Coding and reliability of items
Experiences with and knowledge of robots were reverse-coded with higher scores indicating a higher degree of experience and knowledge. The degree of acceptance of robots was also reverse-coded with a higher score indicating higher acceptance.
For each type of robot, Cronbach’s reliability coefficient α for the four items related to the degree of acceptance was calculated to confirm the internal consistency. These coefficients were α = 0.921, 0.918, and 0.921 for vacuum, pet-type, and communication robots, respectively. Since these values showed sufficient internal consistency, the degree of acceptance of each type of robot was calculated as the sum of the corresponding item scores (min: 4, max: 20).
Experiences with robots
A χ2-test with gender × experiences (2 × 3 cross table) was conducted for each type of robot. As a result, there was no statistically significant gender bias on experiences with any of the three robot types (χ2(2) = 0.238, p = 0.888, V = 0.028 for vacuum robots; χ2(2) = 1.142, p = 0.565, V = 0.062 for pet-type robots; χ2(2) = 1.853, p = 0.396, V = 0.079 for communication robots).
One-way analysis of variance (ANOVA) consisting of experiences with robots as the independent variable and age as the dependent variable was conducted for each type of robot to investigate the relationships between experience and age. There was no statistically significant difference in vacuum robots (F = 2.903, p = 0.052, η2 = 0.020). On the other hand, statistically significant differences were found for pet-type and communication robots (F = 4.155, p = 0.017, η2 = 0.027 for pet-type robots; F = 7.142, p = 0.001, η2 = 0.046 for communication robots). Post-hoc analyses with the Bonferroni method showed that for pet-type robots, the mean age of participants who had seen these robots only via media (M = 46.8) was higher than the mean age of those who had actually seen these robots (M = 41.7) at a statistically significant level of 5%. Similarly, it was shown that for communication robots, the mean age of participants who had seen these robots only via media (M = 48.0) was higher than the mean age of those who had actually seen these robots (M = 47.7) and the mean age of those who had never seen these robots (M = 40.8) at statistically significant levels of 1%.
Moreover, the Friedman test was conducted to compare experience with the three robot types. The results showed a statistically significant difference between the robot types (χ2 = 21.692, p < 0.001). Figure 1 shows the distributions of experiences with each of the three types the robots. Post-hoc analysis based on Wilcoxon tests with Bonferroni correction revealed the tendency that the rate of participants who had actually seen vacuum robots was higher than the rates of those who had actually seen the other types of robots (p < 0.001, r = 0.260 between vacuum and pet-type robots; p < 0.01, r = 0.200 between vacuum and communication robots).
Knowledge of functions of robots
A χ2 test with gender × knowledge (2 × 4 cross table) was conducted for each type of robot. As a result, there was no statistically significant gender bias on knowledge with any the three robot types (χ2(3) = 0.615, p = 0.893, V = 0.045 for vacuum robots; χ2(3) = 4.922, p = 0.178, V = 0.128 for pet-type robots; χ2(3) = 5.025, p = 0.170, V = 0.129 for communication robots).
One-way ANOVA consisting of knowledge as the independent variable and age as the dependent variable was conducted for each type of robot to investigate relationships between knowledge and age. There was no statistically significant difference in any of the three types of robots (F = 2.035, p = 0.109, η2 = 0.020 for vacuum robots; F = 1.968, p = 0.119, η2 = 0.020 for pet-type robots; F = 2.459, p = 0.052, η2 = 0.024 for communication robots).
Moreover, the Friedman test was conducted to compare knowledge between the robot types. The results showed a statistically significant difference between the robot types (χ2 = 14.725, p < 0.001). Figure 2 shows the distributions of knowledge of functions of the robots. Post-hoc analysis based on Wilcoxon tests with Bonferroni correction revealed the tendency that the rates of participants who knew about the functions of vacuum robots well or a little were higher than the rates of those who knew about the functions of the other types of robots (p < 0.001, r = 0.230 between vacuum and pet-type robots; p < 0.05, r = 0.150 between vacuum and communication robots).
Social acceptance of robots
Three-way mixed ANOVA with gender (male, female) × generation (five age groups from 20 to 60 s) × robot types (vacuum, pet-type, communication; within-participant factor) was conducted for the acceptance score of the robots to investigate relationships between gender, age, and types of robots. Table 4 shows the results. Only the main effect of robot types was statistically significant.
Table 4 Results of three-way mixed ANOVA for acceptance score of robots Post-hoc analysis based on paired t tests with Bonferroni correction revealed statistically significant differences between vacuum and pet-type robots (t = 6.575, p < 0.001, r = 0.360), between vacuum and communication robots (t = 4.372, p < 0.001, r = 0.250), and pet-type and communication robots (t = − 3.286, p < 0.01, r = 0.190). Figure 3 shows the means and standard deviations of the acceptance scores of the robots.
Influence of experience and knowledge on social acceptance of robots
Linear regression analyses with experiences with and knowledge of functions of robots as independent variables and acceptance scores of robots as the dependent variable were conducted for each type of robots to investigate the relationships between social acceptance of the robots, and experience and knowledge. Table 5 shows the results.
Table 5 Results of linear regression analyses for acceptance scores of robots It was found that in vacuum robots experience and knowledge positively affected the acceptance of the robots, although only the knowledge affected on pet-type and communication robots.