Objective: We investigated the physical attributes of an object that influence the difficulty of its assembly. Identifying attributes that contribute to assembly difficulty willprovide a method for predicting assembly complexity. Background: Despite object assembly being a widespread task, there has been insufficient research into information processing and cognition during assembly. The lack of research means that the variables that affect the performance of procedural assembly tasks with illustration only instructions are unknown. Method: In Experiment 1, seven physical characteristics (task variables) of assembly objects were systematically varied in a balanced fractional factorial and orthogonal design to create 16 abstract assemblies, which were assembled by 12 participants (6 men and 6 women aged 18-56). A second experiment (20 participants, 8 men and 12 women aged 18 to 52) involved scaled-down models of 8 real-world assemblies. Results:A clear relationship between the task variables and assembly difficulty was found in both studies, and the regression model from the first experiment was able to predict the assembly difficulty timings in Experiment 2. Conclusion: The proposed task variables are associated with assembly difficulty, and the regression analysis has shown four of the task variables to be significant predictors of difficulty. Application: Applications of this research include the use of the regression model as a tool to evaluate the difficulty of assemblies or assembly steps defined by instructions. The task variables can also be used to produce guidelines to ensure that assemblies or assembly steps are manageable.
Get full access to this article
View all access options for this article.
References
1.
Baggett, P., & Ehrenfeucht, A. (1988). Conceptualizing in assembly tasks. Human Factors, 30, 269–284.
2.
Booher, H. R. (1975). Relative comprehensibility of pictorial information and printed words in procedural instructions. Human Factors, 17, 266–277.
3.
Boothroyd, G. (1983). Design for assembly handbook. Amherst: University of Massachusetts.
4.
Cooper, L. A. (1988). The role of spatial representations in complex problems solving. In S. Schiffer & S. Steele (Eds.), Cognition and representation (pp. 53–86). Boulder, CO: Westview Press.
5.
Denis, M. (1991). Imagery and thinking. In C. Cornoldi & M. A. McDaniel (Eds.), Imagery and cognition (pp. 103–131). New York: Springer-Verlag.
6.
Drury, C. G., & Clement, M. R. (1978). The effect of area, density, and number of background characters on visual search. Human Factors, 20, 597–602.
7.
Fish, L. A., Drury, C. G., & Helander, M. G. (1997). Operator-specific assembly: An assembly time prediction assembly. Human Factors and Ergonomics in Manufacturing, 7, 211–235.
8.
Hick, W. E. (1952). On the rate of gain of information. Quarterly Journal of Experimental Psychology, 4, 11–26.
9.
Kalyuga, S., Chandler, P., & Sweller, J. (1998). Levels of expertise and instructional design. Human Factors, 40, 1–17.
10.
Madan, M., Bramorski, T., & Sundarraj, R.P. (1995). The effects of grouping parts of ready-to-assemble products on assembly time: An experimental study. International Journal of Operations and Production Management, 15, 39–49.
11.
Marcus, N., Cooper, M., & Sweller, J. (1996). Understanding instructions. Journal of Educational Psychology, 88, 49–63.
12.
Margolis, J., & Seaton, M. (1996, January 14). Working flat out. The Sunday Times, p. 14.
13.
Morrell, R. W., & Park, D. C. (1993). The effects of age, illustrations and task variables on the performance of procedural assembly tasks. Psychology and Aging, 8, 389–399.
14.
Novick, L. R., & Morse, D. L. (2000). Folding a fish, making a mushroom: The role of diagrams in executing assembly procedures. Memory and Cognition, 28, 1242–1256.
15.
Page, M., Lee, V., Grant, R., Clift, L., & Bird, R. (1996). Consumers and self assembly products - Problems and solutions. In Proceedings: 4th International Conference on Product Safety Research (pp. 1–14). Amsterdam: European Consumer Safety Association.
16.
Pedhazur, E. J. (1982). Multiple regression in behavioral research (2nd ed.). New York: CBS College Publishing.
17.
Pillay, H. K. (1997). Cognitive load and assembly tasks: Effect of instructional formats on learning assembly procedures. Educational Psychology, 17, 285–299.
18.
Prabhu, G. V., Helander, M. G., & Shalin, V. L. (1995). Effect of product structure on manual assembly performance. International Journal of Human Factors in Manufacturing, 5, 149–161.
19.
Richardson, M., Jones, G., & Torrance, M. (2004). Identifying the task variables that influence perceived object assembly complexity. Ergonomics, 47, 945–964.
20.
Shalin, V. L., Prabhu, V., & Helander, M. G. (1996). A cognitive perspective on manual assembly. Ergonomics, 39, 108–127.
21.
Shepherd, A. (1998). HTA as a framework for task analysis. Ergonomics, 41, 1537–1552.
22.
Sundarraj, R. P., Madan, M. S., & Bramorski, T. (1997). A customer focus methodology for the manufacture of ready-to-assemble products. International Journal of Operations and Production Management, 17, 1081–1097.
23.
Sweller, J. (1988). Cognitive load during problem solving: Effects on learning. Cognitive Science, 12, 257–285.
24.
Tversky, B. (2003). Structures of mental spaces: How people think about space. Environment and Behavior, 35, 66–80.
25.
Zanon, M. (2002). Writing for non-readers. Retrieved June 9, 2006, from http://www.stc.org/confproceed/2002/PDFs/STC49-00095.pdf.
