## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Evaluation Type** & \multicolumn{8}{c}{**Semantic Pair**} \\ \hline  & & \multicolumn{3}{c}{Slippery-Sticky} & \multicolumn{3}{c}{Flat-Rugged} & \\  & Mean & SD & F & \(p\)-value & Mean & SD & F & \(p\)-value \\ AE 1 & 4.17 & 1.13 & & 4.17 & 1.55 & & \\ AE 2 & 4.08 & 1.25 & 0.15 & 0.81 & 4.17 & 1.43 & 0.40 & 0.67 \\ RE & 4.00 & 1.72 & & 4.46 & 1.32 & & & \\ \hline  & & \multicolumn{3}{c}{Hard–Soft †} & & & & & \\  & Mean & SD & F & \(p\)-value & & & & \\ AE 1 & 4.67 & 1.66 & & & & & \\ AE 2 & 5.00 & 1.35 & 3.35 & 0.04 & & & & \\ RE & 5.33 & 1.05 & & & & & & \\ \hline \hline \end{tabular} † † Post-hoc pairwise contrast—relative evaluation different from others, only with hard-soft \(p<0.05\).  
\end{table} 
Table 5: _Cont._added. In other words, humans seem to be better at judging material classes and material properties than they expected [57; 58; 59]. Previous studies have shown that hardness-related tactile sense is well-perceived by humans [19; 60; 61], and the repeated-measures ANOVA and post-hoc comparisons showed significant differences in scores of perceived distinguishability between two types of SD methods (AE 1 and RE). RE was found to give more distinctions among samples than AE 1. However, this indicates that their perceived distinguishability was completely wrong with the following results of affective evaluations when interacting with real samples. Humans can generally distinguish the hardness of an object by tapping it on the surface, and the frequency of vibration caused by tapping gives the cue for the perception of hardness [62]. Although the semantic pair of \"Hard-Soft\" showed a significant correlation between subjective scores on SD rating and its design parameter of softness in two evaluation methods (AE 2 and RE), the results were only valid for AE 2. Only in AE 2 did the participant perform correct evaluations consistent with the physical measures; they felt the softness of samples as their softness (as a design parameter) increased. While RE had the highest absolute value of correlation, RE is inappropriate for evaluating softness-related affect. In fact, the participants exhibited adverse discrimination among the hardness of heathers while tapping the surfaces on the vehicle instrumental panel; they actually felt hardness with samples as their softness (as a design parameter) increased. Therefore, especially in RE, the origin of vibration stimuli can be assumed to be the instrument panel itself rather than the heathers. The two semantic pairs of \"Matt-Glossy\" and \"Cooling-Warming\" showed no significant differences among all three types of SD methods. They also showed no significant correlation with the design parameters of gloss and thermal conductivity, respectively. Affects concerning glossiness (e.g., glossy, shiny, and silky) were greatly influenced by the fundamental ambiguity of the visual system under arbitrary viewing conditions, and they can be completely obscured by lighting, geometry, or other factors [63]. [PERSON] (2014) [51] revealed that inferring true physical parameters such as gloss and viscosity is often impossible. Similarly, the warm-cool feeling is associated with thermal comfort described as the human satisfaction with environmental thermal conditions, which are substantially affected by a combination of physiological, psychological, and physical factors (e.g., air temperature, air velocity, air radiant, and relative humidity) [64]. In particular, the tactile affect was heavily influenced by uncontrolled variables such as the condition of the participants and their surroundings. In conclusion, gloss and warmness were found to be affects that could not be distinguished regardless of the evaluation methods. Instead of adjusting the order of presentation of the samples, they require more careful attention in an environmental setting.