Drivers' reactions to a semi-autonomous technology for assisted parallel parking system were evaluated
in a field experiment. A sample of 42 drivers balanced by gender and across three age groups (20e29, 40
e49, 60e69) were given a comprehensive briefing, saw the technology demonstrated, practiced parallel
parking 3 times each with and without the assistive technology, and then were assessed on an additional
3 parking events each with and without the technology. Anticipatory stress, as measured by heart rate,
was significantly lower when drivers approached a parking space knowing that they would be using the
assistive technology as opposed to manually parking. Self-reported stress levels following assisted parks
were also lower. Thus, both subjective and objective data support the position that the assistive technology
reduced stress levels in drivers who were given detailed training. It was observed that drivers
decreased their use of turn signals when using the semi-autonomous technology, raising a caution
concerning unintended lapses in safe driving behaviors that may occur when assistive technologies are
used.