Infants, even newborns, prefer to look at attractive faces compared to less attractive faces (Slater et al., 1998). In this study, infants from 1 to 6 days old were shown two photographs of womens faces. Previously, a group of adults had rated one of the faces as significantly more attractive than the other. The babies were positioned in front of a screen on which the photographs were presented. The pair of faces remained on the screen until the baby accumulated a total of 20 seconds of looking at one of the other. The number of seconds looking at the attractive face was recorded for each infant.

Number of Seconds Spent Looking at Attractive Face

8

10

12

12

13

13

15

17

17

Q2) Use the dataset above to calculate each of the following statistics for number of seconds spent looking at attractive face:

• Mean of the sample (1 point)
• Estimated standard deviation of the population
  • Correct equation used (1 point)
  • Correct value computed (1 point)
• Standard error of the sampling distribution
  • Correct equation used (1 point)
  • Correct value computed (1 point)

Q3) Use the statistics calculated in Q2 to determine whether babies look significantly longer at attractive faces. If the babies had no preference (as stated by the null hypothesis) they would look at each face for 10 seconds (. Use a two-tailed test with . (Total 17 points)

• State your hypotheses using both words and statistical notation
  • Null hypothesis in written and statistical notation form (2 points)
  • Alternative hypothesis in written and statistical notation form (2 points)
  • Calculate standard error (Note: This was calculated in Q2)
  • Correct equation (1 point)
  • Correct value (1 point)
  • Determine the critical value (1 point)
  • Conduct hypothesis test
  • Correct equation (2 points)
  • Correct value (2 points)
  • Comparison of obtained t and critical t in either words or statistical notation form (1 point)
  • Make a decision about rejecting/failing to reject the hypothesis
  • Explicitly states reject or fail to reject (1 point)
  • Writes a 1-2 sentence conclusion interpreting the results, including explicit reference to the independent and dependent variables (2 points)
  • Writes correct conclusion using statistical notation (2 points)