Hello and welcome to our short presentation of our paper at the HRI 2022! It will not take long!
Longitudinal effects of robot conflict resolution strategies on compliance acceptance and trust.
We are from the Department of Human Factors and my co-authors are Philipp Hock, Johannes Kraus and Martin Baumann.
Let's start with the motivation of why one should consider human-robot conflicts.
The more autonomous robots will become the more they will have their own independent task goals.
The robot's goals, however, might contradict the user's goals. So we would have a conflict.
So it's a clash of interests with mutually exclusive goals. In our scenario, for example,
the robot wanted to clean the floor while the person was preparing a party in the kitchen
and both were under time pressure because the party would start soon.
So the question is: who is allowed priority? Is it a robot? Or is it a human?
It was a kitchen and participants had to sort items into a shelf depending
on the correct item in the box. When 20 items were left, the robot would enter the kitchen
and make its request so the person would step aside. It made its request in three different
ways: so it was either very polite and said 'Would you please step aside?' It was either
very assertive and said 'Step aside!' or it was persuasive as you can see here in the video
so it said it would not take long. As you can see here the participant decided to step aside so the
robot could clean and the robot cleaned exactly for half a minute or 30 seconds so the statement
was true with the actual cleaning duration. And then the participants continued sorting. We wanted
to investigate now which of those strategies was the most effective over several interactions.
Hereby, the Media Equation and the computers-are-social-actors paradigm
also called CASA served as basis for the development of the strategies. People
automatically treat computers, media, and robots as social actors under certain circumstances.
So the idea is that findings from social psychology can also be transferred to HCI and
HRI. However, limitations have also been found and not everything might be transferable. Limitations
to the CASA, for example, are the unique agent hypothesis. So the question is: which of those
mechanisms from social psychology can actually be transferred to human-robot interaction?
So we investigated which mechanisms can be transferred and we looked at
negotiation strategies, assertive strategies, compliance-gaining strategies, and persuasive
strategies. From those strategies, we had three of them selected for the present study because
of previous studies which I will explain now. The idea was that when the robot applies those
strategies from human-human interaction that they would be acceptable trustworthy and effective.
So how were those strategies developed? We came up with the appeal and the command strategy.
Those strategies rely on politeness or assertiveness. They have shown to have
different effects in human-robot interaction. In our previous studies, we found that command was
less effective and less accepted than the appeal but there were also other studies that found the
opposite effect. So both strategies are opposites and we wanted to see if those results also hold
over time. Additionally, we had a third strategy which is based on persuasion, and the 'that's not
all technique' which says that it will not take long to fulfill the task and tries to persuade the
other person to give priority. So in combination, we had a polite strategy, an assertive strategy,
and a persuasive strategy and we wanted to see how the acceptance, trust, and effectiveness of
those three strategies developed over time over several interactions. After the participants
had interacted with the robot, we also varied if the robot thanked the person for compliance
as reinforcement of good behavior and how this would affect the effectiveness of the strategies.
Additionally, we also had a preliminary remark. So the robot made it clear that
it wanted to clean the floor and also showed the benefits for the other person. Those strategies
were also pre-tested in previous studies and have found to set the scene for the whole experiment.
So we come to the hypotheses. Based on the different findings for appeal and command,
we assume that the appeal might be less effective because of previous studies but because it's more
polite than the command, we assumed that the appeal would be more acceptable and trustworthy
in contrast. The idea was that the persuasive strategy,
as have been shown in previous studies that persuasion might be very effective,
might be more effective acceptable and trustworthy than the other two strategies.
With regard to thanking we assumed that it might increase the compliance for all the strategies
and would also make them more acceptable and trustworthy over time. With regard to
the longitudinal investigation we have to say that we didn't find any previous studies that
looked at those strategies and how they would develop over time in regard to acceptance, trust,
and effectiveness. So we had research questions on those progressions. The idea was that maybe
the appeal might become annoying after a while so polite strategies might not be ideal for long-term
use. In contrast, it might be that an assertive strategy that is quick and easy to understand
might become more acceptable and effective over time because it's very clear what to do.
And it could be that the persuasive strategy only works once because then you already know
that it will only take half a minute and it might not be as persuasive as before.
With regard to the study design, we had a three per two per six mixed design
and 103 participants. The first between-subjects factors were the three strategies
combined with thanking or no thanking and we have six trials, so a measurement repetition,
which was a within-subjects factor. So each participant saw one of those strategies either
combined with thanking or not over six trials. We had two sessions which were separated by one
week. So we had the first two experimental trials in the first session and four continuing trials
in the second session. Each session started with a tutorial where the participants could
practice the sorting task. In the first session, we also had a robot introduction where the robot
introduced himself for five minutes which should familiarize the participants with the robot
and the robot could show its abilities. We also had a baseline measurement after the introduction
of acceptance and trust. And we had two test trials where the participants could explore
what would happen if they either went out of the way or did not go out of the
way. So the participants that were in the thanking condition also experienced the
thanking even if they might have not been compliant in the six experimental trials.
Then we come to the results. So we thought in the first hypothesis, that appeal would be less
effective than command and that diminution would be more effective than an appeal and a command.
And that thanking would increase compliance for all the strategies over time.
So we come to the first and third hypotheses. We see here that the average compliance rates
over all six trials for the different conditions combined with thanking. And what we can see here
is that the diminution strategy combined with thanking was the most effective strategy over all
six trials in comparison to the command strategy without thanking. So we saw that the diminution
strategy was the most effective strategy compared to command. However, what we could not
approve was the first hypotheses that said that appeal would be less effective than command
because as you can see here they were rather similar with regard to the compliance rates.
H3 could also only be assumed for the diminution strategy with thanking and in comparison to
command. H5 was also not true for all the strategies but only for diminution with thanking.
Then we come to the progression over time. We found that also the same strategy diminution
with thanking increased significantly over time. This was not true if diminution was not coupled
with thanking. So only for the strategy with reinforcement, we found a significant increase.
We also investigated how the compliance rates to the robot compared to a human. So we asked the
participants to imagine if they would interact with a household member if they would comply.
And we compared the compliance rate to human and robot. Here you can see the bar with the
'H' which says that it's the compliance rate to the human household member and the bar
with the 'R' is the compliance rate to the robot. You can see the different strategies
coupled with reinforcement. What you can see here is that to all the strategies the household
member received more compliance than the robot. However, for the diminution with thanking both
compliance rates did not differ significantly. So it might be that this strategy also renders
a robot equally effective as a household member. However, as the study was an online
study and this was a self-report, it would be beneficial to replicate this in a lab study.
To summarize the study investigated which conflict resolution strategies could be transferred from
the human-human interaction to human-robot interaction. We found that the diminution
strategy with thanking was a strategy that was not more acceptable but increased in trust over
time compared to the other strategies and it was also the most effective strategy.
We thank you for your attention and are looking forward to discussing with you!