Hello everyone, and welcome to this presentation.
I am Philippe Schmid
I am a PhD student in the Loki research group at Inria
and I'm going to talk about a project we did
with Andy Cockburn, Sylvain Malacria, and Mathieu Nancel
about what we call Interaction Interferences
You may have already experienced situations
where you are about to perform an action, like clicking an unread email
and at the very last moment, the interface changes, it fetches new mail for example.
But you still end up clicking on what is now a different email
because even though you may have noticed the change, you couldn't refrain
from performing that planned click
This phenomenon can be found in other situations
for instance when a popup window appears right before you click on a link
covering it and thus catching the click
We call these phenomena interaction interferences
They are Changes in the interface that occur right before a user performs a physical action
and too late for them to interrupt it
This happens because events are interpreted in the context of the current system state
regardless of how recent it is
Changing the state even 1 ms before receiving the click
and still interpreting the event as being issued in the context of this new state
is totally fine for the system
Yet it is highly unlikely that this was the user's intention
Both the computers, and us users, need time to process information
We thus need to take this reality into account
We first set out to qualify this family of issues
so we created an online survey, discussing examples of experienced interaction interferences
their frequency, how severe their outcome was, and how frustrating people felt about it
It came out that participants could easily find examples of such phenomena
and even though those interferences are generally of minor consequences
they cause trouble and are a source of annoyance and frustration
Among the most severe ones, we had portions of a password appearing in plain text after another window took focus
texting the wrong contact, or calling someone by mistake
Our next step was to start characterizing this phenomenon
by estimating the minimum reaction time to inhibit one's action in a common context
Most of our participants' examples were related to pointing and clicking
so we focused on this task
There exists related work on that topic in neuroscience and HCI
measuring for instance the minimum delay under which a user can't refrain from starting a pointing motion
or from typing a key
However, in the context of virtual target acquisition
interference issues do not result from moving the cursor but from clicking at the end of that movement
and that distinction has not been previously studied in HCI
We adapted an experimental protocol from neuroscience to a virtual pointing task
Participants were asked to click a green target as fast as possible
However, in a random 15% of the trials, the target became red shortly after it appeared
in which case the participants were instructed to refrain from clicking
In those so-called "stop-trials", we needed to control the delay between that red "stop signal" and the time of the click
so we had to estimate the moment where the click would happen
The specifics of this process are described in details in the paper
Our main results consist in a profile of successful click inhibition
They indicate that, when given 350 ms to inhibit a click at the end of a pointing motion
users manage to refrain from clicking about 50% of the time
And at 600ms, we get close to 100%
An interesting fact about these success rates is that there seems to be no impact of the pointing task's difficulty in Fitts terms
So what does that mean?
Basically, input events occurring after a state change on their target can for example be considered interferences
say 400 ms or less after the change occurred
And simply flagging these inputs as hazardous to the user might already avoid annoyance and frustration
our next steps will involve solutions to prevent or mitigate the resulting errors
Thank you for your attention, I'll be happy to answer questions, now, and later by email at: philippe dot schmid at inria dot fr