MelissaMillarKINE 4P05Human FactorAnalysis PaperDr. J.Patterson Summary of Current SystemThe current system that was analyzed was a relatively new door thatstaff 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 triggerto do so is the handle. This door isactually 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 thehandle on a door would be a good indicator of the way the door is opened, butin this case the handle indicates a pulling motion but the door actuallyrequires a pushing motion in order to open it. The poor design is surprisingconsidering the newer age of the building.
There is contrast sensitivity between the handle and thedoor itself, the handle is easily seen and easily accessible in terms oflocation 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 signindicating whether to pushor pull, they pull information from their conceptual model and from theirlong-term memory based on the type of handle provided on this particular doorand come to the conclusion that the correct action would most likely to pullthe door open. This would match the users conceptual model for this design andwould meet the 7 principles of user centered design discussed in lecture. User-centered design is anapproach to product development that grounds the process in informationcollected about the individuals and settings where products will ultimately beused (Lyon and Koerner,2016).
Byutilizing top-down processing primarily based on expectancy, just by looking atthe door and the corresponding handle, the user should be able to determinewhat they believe to be the best course of action to transition from one spaceto another. The action that the user will pull from the conceptual model willfail them in this design because although all signs lead to the door requiringa pulling motion it actually requires a pushing motion. Once the mistake isrecognized the body has to adjust the motor plan in order to open the doorcorrectly. According to Brock University’s accessibility standards, universal design is definedas: “The design of products and environments to be usable by all people, to thegreatest extent possible, without the need for adaptation or specializeddesign.” A more universaldesign could definitely be used in the new designs of this door so thatadaptations 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 thathighlight the design flaw seen in this system. A few limitations that the userhas that may highlight the design flaw applies to the idea of salience, becausethe handle of the door does not really stand out from the rest of the door asmuch as it could the user has a hard time picking it out from the rest of thedoor in time to perceiving what the correct motor plan might be to properlyopen this door. Another limitation that could also be a capability is theusers’ ability to recall information from the conceptual model and the memoryto 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 somethingwe are capable of relating a certain door handle with a certain motion that intheory should make the system easy to use if the design was a little betterregarding the trigger (handle). However, it is a limitation in this case aswell because it is not correct for the design of the door currently.
Anothercapability of the user is the ability to recognize the mistake/error andreadjust relatively quickly. The ability to see a certain handle and link itwith the motion required to open the do definitely highlights the major flaw ofthe system which is the handle. Identification and Justification This door displays a clear human factors issue in the design of thisdoor relating to the trigger of the system. The door handle (trigger) is whatcauses user error on this door, the handle can be very misleading and goesagainst the conceptual model.
The type of handle used on this door inparticular would normally indicate a pulling motion is required to open thedoor and pass through but that is not the case. Not only does the chosen doorhandle go against the conceptual model it actually is associated with thepulling motion which is why most users will chose the incorrect motor plan whenattempting to open this door. This misjudgment would be categorized as amistake error, meaning that the predicted action required was incorrect butthen realized and readjusted. There are certain handles that the human brainassociates with different motions and it is important to consider that in thedesign of the door for more effective usability and accessibility within thedesign which this system is lacking.
Something called the vision-to-actionresponse kicks in automatically causing the user to choose and perform thewrong motor plan for the door. A study done by Chang and Drury (2007), theylook at some potential issues that can occur due to mismatches between thehuman and the system when interacting with a door. A potential issue the studyaddressed was user capabilities, such as vision, cognitive capacity, andstrength. The study further suggests that if the user capabilities and thesystem do not line up there is more potentially for errors and this can be seenthrough the design of this door and the handle provided. Addressing the IssueIn order to address the human factors issue presented by the design ofthis door a few simple steps can be taken to completely eliminate orsignificantly reduce the chance of error. When designing a system such as adoor that is interacted with multiple times on a daily basis it is important tofollow the guidelines of user centered design. The current system does not, butthat can be changed by simply changing the style of handle used.
A designshould 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 theuser and the conceptual model reducing the chance of any error when trying toopen the door. By changing the handle, we would be utilizing the knowledge inthe world and in the head to configure a new system that is more effective forthe users. Another change that can be made to eliminate error can be to add avisual cue to address redundancy in this system. Adding a visual cue such asthe word “push” somewhere on the door or handle will give the user anothertrigger to use when approaching the door and determining the correct motor planto open it. In a study done by, Colavita (1974) when both visual and auditorycues were presented the visual cue dominated so it would be very beneficial toincorporate a Along with the adjustments inthe evaluation and design methods and adding aid in the visual sensory systemdepartment the principles of display can also be improved. By changing thehandle on the door to one that is familiar and automatically associated withthe pushing motion will allow for even less error as well.
Meaningful iconssuch as a hand may also be beneficial to the display and visual cues of thedoor. Kline and Beitel (1994) actually completed a study on thisconcept, the study states that the most effective door signs/symbols to put ona “push” door was a picture of a hand, accompanied by the word “push”written horizontally, this type of mixedmodality sign was one of the easiest and most recognizable systems. The mixed modality symbol will adhere to the rules of redundancy aswell by removing any doubt of how to correctly open this door. According to adifferent study done by Jaynes, the highest rate ofcompliance occurred when including photo symbols were accompanied by othercues. Whenever possible thedesigner should be trying to remove any doubt or guesswork that users have(Sannwald, 2017) Another issue that could be addressedis the contrast of the door and the handle, because the door is clear glass andthe handle is silver and is back to back with another door that looks the exactsame can make it difficult to detect, interpret and make a decision on how tointeract with this door. By making the door handle more salient as well as thewords and image of the hand these properties will be able to stand out morealleviating any doubt on how to open this door.
By making these few changes tothe door and handle the system will more effectively meet the understanding ofthe user’s conceptual model making the system much more efficient and userfriendly. Importance/Impact of Intervention By making addressing these issuesin the poor design of the system the user will be able to interact with thedoor with more ease and less confusion. These changes will allow the system tobe more supportive of the user without the user having to adapt to the system. Byremoving any doubt and reducing the options on how the door may be opened thenew design of the system would be limiting the chances of any error and theerror previously experienced prior to these changes when interacting with thisdoor.
The change in design can also help avoid more serious situations, theexample used by Lee, was if a panicked person were trying to flee thebuilding in case of a fire and they may feel trapped because they cannot figureout the correct motor plan to open the door because the trigger and theconceptual model do not match up. The importance of a design matching up with theconceptual model is crucial for success, and by addressing the few issuesdiscussed above the new design with match up with the conceptual model makingthe design more user friendly and efficient.