In this blog post, I’ll briefly explain what the SD Method is, how it measures emotions, and the areas where it’s most commonly used.
The lyrics of Busker Busker’s song “Yeosu Night Sea” include the line, “I want to tell you the beautiful story woven into the night sea of Yeosu.” By linking the longing for a former lover to the scenery of the night sea, this song evokes the emotional charm of the “night sea.” Unlike the hustle and bustle of the day, standing on a quiet beach at night, with only the sound of the waves echoing around you, creates the perfect setting for the rhythmic ebb and flow of the tides to evoke old memories and emotions. For this reason, many people associate the phrase “night sea” with images of melancholy or loneliness. Even beyond the context of the night sea, certain words or objects come to embody emotions that go beyond their original meanings. For example, dial-style telephones—which are now rarely seen—have come to embody emotions such as “nostalgia,” “analog,” and “vintage charm.”
Modern consumers value design and brand image just as much as a product’s functionality. The “emotional appeal” embodied by product design and branding plays a significant role in this trend. For quite some time now, smartphone companies—including Apple—have filled their advertisements with scenes showcasing the enjoyment consumers will experience, rather than simply explaining the products’ functions. In an era where emotion has become so important, this raises the question: Is there a way to objectively measure which design is the most elegant or which word conveys the most sophisticated feeling?
Sixty years ago, psychologists proposed a simple yet powerful evaluation method for analyzing complex, intertwined meanings. It is the Semantic Differential (SD) method. Devised by Osgood in 1950, this method is an evaluation technique for analyzing the complex meanings embedded in objects such as words, colors, and images. Known in Korean as the “semantic scale method,” its name derives from the process of having respondents rate items on a scale from 1 to 9 using multiple pairs of antonyms. Let’s now take a closer look at how the SD method works in practice.
Like a typical survey, the SD method follows a process that includes selecting survey participants, conducting the evaluation via a questionnaire, and analyzing the results. The key tools used in the SD method are pairs of antonyms, such as “traditional–modern” or “rough–smooth.” Typically, the evaluation is conducted by assigning nine rating levels between each pair of antonyms. After evaluating the subject’s emotions from multiple angles using several pairs of antonyms, the results are analyzed using a technique called factor analysis. Factor analysis is a statistical interpretation method used to identify the dominant factors inherent in multiple variables. Simply put, it is similar to the process of identifying a common underlying factor—such as “liver problems”—from various symptoms like “yellow complexion,” “indigestion,” or “chronic fatigue.” Once factor analysis is complete, conclusions can be drawn based on the evaluation’s objectives. For example, if consumers prefer a specific perfume bottle design, it is possible to identify which factors attract them. Viewed this way, the SD method appears to be the only method for hedonic evaluation. So, are there no other evaluation methods?
The three representative scaling methods widely used in statistics and the social sciences are the Likert, Thurstone, and Guttman scales. Among these, the most widely used is the Likert scale, which involves asking respondents to select from options such as “Always,” “Almost Always,” “Usually,” “Rarely,” or “Never” in response to questions like, “How often do you feel tired lately?” The Thurstone and Guttman methods were developed to address the shortcomings of the Likert scale and are used in general survey areas, such as surveys on satisfaction with one’s place of residence or product design.
However, the SD method differs from other scales in its scope of application. By using pairs of antonyms, it is well-suited for analyzing tendencies or preferences and is therefore primarily used in fields related to consumer emotional evaluation and prediction. Looking at actual research examples, the SD method is widely used in areas related to product design, such as the emotional evaluation of perfume bottle designs or the assessment of preferences based on chair shapes.
So far, we have examined the operational methods and areas of application of the SD method, focusing on how it is used to uncover the meanings embedded in products. The key features of the SD method are its use of antonyms and its ability to derive dominant elements through factor analysis. Its ability to extract a single, simple core element from a complex web of emotions will likely continue to be a sufficient reason for the design industry to maintain its interest in the SD method.
