Age (years) Total Responses M(SD) Total Correct M(SD) Correct Heads M(SD)
1.0-2.2 20.4(5.5) 12.6(5.6) 9.2(5.2)
2.2-4.0 23.4(5.1) 14.9(5.5) 10.4(4.3)
4.0-5.0 26.9(4.1) 19.8(6.0) 12.5(3.8)
Table 3.3:Mean (M) and standard deviation (SD) for the total number of responses and the correct number of head turns for each age group per block. Data is averaged over the three rewards types and across the three visits.
Age (years) Total Incorrect M(SD) Incorrect Head M(SD) Null M(SD)
1.0-2.2 7.9(2.0) 0.4(0.4) 7.2(1.7)
2.2-4.0 8.4(2.0) 0.8(1.0) 6.9(2.9)
4.0-5.0 7.1(2.9) 0.6(0.7) 5.9(2.4)
Table 3.4:Mean (M) and standard deviation (SD) for the total number of incorrect responses, the total number of incorrect head turns and the number of null responses for each age group per block. Data is averaged over the three reward types and across the three visits.
This section performs a number of statistical tests to compare the different age groups, reward types and task exposure. These statistical tests shall be dis- cussed at the start of each section where applicable. The statistical tests used in this section are Kruskal Wallis tests. The test is used to see if the data being compared is from the same distribution i.e. are the age groups the same. If differences are seen between the groups, a Mann-Whitney U-test is performed in what is known as, post hoc analysis. The Mann-Whitney U-test is used to see if the two sets of data are the same e.g. differences between age group 1.0-2.2 and 2.2-4.0 years. A Bonferroni correction is used to remove the effect of the multiple comparisons of the groups. Table 3.3 shows the mean number of total responses, the mean number of total correct responses and the mean number of correct head turn responses averaged for all three age groups and averaged over all reward types and visits. As expected, the data shows an in- crease in all the responses as the children get older. For the total number of responses, this increase is significant between the age groups (Kruskal-Wallis test, H(2) =7.3, p <0.05). Post hoc tests show a statistically significant differ- ence only between age groups 1.0-2.2 and 4.0-5.0 years (Mann-Whitney U-test with Bonferroni correction, z=0, p<0.017).
Table 3.4 shows the total number of incorrect responses, number of incorrect head turn responses and the number of null responses. The number of total incorrect responses is highest for the middle age group (2.2-4.0 years) with the least numbers of correct responses being the oldest age group, 4.0-5.0 years, sta- tistically there is no difference, however, between the age groups.
It was expected that the youngest group would have the most incorrect re- sponses out of all of the groups, however, this is not the case. When looking at the null responses however, i.e. ones which are due to inattentiveness of the child and cannot be categorised, the youngest age group (1.0-2.2 years) shows the most. Differences between the age groups are not significant for null re- sponses.
When evaluating localisation ability, we require a high number of correct head turns, across all age groups we see an increase, however, statistically there is no difference. The biggest difference between the correct number of head turns and the total number of responses is for age group 4.0-5.0 years, with correct head turns making up 46.6% of the total number of trials. The smallest differ- ence is for age group 2.2-4.0 years, with head turns making up 44.5% of the total trials. The lowest number of incorrect head turns are for age 1.0-2.2 years (45%), the most incorrect head turns are seen in the age group 2.2-4.0 years, difference of the number incorrect head turns between age groups are not significant.
youngest age group, the mean number of correct and total response was less as compared to the other two groups. The oldest group, 4.0-5.0 years, showed the most responses in terms of both correct and total response, they also showed the lowest number of null responses. This was expected, with the younger chil- dren not willing to sit for as long as the older children.
Other BA studies use innumerable different stimulus and testing conditions. Such studies have the number of trials ranging from approximately 10 to 30 trials for children aged between one and two years [87, 88,89, 90,91]. Studies using VRA to evaluate localisation ability do not comment on the number of trials obtained. If the total number of responses is taken as the measure, then the AnimalSeek method is comparable to other studies. This suggests the child is interested in the task and is willing to sit and engage in it, but the amount of correct head turns is only around 50% of the total number of trials. This could be due to the motion tracking gear the child wears causing them to be distracted or the fact the children were not conditioned to the auditory stimulus in an at- tempt to obtain natural head turn responses.
Total correct responses made up 61.6% of all of the responses made by age group 1.0-2.2 years, 63.8% were correct responses made by 2.2-4.0 years and 73.7% of the responses were correct for the age group 4.0-5.0 years.
The next section will look at the number of responses with respect to the differ- ent visits and also the blocks within those visits. Such analysis will show how well the AnimalSeek method is at engaging and motivating the children.