Thurstone and Triadic Whisperer
- Jul 9
- 2 min read
Next year, Thurstonian modeling will celebrate its first century. Yet, despite its deep influence on the scientific foundation of sensory science, preconceived ideas lacking theoretical support or experimental evidence endure.
Take the paradox of "discriminatory non-discriminators" (the superior performance of the ๐ฏ-๐๐๐ over the ๐๐ฟ๐ถ๐ฎ๐ป๐ด๐น๐ฒ method), solved by ๐๐ณ๐ช๐ซ๐ต๐ฆ๐ณ๐ด back in 1979. Even though it was resolved by simply using the core assumptions of ๐ง๐ต๐๐ฟ๐๐๐ผ๐ป๐ถ๐ฎ๐ป ๐๐ต๐ฒ๐ผ๐ฟ๐, decades of industry and academic practice have often attributed this 3-AFC advantage simply to "the additional piece of information" (knowing the dimension of the difference).
For instance:
ย โข ๐๐๐ ๐๐ฅ๐๐๐๐ wrongly stipulates: โPeople perform better in a three-alternative forced choice task when told in advance which dimension of the stimulus to attend to.โ
ย โข Similarly, current ๐๐๐๐จ like Gemini give an imprecise explanation, claiming that knowing the attribute "drastically reduces the mental workload" compared to evaluating all dimensions in a Triangle test.
Recent research (link in comments) shows this is ๐ก๐ข๐ง why the 3-AFC is more powerful.
In a recent study, when panelists were explicitly told the dimension of the difference in a triangle test (a "specified triangle"), this additional information did not result in an increase in their ability to discriminate between lemon-based beverages:
Average Performances:
ย โข ๐ฏ-๐๐๐: 63% correct ๐ ๐ฅโ = 1.0
ย โข ๐ง๐ฟ๐ฎ๐ฑ๐ถ๐๐ถ๐ผ๐ป๐ฎ๐น ๐๐ฟ๐ถ๐ฎ๐ป๐ด๐น๐ฒ: 43% correct ๐ ๐ฅโ = 1.1
ย โข ๐ฆ๐ฝ๐ฒ๐ฐ๐ถ๐ณ๐ถ๐ฒ๐ฑ ๐๐ฟ๐ถ๐ฎ๐ป๐ด๐น๐ฒ: 43% correct ๐ ๐ฅโ = 1.1
โWhisperingโ the nature of the difference to the panelist during a triangle test ๐ฑ๐ถ๐ฑ ๐ป๐ผ๐ ๐ฐ๐ต๐ฎ๐ป๐ด๐ฒ the cognitive decision rule or facilitate discrimination.
These practical results powerfully support Thurstonian theory and illustrate the ๐ฉ๐ง๐ช๐ ๐ซ๐๐ก๐ช๐ of mathematical decision models in sensory science.
In upcoming posts, we will show how this theory allows us to reliably predict consumer opinion directly from internal panel results.
What about you? What role does Thurstonian theory play in your research programs?
