This invention relates to assays which screen for compounds that modulate taste elicited by the T1R2/T1R3 sweet taste receptor which include a novel counter screen to eliminate false positives. In addition, the invention contemplates assays which screen for compounds that modulate taste elicited by the T1R1/T1R3 umami taste receptor which include a novel counter screen to eliminate false positives. Preferably the assays are conducted in high throughput format thereby enabling the screening of many hundreds of different compounds whereby the counter screen significantly improves assay efficiency. Further, the invention relates to the use of the compounds identified in the subject screening assays to modulate T1R associated taste perception.