In previous work toward speech recognition [M. Akagi, J. Acoust. Soc. Am. Suppl. 1 85, S86 (1989)], a model was developed that predicted target formants in reduced vowels based on the interaction between spectral peak pairs. To substantiate this model, two psychoacoustic experiments were carried out that measured the amount of phoneme boundary shift with (1) a single-formant stimulus as a preceding anchor and (2) a vowel as a preceding anchor. The results of the first experiment were compared with the spectral peak interaction obtained from real speech data using the model. This comparison showed that the perceptual boundary shift with a single-formant anchor is similar to the spectral peak interaction analyzed by the model. Thus the neutralization recovery model is formulated as the sum of the contextual effects resulting from interaction between spectral peaks. Additionally, the comparison of these results with those of the second experiment showed that the phoneme boundary shift with a vowel anchor can be postulated as the sum of the shift with the single-formant anchor and a feedback factor from the perceived preceding anchor.