Six experiments were run to determine whether the duration of conditioned defensive burying (COB) in rats is a function of its consequences. Four experiments developed the methodology. Experiment 1 replicated the standard one-trial experiment, where rats are shocked once by a prod. All three rats exhibited CDB. Experiment 2 used a lever-press-for-water contingency to force recontact with the lever, following shock deliveries in Sessions 6 and 14. All three rats buried the lever in both sessions. Experiment 3 replicated Experiment 2, employing albino and hooded rats. All six buried the lever. The albinos exhibited longer burying durations. Experiment 4 used the lever-press-for-water contingency but employed extinction to test whether rats would bury the lever under that condition. They did not. Experiment 5 used three groups of rats to determine whether burying durations are a function of CDB's consequences. Groups LS and LSH had enough sawdust to cover the lever, but a hole under the lever was opened during LSH's burying. Group SS lacked enough sawdust to cover the lever. The groups' mean burying durations (MBDs) were not significantly different in Session 6. Following Session 14, group differences and a group-by-session interaction were statistically significant. Effect sizes for Groups LS and SS were large. Group LS's MBD increased, Group LSH's remained unchanged, and Group SS's decreased. Experiment 6 used two groups of rats to determine whether MBDs are a function of shock source visibility. Group C's substratum consisted of uncolored, transparent Plexiglas blocks. Group B had black, opaque blocks. Only the group-by-session interaction was statistically significant. The MBDs of Groups Band C paralleled those of Groups LS and SS in Experiment 5. The effect sizes for C and B were large and medium, respectively. CDB occurred in all experiments where the rats received shocks, and CDB was reproduced in experiments where the animals were forced to recontact the shock source through a lever-press-for-water contingency. CDB durations are a function of their consequences. Rats whose burying covers or blocks the shock source from view exhibit longer burying durations in succeeding shock trials. Rats whose burying is ineffective exhibit shorter durations.

abstract: Languages have long been studied through the rhythm class framework, which discriminates them into separate classes on the basis of shared rhythmic properties. Originally these differences were attributed to the isochronous timing of different prosodic units, such as stress intervals in “stress-timed” languages and syllables in “syllable-timed” languages. More recent work has turned to durational metrics as a means of evaluating rhythm class, by measuring the variability and proportion of segmental intervals in the speech stream. Both isochrony and durational metrics are no longer viewed as correlative with natural language rhythm, but durational metrics in particular have remained prevalent in the literature. So long as the conclusions of durational metrics are not overextended, their analysis can provide a useful mechanism for assessing the compatibility of a language with a given rhythm class by way of comparative analysis. This study therefore presents a durational-metric comparison of Scottish Gaelic, a language which has frequently been described as stress-timed but has never been empirically tested for rhythm class, with English, a prototypical and well-studied example of a stress-timed language. The Gaelic metric scores for %V (percentage of vocalic content), ΔV (standard deviation in vocalic interval length), and ΔC (standard deviation in consonantal interval length) (Ramus et al. 1999) are shown to be very similar to those measured for English, indicating that the language displays similar patterns of durational variability and segmental proportion typically ascribed to a rhythmically stress-timed language. This provides clear support for the classification of Scottish Gaelic as stress-timed. / Dissertation/Thesis / Masters Thesis Linguistics and Applied Linguistics 2020

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This cumulative dissertation investigates features of sociolinguistic variation in spoken English by non-native humans and agents. It presents a thorough summary and systematization of previous research on Chinese English, a quantitative analysis of the Chinese English vowel spaces of speakers from Guangdong, Guangxi and Yunnan, a quantitative analysis of durational variation of speakers from different inner, outer, and expanding circle varieties of English, and a study of sociophonetic variation by a pedagogical agent. Furthermore, the thesis proposes a linguistically based quality metric for text-to-speech systems.