Introduction
The term affordance was introduced by the ecological psychologist James Gibson (1979) to describe the interactions between an actor and an object as action possibilities with respect to the actor. Nowadays, affordance-based design (ABD) is widely utilized to improve usability, minimize human errors and decrease their associated risks (Maier & Faded, 2009). The applications are in the fields of forensic science (Hartman, Whetsel Borzendowski, & Campbell, 2019), user interface design, artificial intelligence (Mi, Tang, Deng, Görner, & Zhang, 2019), and workplace innovation (Durugbo, 2020, in press). However, studies on affordances had been normally focusing on transiently altered body properties or aging. People with altered body property due to chronic diseases were largely omitted (Konczak, Meeuwsen, Cress, 1992; Masoudi, Fadel, Pagano, & Elena, 2019). Here, we propose a quantitative, mechanistic study to explore the impact of a chronic disease, namely obesity, on perceived affordance.
Obesity affected 93.3 million United States adults (39.8% of the U.S. population) from 2015 to 2016 (Hales, Carroll, Fryar, & Ogden, 2017). It has been linked to increased risk of several diseases such as stroke, cancer, cardiovascular disease, hypertension, type II diabetes mellitus, and mental health problems (Xu, & Lam, 2018). It has also been shown that being overweight or obese can decrease cognitive abilities (Steenbergen, & Colzato, 2017), increase mechanical constraints, impair visual motor coordination (Gaul, Mat, O'Shea, & Issartel, 2016), and alter balance and movement control (Teasdale et al., 2013). The proposed research will utilize an ergonomics approach to understand the impact of obesity and overweight on perceived affordance. More specifically, the classic stair climbing task will be performed to assess the perceived affordances of people with different Body Mass Indexes (Warren, 1984). This study can be a proof of concept to characterize the altered perception due to chronic diseases such as obesity. It would also provide guidance for designing more inclusive tools and working environments for people suffering from these prevalent chronic conditions such as obesity.
Statement of Research Questions
Are there significant differences in perceived affordances in visually guided stair-climbing tasks among adults aged from 20 to 40 years in the Greater Philadelphia area with a Body Mass Index (BMI) below 25, from 25 to 30, and above 30?
- Aim 1: Are there significant differences in the visually perceived critical riser heights among adults aged from 20 to 40 years with different BMIs?
- Aim 2: Are there significant differences in the achieved riser heights among adults aged from 20 to 40 years with different BMIs?
- Aim 3: Are there significant differences in the correlations between perceived and achieved riser heights among adults aged from 20 to 40 years with different BMIs?
Participants
Participants will be recruited by information sessions, flyers, and posters at local community centers, commercial fitness centers, and local municipal facilities. All participants shall no previous history of neurologic or Psychiatric disorders on file. Also, they should have normal or corrected to normal vison. In addition, all participants shall be from 20 to 40 years old with no sign of mild cognitive impairment or dementia according to their age (age-specific test scores can be assessed by the DemTect) (Kalbe el al, 2004). Furthermore, all participants need to have a body mass index (BMI) above 18.5 and a height range from 155 cm to 185 cm. Participation in the study will be compensated financially upon study completion.
This study sample consists of participants with a BMI from 18.5 to 25, from 25 to 30, and above 30 according to definitions of overweight and obesity (Centers for Disease Control and Prevention, 2017). The goal is to recruit 20 individuals for each BMI category. Each BMI group should have comparable characteristics (such as gender, height, weight, and age). In total, 60 individuals who meet the inclusion criteria will be recruited.
Materials and Equipment
The English version of the DemTect test will be used to if any participant displays any sign of mild cognitive impairment or dementia that would affect the test result. A standardized eye chart will be used to determine if participants have normal or corrected-to-normal vision. Anthropometric measures will be obtained using a hand-held goniometer, a weight scale, and a stadiometer.
Twelve sets of adjustable stairs will be set up with random order in a semicircle with a 15-feet radius (Konczak, Meeuwsen, & Cress, 1992). The riser height of each stairs will be unique and ranging from 55% to 110% of each participant’s leg length. Each stairway will have two steps. All the stairs will be in black color, and 1 inch-wide white tapes will mark the back and the front edge of each step. One number from 1 to 12 will be assigned to each stairs randomly to facilitate identification. The identification number will be printed out in 6 cm by 10 cm large white paper and taped to the lower right corner of each set of stairs.
The experiment data will be recorded with SuperLab 5 Electronic Lab Notebook System (Cedrus Corporation).
Procedures
After initial eligibility screenings and informed consent procedures, measurement of physical characteristics of each participant will be conducted. This includes to measure and record heights of standing and sitting, length of lower leg, and length of upper leg.
Following above measurement, the adjustable stair displays will be adjusted according to the leg length of each individual participant. Each participant will be led to the center of the display semicircle, so each set of stairs is in the same position with respect to the participant. The participant will be asked to identify the staircase with the largest rise height that they think they could climb bipedally. The identification number of the initially identified staircase, and its corresponding riser height, will be recorded as the perceived maximum riser height (as a percentage of the participant’s leg length). Then, each participant will attempt to climb the identified stairs. If the first attempt is unsuccessful, participants will attempt to climb the next lower staircase until they succeed. If successful in their first try, participants will attempt to ascend the next higher stair until they fail. The greatest riser height of the staircase that is climbed successfully will be recorded as the achieved maximum riser height (as a percentage of the participant’s leg length).
Analysis
SPSS Statistics 25 software (IBM) will be utilized to analyze anthropometric and behavioral data. Statistical significance will be determined by reporting two-tailed p-values (p < .05). An ANOVA will be performed to determine if there is any significant group difference in perceived maximum riser height and achieved maximum riser height measurement, between normal (BMI>18.5, 25, 30) groups.
To determine the impact of BMIs on the correlation between perceived and achieved maximum riser height, regression analysis will be performed between perceived maximum riser height and achieved maximum riser height for each BMI group. If all correlations are found to be statistically significant, a Fisher’s r to z transformation will be performed to determine if there is a significant difference between those correlation coefficients. All correlation coefficients used here will be determined with data collected in the proposed study. The analysis is predicted to be a text-book linear regression procedure that may or may not be the same as previous studies (Yan, & Su, 2009).
Human Subjects
This project does involve human subject according to Human Subject Research guidelines (45 CFR 46, 2009). The proposed systematic investigation is research as its findings can contribute to generalizable knowledge. The focus of this study is to investigate the impact of BMI on the perceived affordance of individual human subjects. Accordingly, this study will be conducted according to the Protection of Human Subjects (45 C. F. R. 46, 2009). Thus, study will only commence upon Institutional Review Board (IRB) approval. Furthermore, informed consents form will be provided to all participants, informed consent procedure will be conducted accordingly. All private information and other data from all participants will be kept safe and confidential. We subscribe to the ethical principles underlying the conduct of research involving human subjects as set forth in the Belmont Report (1978). We are also in compliance with the Common Rule in the Code of Federal Regulations (45 CFR 46, 2009) on the Protection of Human Subjects.
References
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