (Q4)? Please include a figure showing the results regarding this hypothesis.**

ANS: An independent-sample t-test indicated the mean reaction time was significantly shorter for men (*M*=3.16, *SD*=.928) than for women (*M*=4.58, *SD*=3.00), *t* (70) = 2.21, *p*=.030 *d*=.639. An independent-sample t-test also indicated that women (*M*=.0265, *SD*=.0366) had significant greater mean slope than men (*M*=.0102, *SD*=.0123), *t* (70) =2.07, *p*=.042, *d*=.595.

**Discussion**

**Q12. ****What is your interpretation of the results reported in Q10 and Q11?**

ANS: There was a significant positive linear relationship between rotation angles and reaction time for both men and women as the mean slope was positive and significantly different from 0. Also, there was a gender effect on this linear relationship, where men were found to have shorter mean reaction time and smaller average slope than women. Hence, the results indicated that men had stronger mental rotation ability than women.

**Q13. ****Given the results, how will you conclude regarding your hypothesis #1 and hypothesis #2?**

ANS: Both hypothesis #1 and #2 were accepted. Reaction time increases linearly with the rotation. There is a gender effect on the relationship between rotation angle and reaction time. Men have shorter average reaction time and shorter reaction time across angular difference than women although both show linear function between rotation angle and reaction time.

**Q14. ****How do you compare your findings with Shepard and Metzler (1971) and Richardson (1994)?**

ANS: The findings were consistent with Shepard and Metzler (1971)’s. However, since Richardson (1994) measured accuracy whereas this study measured the reaction time to study the gender effect, the findings cannot be compared with the expectation and did not match the hypothesis of Richardson (1994) that the gender difference is being diminished. Nonetheless, since accuracy is always correlated with reaction time, the findings supported Richardson (1994)’s findings that men have higher mental rotation ability than women.

**Q15. ****What is one possible direction for future research on this topic?**

ANS: Based on Cherney (2008)’s research regarding impacts of computer game experience on women’s mental rotation performance, one possible direction for future research on mental rotation topic will be the study of brain regions activated while playing computer games and performing mental rotation tasks to examine the role of such brain regions in mental representation.