Distinguishing underlying and surface variation patterns in speech perception

Abstract

This study examines the relationship between patterns of variation and speech perception using two English prefixes: 'in-'/'im-' and 'un-'. In natural speech, 'in-' varies due to an underlying process of phonological assimilation, while 'un-' shows a pattern of surface variation, assimilating before labial stems. In a go/no-go lexical decision experiment, subjects were presented a set of 'mispronounced' stimuli in which the prefix nasal was altered (replacing [n] with [m], or vice versa), in addition to real words with unaltered prefixes. No significant differences between prefixes were found in responses to unaltered words. In mispronounced items, responses to 'un-' forms were faster and more accurate than to 'in-' forms, although a significant interaction mitigated this effect in labial contexts. These results suggest the regularity of variation patterns has consequences for the lexical specification of words, and argues against radical under-specification accounts which argue for a maximally sparse lexicon.

Keywords: Speech perception; lexical access; phonology; speech variation; underspecification.

Figure 1:

Word Response Group: mean response latency for words (hits) and modified words (false alarms), broken out by prefix and stem. There is no significant difference in responses to words. In modified words, labial stems have shorter response times than dorsal stems in both prefix sets (p = .03).

Figure 2:

Modified Word Response Group: mean response latency for modified words (hits) and words (false alarms), broken out by prefix and stem. There is no significant difference in responses to words. In modified words, labial stems have shorter response times than coronal stems (p = .003) and dorsal stems (p = .04) in both prefix sets. Responses to ‘un-’ items are faster than ‘in-’ items (p = .0006).

Figure 3:

Word Response Group: mean accuracy for words and modified words, broken out by prefix and stem. There is no significant difference in responses to words. In modified words, responses to ‘un-’ stimuli were more accurate than responses to ‘in-’ stimuli (p = .01). Responses to labial stems were less accurate than coronal stems (p = .003) and dorsal stems (p = .02) in both prefix sets.

Figure 4:

Modified Word Response Group: mean accuracy for words and modified words, broken out by prefix and stem. There is no significant difference in responses to words. In modified words, responses to ‘un-’ stimuli were more accurate than responses to ‘in-’ stimuli (p = .0001). For ‘un-’, responses to labial stems were less accurate than coronal stems (p = .001).