Phonetic distortions, subtle acoustic traces of how a competitor would be produced on the articulation of a response, have been used as evidence for cascading activation from phonological planning to articulatory implementation, that is that information flows between these levels of representation in the language production system prior to selection at the phonological planning level. Phonetic distortions are a robust finding, when focusing on speech errors, produced either in tongue twisters (Baese-Berk & Goldrick, 2009; Frisch & Wright, 2002; Goldrick, 2016; Goldrick & Blumstein, 2006; Goldrick et al., 2016; Goldstein et al., 2007; McMillan & Corley, 2010; Pouplier, 2007) or in naturalistic speech (Alderete et al., 2021). However, a recent study failed to find evidence for phonetic distortions in another context in which it would be expected, single word reading aloud of irregular words in which the lexical and sublexical routes generate phonological plans for different vowels (Irons, 2020). The goal of this dissertation is to understand why this discrepancy exists, that is why phonetic distortions are observed in some, but not all cases, in which they are predicted by cascading activation theories of speech production as there are many, potentially critical differences between the paradigms that do and do not observe phonetic distortions. In this dissertation, I present two experiments, one using tongue twisters, and one using picture-word interference, designed specifically to control for differences in errors, scope of planning and word position, to allow us to better understand when a cascade from phonological planning to articulatory implementation can be observed phonetically. Similar to past tongue twister work (Baese-Berk & Goldrick, 2009; Frisch & Wright, 2002; Goldrick, 2016; Goldrick & Blumstein, 2006; Goldrick et al., 2016; Goldstein et al., 2007; McMillan & Corley, 2010; Pouplier, 2007) I observed phonetic distortions, evidence for cascading activation in onset tongue twisters. In nucleus tongue twisters I found that cascading activation might present differently in vowels than it does in consonants. We did not, however, observe phonetic distortions in picture-word interference, therefore open questions remain about how scope of planning and error effects may be responsible for phonetic distortion evidence for cascading activation.