The placebo of place: terroir effects in the blind and sighted quality assessments of South African varietal wines.

摘要

Purpose: Proceeding from previous studies of South African terroir that have sought to distinguish and authenticate quality wines of origin by virtue of their chemistry, this study sought to differentiate wine-producing territories by hedonic quality. Design: Using a database of paired sighted and blind tastings of popular South African cultivars (Cabernet, Chardonnay, Chenin Blanc, Merlot, Pinotage, Pinot Noir, Sauvignon Blanc and Shiraz) during January 2000-January 2006, a series of 16 multiple linear regression models was developed to explain blind and sighted quality ratings from the perspective of terroir, whilst controlling for production-side factors of cost and scale. Findings: This study: (1) revealed how certain wine appellations produce a particular and predictably consistent level of wine quality, while others do not; (2) illustrated the extent to which blind and sight-based versions render different combinations of terroir effects; and (3) demonstrated that while the former was stunted by its limited statistical significance and a crude level of ward differentiation, the latter revealed a far clearer, richer and more finely calibrated suite of terroir. The sighted approach was, however, flawed by an inherent neurological bias fuelled by the prior knowledge of each ward-of-origin and a number of other extrinsic cues proxied by the sighted quality metric. These findings appear consistent with Priilaid's work (2006) on wine's placebo effect, and in particular, his assertion that place of origin is a significant cue confounding one's appreciation of a wine's intrinsic merit. Originality: For the first time, blind and sighted tasting results are collated into one database and statistically interrogated for terroir effects.