The relationship between experimental method and the perception hypothesis being examined is a particularly critical one. Here, earlier studies employing the click-placement method are surveyed, and the conclusions drawn there about the perceptual processes involved are discussed. A working hypothesis is developed which enables an examination, for the first time, of Ladefoged and Broadbent’s [1960] original claim concerning basic processing units. Within a hypothetical framework of hierarchically organized perceptual decisions, the click-placement task is applied in a series of experiments designed to approach the question of processing units at segment, syllable and foot level. Evidence is found for the psychological reality of the syllable and foot. The phonetic basis of the foot is examined and found to be replaceable by top-down information. Between foot and syllable level, indications of differential word demarcation were found, dependent on differences in segmental structur