TABLE 4.

Results of the descriptive statistics of cognitive engagement.

Data sources	Dimension of measurement	Question feedback	Sample size	Average value	Standard deviation
Questionnaire	Cognitive engagement	No feedback	30	18.70	3.39
		Simple feedback	30	19.17	2.90
		Elaborated feedback	31	20.45	2.81
Brain wave instrument	Concentration	No feedback	30	44.88	3.69
		Simple feedback	30	48.45	3.76
		Elaborated feedback	31	47.33	4.97
Eye movement meter	Total gaze duration	No feedback	30	58.94	9.62
		Simple feedback	30	68.07	11.98
		Elaborated feedback	31	72.48	8.67
	Total number of looks	No feedback	30	256.27	36.80
		Simple feedback	30	306.70	48.52
		Elaborated feedback	31	311.13	45.74