Spatial Visualization Ability and Impact of Drafting Models: A Quasi Experimental Study

A quasi experimental study was done to determine significant positive effects among three different types of visual models and to identify whether any individual type or combination contributed towards a positive increase of spatial visualization ability for students in engineering technology courses. In particular, the study compared the use of different visual models a 3D printed solid object, a 3D computer generated drawing and a 2D drawing. Introduction It is recognized that the ability to visualize is an important tool required of engineers in order to function effectively (Deno, 1995; Miller, 1990; Pleck, 1991; Sorby & Baartmans, 2000). More specific, visualization of problems is critical for success in engineering education (Sorby & Baartmans, 2000), and for that reason spatial abilities have been used as a predictor of success in several engineering and technology disciplines (Strong & Smith, 2001). However, these abilities are not determined genetically, but rather a result of a long learning process. It has been shown by several studies that some type of intervention, whether a short course or a semester long course, can improve spatial abilities in students who score low on tests in this area (Hsi, Linn, & Bell, 1997; Martín-Dorta, Saorín, & Contero, 2008; Sorby, 2001). For this study, the following was the primary research question. Is there a difference between the impact of model type (2D drawing, 3D computer generated drawing, 3D printed object) on spatial visualization ability? The following hypotheses will be analyzed to attempt to find a solution to the research question. The hypotheses that guided this study were: H0: There will be no difference in spatial visualization ability between the impact of model type (2D drawing, 3D computer generated drawing, 3D printed object). HA: There will be significant difference in spatial visualization ability between the impact of model type (2D drawing, 3D computer generated drawing, 3D printed object). Review of Literature According to Piagetian theory, an individual acquires spatial visualization ability through three distinct stages of development (Bishop, 1978). During the first stage, children Engineering Design Graphics Journal (EDGJ) Copyright 2014 Spring 2014, Vol. 78, No. 2 ISSN: 1949-9167 http://www.edgj.org ___________________________________________________________________ 2 acquire topological spatial visualization skills with the ability to discern an object’s topological relationship with other objects. During the second stage of development, projective representation is acquired and children can conceive what an object will look like from a different perspective. At the third stage of spatial visualization development, the individual learns to combine projective abilities with the concept of measurement. Due to the reduced amount of instructional time given for engineering graphics content in many engineering and technology programs, faculty have expressed concern that students’ ability to visualize 3D parts from 2D drawings is not being developed as well as in the past (Branoff, T. J. & M. Dobelis, 2013; Branoff, 2007; Clark & Scales, 2000; Meyers, 2000). To measure an individual’s spatial ability, a plethora of standardized tests are available. The most commonly used tests include: a) The Purdue Spatial Visualization Test: Rotations (PSVT:R), devised to test a person’s ability at the second stage of development (Sorby, 2005). b) The Mental Rotation Test (MRT) a test designed to assess a person’s ability to visualize rotated solids (Sorby, 2005). c) The Differential Aptitude Test: Space Relations (DAT:SR) consists of 50 items and with a role to test spatial ability (Monahan, Harke and Shelley, 2008). d) The Mental Cutting Test (MCT) that requires individuals to create a split view of an object; therefore, forcing to visualize and choose the correct cross-section among five alternatives (Tsunumi, 2004). Several studies have been conducted to examine the usefulness of an engineering graphics literacy test (Branoff & Dobelis, 2012a, 2012b, 2012c; T. J. Branoff & M. Dobelis, 2013) and some of them have proven to be great predictors of an individual’s ability to visualize (Kelly, Clark, & Branoff, 2013).Some of the factors that have been identified by various graphics education researchers are spatial visualization, spatial relations, spatial orientation, spatial cognition, spatial intelligence, spatial ability, and visualization (Hartman & Bertoline, 2005; MartinDorta, Saorin, & Contero, 2008; Miller & Bertoline, 1991; Sorby, 1999a). According to Bodner and Guay (1997) two factors emerged from spatial ability research: spatial orientation, which involves not being puzzled by changes in visual inputs, and spatial visualization, which involves the ability to manage visual input components (Kelly, 2012). Eliot and Smith (1983) showed factors, such as spatial relations, in the context of mental rotation of objects, spatial orientation as the understanding of how an object would appear from a different perspective, and visualization from a surface development context (Kelly, 2012) According to Juhel (1991) the focus is on three factors: spatial orientation, which determines how an object Engineering Design Graphics Journal (EDGJ) Copyright 2014 Spring 2014, Vol. 78, No. 2 ISSN: 1949-9167 http://www.edgj.org ___________________________________________________________________ 3 will appear from a different position; spatial visualization, which involves the mental transformation of an object; and speeded rotation, which is the mental rotation of objects (Kelly, 2012). In recent years, 3D spatial abilities have received much attention. Several studies have involved different interfaces to attempt to manipulate a person's understanding of 3D space (Carriker, 2009).Cockburn (2004) asked whether or not a person would have a better spatial memory if they were given a 3D representation of the object's location. For the specific study, the user is not allowed to move; it is only a simple comparison of perspective effects in the displays (Carriker, 2009). Cockburn (2004) also added visual cues that gave the illusion of a 3D object, including shadows, lighting and size, to see if individuals could recall the 3D objects better than their 2D counterparts. He found that there were no significant differences between the averages of the 2D and 3D conditions. Authors, Tan, Gergle, Scupelli, & Pausch (2004) performed a study that was designed to examine the effects of physical display size on an individual’s cognitive strategy and performance on an interactive 3D navigation task (Carriker, 2009). Comparable to the prior study by Cockburn, Tan et al. attempted to analyze 3D spatial ability using different displays. However, they also addressed whether that performance is directly affected by the task being interactive or not. Tan et al. (2004) attempted to examine not only the implications of the display, but the effect on the subject when allowed different means of interaction with the 3D world. In addition, several researchers have suggested that spatial ability can be enhanced and taught by some instructional designs (Alias, Black, & Gray, 2002; Kwon, 2003; Lajoie, 2003; Potter & Merwe, 2001; Woolf, Romoser, Bergeron, & Fisher, 2003). Many works demonstrated that instructions using computer-based 3D visualizations can provide learners with adequate spatial experiences for developing their spatial ability (Kwon, 2003; Woolf et al., 2003). However, few empirical studies have established the causal relationships in greater depth (Wang, Chang & Li, 2006).Moreover; few studies have explored the effects of two-dimensional (2D) versus three dimensional (3D) media representations on the influence of the spatial ability of undergraduate students (Wang, Chang & Li, 2006). Based on this research, it is clear that changing the software or hardware has a high correlation to a student's understanding of 3D space. This encourages future research to find the most efficient tools to improve 3D spatial visualization ability for all students. Methodology A quasi-experimental study was selected as a means to perform the comparative analysis of spatial visualization ability during the fall semester of 2013. The study was conducted in an engineering graphics course, MET 120 (Computer Aided Drafting), offered at Old Dominion University as a part of the Engineering Technology program. The participants from the study are shown in Table 1. From the 54 students, 12 were Engineering Design Graphics Journal (EDGJ) Copyright 2014 Spring 2014, Vol. 78, No. 2 ISSN: 1949-9167 http://www.edgj.org ___________________________________________________________________ 4 females and 18 were African American and using a convenience sample there was a near equal distribution of the participants between the three groups. Table 1. Research Design Methodology Group 1 n1=20 MCT Sketch from 2D drawing Group 2 n2=16 MCT Sketch from 3D image Group 3 n3=18 MCT Sketch from 3D object The engineering graphics course emphasized “hands on” practice using 2-D and 3D AutoCAD software in the computer lab, along with the various methods of editing, manipulation, visualization and presentation of technical drawings. In addition, the course included the basic principles of engineering drawing/hand sketching, dimensions and tolerance principles. The students attending the course during the fall semester of 2013 were divided in to three groups according to the section of the course that they chose to participate the semester prior to the study. The three groups (n1=20, n2= 16 and n3=18 with an overall population of N = 54) were presented with a visual representation of an object (drafting model) and were asked to create a sectional view. The first group (n1) received a 2D drawing of the cone (see Figure.1), the second group (n2) received a 3D PC generated image of the cone (see Figure. 2) and the third group (n3) received a 3D printed cone using a 3D rapid prototyping machine (see Figure. 3). Figure1. 2D Drawing Figure 2. 3D Computer Figure 3. 3D Printed Object Using Generated Drawing Additive Technology In addition, all groups were asked to complete the MCT instrument 2 days prior to the completion of the sectional view drawing to identify level of visual ability and show Engineering Design Graphics Journal (EDGJ) Copyright 2014 Spring 2014, Vol. 78, No. 2 ISSN: 1949-9167 http://www.edgj.org ___________________________________________________________________ 5 equality between the three groups. According to Nemeth and Hoffman (2006) the MCT has been widely used in all age groups. The “standard MCT” consists of 25 problems. The Mental Cutting Test (hereafter MCT), a sub-set of the CEEB Special Aptitude Test in Spatial Relations has been used by Suzuki et al.to measure spatial abilities in relation to graphics curricula (Tsunumi, 2004). In each problem, subjects are given a perspective drawing of a test solid, which is to be cut with a hypothetical cutting plane. Subjects are then asked to choose one correct cross section from among 5 alternatives. There are two categories of problems in the test (Tsutsumi, 2004). Those of the first category are called `pattern recognition problems', in which the correct answer is determined by identifying only the pattern of the section. The other are called `quantity problems' or `dimension specification problems', in which the correct answer is determined by identifying not only the correct pattern but also the quantity in the section, e.g., the length of the edges or the angles between the edges (Tsutsumi, 2004). Upon completion of the MCT the instructor of the course placed the 2D drawing, 3D computer generated image and 3D printed object in a central location in the classroom (the three groups were positioned in to three different rooms) and asked the students to create a sectional view of the cone. The engineering drawing that was used in this research was a sectional view of a cone which had different levels of different materials. These levels had different colors. Sectional views are very useful engineering graphics tool, especially for parts that have complex interior geometry. Sections are used to clarify the interior construction of a part that cannot be clearly described by hidden lines in exterior views (Plantenberg 2013). By taking an imaginary cut through the object and removing a portion, the inside features could be seen more clearly. Students had to mentally discard the unwanted portion of the part and draw the remaining part. The rubric used included the following parts: 1) use of section view labels; 2) use of correct hatching style for cut materials; 3) accurate indication of cutting plane; 4) appropriate use of cutting plane lines; and 5) appropriate drawing of omitted hidden features. Maximum score for the drawing was 6 points. Data Analysis Analysis of MCT Scores The first method of data collection involved the completion of the MCT instrument prior to the treatment to show equality of spatial ability between the three different groups. The researchers graded the MCT instrument as described in the guidelines of the MCT creators. A standard paper-pencil MCT was conducted, in which the subjects were instructed to draw intersecting lines on the surface of a test solid with a green pencil before selecting alternatives. The maximum score that can be received on the MCT is 25 and as it can be seen in Table 2, n1 had a mean of 21.47, n2 had a mean of 19.76 and n3 had a mean of 21.37. There was no significant difference between the three groups as far as spatial ability as measured by the MCT instrument. Engineering Design Graphics Journal (EDGJ) Copyright 2014 Spring 2014, Vol. 78, No. 2 ISSN: 1949-9167 http://www.edgj.org ___________________________________________________________________ 6 Table 2. MCT Descriptive Results 95% Confidence Interval for Mean N Mean SC Std Error Lower Bound Upper Bound 2D 16 21.471 8.02 3.213 13.629 17.513 3D PC 20 19.766 6.121 2.096 14.169 19.164 3D Solid 18 21.314 6.945 2.390 18.049 21.379 Total 54 21.85 6.87 2.56 16.28 19.352