Table 6.

Characteristics of Studies Integrated relating to RQ2.

No.	Authors	Study Design	Study Population	Intervention	Comparison	Outcome
1	Sakamoto et al., 2009	cross-over trial (quasi-RCT)	11 healthy subjects aged 24–42 years (mean age: 30.9 years; 8 males, 3 females) for Experiment 1. 9 healthy subjects aged 25–43 years (mean age: 30.6 years; 8 males, 1 female) for Experiment 2.	gum chewing	no gum chewing	reaction time
2	Smith 2010	cross-over trial (quasi-RCT)	133 adults aged 19–39 years (mean age: 22.6 ± 4.4 years; 64 males, 69 females)	gum chewing	no gum chewing	reaction time
3	Tucha & Simpson, 2011	Randomized cross-over trial (quasi-RCT)	42 healthy young adults (mean age 22.2 ± 2.4 years; 21 males, 21 females)	gum chewing	no gum chewing	reaction time

RQ: Research question.