Melissa grounds the process in information collected about

Melissa
Millar

KINE 4P05

Human Factor
Analysis Paper

Dr. J.

Patterson

 

 

 

 

 

 

 

 

Summary of Current System

The current system that was analyzed was a relatively new door that
staff and students interact with many times a day in Cairns at Brock university.

The function of this system is to transition between a space, and the trigger
to do so is the handle.  This door is
actually a “push to open” door,
however the handle provided on this particular door contradicts that indication.

This contradiction causes confusion and difficulty to the users, typically the
handle on a door would be a good indicator of the way the door is opened, but
in this case the handle indicates a pulling motion but the door actually
requires a pushing motion in order to open it. The poor design is surprising
considering the newer age of the building. There is contrast sensitivity between the handle and the
door itself, the handle is easily seen and easily accessible in terms of
location on the door but it is lacking a visual cue such as a sign indicating “push” or “pull”.  When an individual approaches this door and sees the lack of sign
indicating whether to push
or pull, they pull information from their conceptual model and from their
long-term memory based on the type of handle provided on this particular door
and come to the conclusion that the correct action would most likely to pull
the door open. This would match the users conceptual model for this design and
would meet the 7 principles of user centered design discussed in lecture. User-centered design is an
approach to product development that grounds the process in information
collected about the individuals and settings where products will ultimately be
used (Lyon and Koerner,2016). By
utilizing top-down processing primarily based on expectancy, just by looking at
the door and the corresponding handle, the user should be able to determine
what they believe to be the best course of action to transition from one space
to another. The action that the user will pull from the conceptual model will
fail them in this design because although all signs lead to the door requiring
a pulling motion it actually requires a pushing motion. Once the mistake is
recognized the body has to adjust the motor plan in order to open the door
correctly. According to Brock University’s accessibility standards, universal design is defined
as: “The design of products and environments to be usable by all people, to the
greatest extent possible, without the need for adaptation or specialized
design.” A more universal
design could definitely be used in the new designs of this door so that
adaptations are not needed.

Task Analysis:

Function

Task

Subtask

Cognitive
Demand

Motor
Demand

Sensory
Demand

Outcome/Duration

Transition
from one space to another

Recognize the door and the
handle on the door

 

Take note of the type of handle
and all of the different characteristics

 

 

 

 

Reach for the door handle

Decide whether to push or
pull the handle

Recall from Long Term
Memory that this type of handle indicates the door should be pulled

Prepare to reach for the
handle to pull it

 

The outcome of this after
recalling from Long Term Memory is that a pull is the ideal option.

 

 

Deciding to pull handle.

Using Top-Down processing (expectancy), to recall that this handle
corresponds with pulling motion
Plant feet on floor, activating the quadriceps muscles, hamstring muscles, calf muscles, gluteal group

Prepare to reach for the
handle to begin pulling. R

Activate  muscles to keep balance while pulling on the
door

 

Ready to open the door

 

 

step back with non-dominant
foot

Step back to open the door
without falling over

Lower body muscles involved
in walking will activate and provide the necessary motion

 

To step out with the other
leg

 
 

 

Rotate the trunk about 15
degrees towards your non-dominant leg

This movement will prepare
the shoulder to flex and reach for the door handle. It is an automatic
process to begin the next phase

Engage the rectus
abdominis, as well as internal/external obliques to provide the trunk with
rotation

 

Rotation of the trunk,
taking less than a second  

 

 

With the palm facing
inwards, flex the shoulder of the dominant hand (opposite from leg) about 80
degrees

 

Engage pectoralis major,
anterior deltoid as well as the biceps to bring the arm up and shoulder into
flexion

 

Shoulder flexion, taking
less than a second  

 

Grab onto the handle

Place the palm onto the
handle

 

 

Your haptic system will
feel the smoothness of the handle and prepare to grab

Grabbing the handle, taking
less than a second  

 

Pull the handle to initiate
the opening

Recall from Long Term
Memory the amount of force needed to pull door open

Requires attention to
ensure that the door is not pulled with too little or too much force
Research states 22.2 N is  the maximum required force to open an
interior door This is the force needed to continue the movement of the door,
not the initial force needed to overcome the inertia of the door (1)

Activate upper body muscles

 

Pulling on the handle
resulting in no movement, taking less than a second. Mistake is acknowledged
and adjusted

 

Readjust motor plan to get
the door open

Prepare body to push on
door handle

Recall the amount of force
needed to open the door with pushing motion opposed to pulling
 
Research shows that much
like a pull, for a push the maximum required force needed is 22.2N (1)

Activate both upper and
lower body muscle groups

Visual system will see that
the door is opening

For the individual to
readjust their motor plan it will take little time. After process of
elimination pushing motion is required.

 

 

Step with the front leg to
walk through door

Attention is now focused on
the door opening, and the body can begin to pass through the frame, keeping
contact with the handle to continue to hold the door open.

Using walking muscles to
pass through the frame

 Foot contact will continue with the ground,
while walking and hand remain on the door to keep it open

This motion will be about 1
– 2 second to allow the body to get through the door

 

 

Remove hand and any force
still being applied to the door

Once the door is fully
opened, the handle can be released and the user can pass fully through the
door

The muscles used to hold
open the door can relax and the legs can continue to walk

 

Releasing the grip, taking
less than a second  

 

 

Return hand and arm back to
the side of the body where it naturally falls

 

Relax the arm to the
individuals comfortable resting position

 

Returning the shoulder back
to its location beside the body will take about 200ms

 

 

Human Capabilities and Limitations

 

As the user of there are certain capabilities and limitations that
highlight the design flaw seen in this system. A few limitations that the user
has that may highlight the design flaw applies to the idea of salience, because
the handle of the door does not really stand out from the rest of the door as
much as it could the user has a hard time picking it out from the rest of the
door in time to perceiving what the correct motor plan might be to properly
open this door. Another limitation that could also be a capability is the
users’ ability to recall information from the conceptual model and the memory
to see the type of handle on the door and associate it with a particular movement.

This can be both a limitation and capability in this scenario because it is something
we are capable of relating a certain door handle with a certain motion that in
theory should make the system easy to use if the design was a little better
regarding the trigger (handle). However, it is a limitation in this case as
well because it is not correct for the design of the door currently. Another
capability of the user is the ability to recognize the mistake/error and
readjust relatively quickly. The ability to see a certain handle and link it
with the motion required to open the do definitely highlights the major flaw of
the system which is the handle.

 

Identification and Justification

 

This door displays a clear human factors issue in the design of this
door relating to the trigger of the system. The door handle (trigger) is what
causes user error on this door, the handle can be very misleading and goes
against the conceptual model. The type of handle used on this door in
particular would normally indicate a pulling motion is required to open the
door and pass through but that is not the case. Not only does the chosen door
handle go against the conceptual model it actually is associated with the
pulling motion which is why most users will chose the incorrect motor plan when
attempting to open this door. This misjudgment would be categorized as a
mistake error, meaning that the predicted action required was incorrect but
then realized and readjusted. There are certain handles that the human brain
associates with different motions and it is important to consider that in the
design of the door for more effective usability and accessibility within the
design which this system is lacking. Something called the vision-to-action
response kicks in automatically causing the user to choose and perform the
wrong motor plan for the door. A study done by Chang and Drury (2007), they
look at some potential issues that can occur due to mismatches between the
human and the system when interacting with a door. A potential issue the study
addressed was user capabilities, such as vision, cognitive capacity, and
strength. The study further suggests that if the user capabilities and the
system do not line up there is more potentially for errors and this can be seen
through the design of this door and the handle provided. 

 

Addressing the Issue

In order to address the human factors issue presented by the design of
this door a few simple steps can be taken to completely eliminate or
significantly reduce the chance of error. When designing a system such as a
door that is interacted with multiple times on a daily basis it is important to
follow the guidelines of user centered design. The current system does not, but
that can be changed by simply changing the style of handle used. A design
should fit or support the user without the user having to adapt to the system,
so by changing the handle on this door the system will much better support the
user and the conceptual model reducing the chance of any error when trying to
open the door. By changing the handle, we would be utilizing the knowledge in
the world and in the head to configure a new system that is more effective for
the users. Another change that can be made to eliminate error can be to add a
visual cue to address redundancy in this system. Adding a visual cue such as
the word “push” somewhere on the door or handle will give the user another
trigger to use when approaching the door and determining the correct motor plan
to open it. In a study done by, Colavita (1974) when both visual and auditory
cues were presented the visual cue dominated so it would be very beneficial to
incorporate a

 Along with the adjustments in
the evaluation and design methods and adding aid in the visual sensory system
department the principles of display can also be improved. By changing the
handle on the door to one that is familiar and automatically associated with
the pushing motion will allow for even less error as well. Meaningful icons
such as a hand may also be beneficial to the display and visual cues of the
door. Kline and Beitel (1994) actually completed a study on this
concept, the study states that the most effective door signs/symbols to put on
a “push” door was a picture of a hand, accompanied by the word “push”
written horizontally, this type of mixed
modality sign was one of the easiest and most recognizable systems. The mixed modality symbol will adhere to the rules of redundancy as
well by removing any doubt of how to correctly open this door. According to a
different study done by Jaynes, the highest rate of
compliance occurred when including photo symbols were accompanied by other
cues. Whenever possible the
designer should be trying to remove any doubt or guesswork that users have
(Sannwald, 2017) Another issue that could be addressed
is the contrast of the door and the handle, because the door is clear glass and
the handle is silver and is back to back with another door that looks the exact
same can make it difficult to detect, interpret and make a decision on how to
interact with this door. By making the door handle more salient as well as the
words and image of the hand these properties will be able to stand out more
alleviating any doubt on how to open this door. By making these few changes to
the door and handle the system will more effectively meet the understanding of
the user’s conceptual model making the system much more efficient and user
friendly.

 

Importance/Impact of Intervention

 

By making addressing these issues
in the poor design of the system the user will be able to interact with the
door with more ease and less confusion. These changes will allow the system to
be more supportive of the user without the user having to adapt to the system. By
removing any doubt and reducing the options on how the door may be opened the
new design of the system would be limiting the chances of any error and the
error previously experienced prior to these changes when interacting with this
door. The change in design can also help avoid more serious situations, the
example used by Lee, was if a panicked person were trying to flee the
building in case of a fire and they may feel trapped because they cannot figure
out the correct motor plan to open the door because the trigger and the
conceptual model do not match up. The importance of a design matching up with the
conceptual model is crucial for success, and by addressing the few issues
discussed above the new design with match up with the conceptual model making
the design more user friendly and efficient.