Question

In an​ experiment, 18 babies were asked to watch a climber attempt to ascend a hill. On two​ occasions, the baby witnesses the climber fail to make the climb.​ Then, the baby witnesses either a helper toy push the climber up the​ hill, or a hinderer toy preventing the climber from making the ascent. The toys were shown to each baby in a random fashion. A second part of this experiment showed the climber approach the helper​ toy, which is not a surprising​ action, and then the climber approached the hinderer​ toy, which is a surprising action. The amount of time the baby watched the event was recorded. The mean difference in time spent watching the climber approach the hinderer toy versus watching the climber approach the helper toy was 1.05 seconds with a standard deviation of 1.85 seconds. Complete parts a through c.

​(a) State the null and alternative hypotheses to determine if babies tend to look at the hinderer toy longer than the helper toy. Let mu Subscript dequalsmuhindererminusmuhelper​, where muhinderer is the population mean time babies spend watching the climber approach the hinderer toy and muhelper is the population mean time babies spend watching the climber approach the helper toy.
​(b) Assuming the differences are normally distributed with no​ outliers, test if the difference in the amount of time the baby will watch the hinderer toy versus the helper toy is greater than 0 at the 0.05 level of significance.

State the conclusion for this hypothesis test.

​(c) What do you think the results of this experiment imply about​ babies' ability to assess surprising​ behavior?

Answer 1

a) The hypothesis are:

H0: The babies tend to look at the hinderer toy equal to or less than the helper toy.

H1: The babies tend to look at the hinderer toy longer than the helper toy.

b) Assuming that the differences are normally distributed we can test the above hypothesis using the paired t test. The test statistic under the null hypothesis is:

t = ¯d/ SE( ¯d) . where SE( ¯d) = sd/√ n

t = 1.05/(1.85/sqrt(18)) = 2.408

The corresponding p-value is 0.0138.

Since, the p-value is less than 0.05 we reject the null hypothesis at 5% leve of significance and conclude that the babies tend to look at the hinderer toy longer than the helper toy.

c) From the results of the test conducted one could conclude at 5% level of significance that the babies tend to observe the surprising action more than the normal behavior which in return shows that the babies exhibit the ability to assess surprising behavior.