Data from perceptual tests in which subjects were asked to identify tense and lax vowels are used to suggest correlates for the tense/lax distinction in general American English. Four vowel parameters were manipulated in synthetic nonsense words of the form [dVs]: formant frequency, duration, breathiness, and first‐formant bandwidth. The tense/lax pairs included [ɪ], [æɛ], [uᴜ], and [ɑʌ]. Three separate identification tests are created in which the stimuli vary only in formant frequency and one of the other three parameters. Each test was presented to five naive native speakers of general American English. Results so far indicate that shortening the vowel shifts judgments toward the lax vowel, and that this effect is greater in the low vowel pairs than in the high vowel pairs. Increased breathiness shifts judgments toward the tense vowel for high vowels. The effect of breathiness on low vowels and the effect of bandwidth of the first formant on all vowels is as yet unclear. [Supported in part by NINCDS and a NSF Fellowship.]