# Individual Differences in Signal Perception for Takeover Request in Autonomous Driving
## 2 Related Works
### Individual Differences in Driving
Older drivers often rate their driving ability very highly but often suffer from impairment of cognitive function such as perception, attention, and memory [27]. Also, older adults have a narrower visual field [37], find it more difficult to detect high-frequency sounds [22], and are less sensitive to tactile cues [38]. They are more likely to experience a decline in cognitive function that can affect their ability to safe operate a motor vehicle, and accident rates increase after age 65. In the study of [PERSON] and [PERSON], they used multiple visual, auditory, and tactile stimuli as TOR cues and found that younger adults had faster brake reaction times when using single visual and auditory stimuli compared to older adults [29]. However, tactile signal did not make a difference. Previous research suggests that there are fundamental individual differences in how people respond to signals. Studies have explored individual differences in signal response during driving tasks, and guidelines for cues have provided a range of possibilities based on underlying cognition factors such as perception, cognition, and decision-making. However, these guidelines do not address the specific appropriateness of cues for each individual. In addition, studies focusing on TOR situations have typically examined combinations of modalities rather than different levels of stimuli, so it is unknown whether differences in response across modalities are due to cognitive differences or differences in stimulus details. Few studies have examined how manipulating sub-attribute of TOR signaling changes reaction times and whether there are interactions with personal background. Furthermore, these studies have been conducted in diverse simulation environments with different variables, such as secondary tasks, making it challenging to draw absolute comparisons unless different signals are compared within the same environment. In this research, participants were presented with visual, auditory, and tactile signals with different combinations of sub-attributes in a TOR situation, and their responses were examined. The study aimed to determine whether there is a correlation between personal background and modality and whether there are some signals that people respond better or worse to according to age, gender, and driving style. Additionally, an analysis was conducted to assess how an individual's responses vary with changes in sub-attributes of the signals. If participants' responses are linearly faster as the strength of the signal increases, then the strength of the signal would be an important factor to address in studies measuring reaction times for TOR. The study also sought to investigate whether reaction times demonstrate a linear increase, a stepwise increase, or no significant difference beyond a certain level of signal strength. Furthermore, participants' subjective perceptions of noticeability, comfort, and suitability for each signal were evaluated and compared to their behavioral responses. In summary, the study aims to address the following research questions:  
Research Question 1. Are there correlations between reaction times to visual, auditory, and tactile signals and personal background (gender, age, driving experience, etc.)? Research Question 2. Are there differences in reaction times to visual, auditory, and tactile signals and their sub-attributes based on personal background? Research Question 3. What is the relationship between subjective judgment of the signal and reaction time?