Inner speech is one of the most common, but least investigated, mental activities humans perform. It is an internal copy of one's external voice and so is similar to a well-established component of motor control: corollary discharge. Corollary discharge is a prediction of the sound of one's voice generated by the motor system. This prediction is normally used to filter self-caused sounds from perception, which segregates them from externally caused sounds and prevents the sensory confusion that would otherwise result. The similarity between inner speech and corollary discharge motivates the theory, tested here, that corollary discharge provides the sensory content of inner speech. The results reported here show that inner speech attenuates the impact of external sounds. This attenuation was measured using a context effect (an influence of contextual speech sounds on the perception of subsequent speech sounds), which weakens in the presence of speech imagery that matches the context sound. Results from a control experiment demonstrated this weakening in external speech as well. Such sensory attenuation is a hallmark of corollary discharge.

Talking silently to ourselves occupies much of our mental lives, yet the mechanisms underlying this experience remain unclear. The following experiments provide behavioral evidence that the auditory content of inner speech is provided by corollary discharge. Corollary discharge is the motor system's prediction of the sensory consequences of its actions. This prediction can bias perception of other sensations, pushing percepts to match with prediction. The two experiments below show this bias induced by inner speech, demonstrating that inner speech causes external sounds to be heard as similar to the imagined speech, and that this bias operates on subphonemic content.

Physiology and performance of wild and domestic strains of diploid and triploid rainbow trout 1 (Oncorhynchus mykiss) in response to environmental challenges 2 3 by 4Abstract 11To determine the factors that may contribute to the poor survival of triploid (3n) rainbow trout 12 (Oncorhynchus mykiss) in lake stocking programs, we compared the physiology and responses to 13 environmental challenges of four wild strains and one domestic strain of diploid (2n) and 3n juvenile 14 rainbow trout. Over four successive years, wild trout were caught from nature, spawned and progeny 15 reared in a hatchery along with hatchery-bred domestic trout. Offspring of each strain were raised for 16 up to 12 months as both 2n and 3n and growth rate, critical swimming speed, routine oxygen 17 consumption rate, critical oxygen tensions, thermal tolerance, and hypoxia tolerance were assessed in a 18 laboratory setting. Cohorts of the 2008, 2009, and 2010 wild strains were also stocked into two 19 experimental lakes and recaptured as adults using traps and fyke nets in 2011 for laboratory analysis. In 20 the juvenile trout, the only measure of performance to show a consistent difference between 2n and 3n 21 individuals across all strains was hypoxia tolerance, where 3n trout had a shorter time to loss of 22 equilibrium (LOE) at 16torr than their 2n counterparts, but this effect was not seen in adult lake-reared 23 trout. Strain had a significant effect on specific growth rate, U crit and time to LOE in hypoxia, although 24 the effects of strain on these variables was not consistent from year-to-year. Overall, this study suggests 25 that poorer hypoxia tolerance in 3n trout compared with 2n trout may be a contributing factor to the 26 higher lake stocking mortalities in 3n trout. 27 28 the direction and magnitude of the difference. For example, even for growth rate, some studies show no 48 difference between 2n and 3n fish (O'Flynn et al. 1997) while other studies show that 3n fish grow faster 49 (Galbreath et al. 1994) or slower (McGeachy et al. 1995;McCarthy et al. 1996) than 2n fish. Many other 50 studies have shown minor or inconsistent differences in physiology and stress responses between 2n 51 and 3n fish, and there is little explanation for why 3n fish show higher mortality rates when stocked into 52 potentially stressful natural lake systems. To date, the best possible explanation for why 3n fish may 53show higher mortality rates in natural lakes is due to 3n fish being less tolerant of hypoxia exposure 54 compared with 2n fish (Yamamoto and Iida 1994;Lilyestrom et al. 1999), and hypoxia can be prevalent 55 in lakes due to turnover, eutrophication, and winter ice cover (Diaz and Breitburg 2009). However, 56comparing the effects of triploidy on fish across studies is difficult and confounded by differences in the 57 choice of species, strain, year, and rearing conditions, all of which can have their own effects on 58 physiology and performance (e.g. Guo et al. 1990). 59Numerous studies have shown that strain and population can affe...

The perceptual boundaries between speech sounds are malleable and can shift after repeated exposure to contextual information. This shift is known as recalibration. To date, the known inducers of recalibration are lexical (including phonotactic) information, lip-read information and reading. The experiments reported here are a proof-of-effect demonstration that speech imagery can also induce recalibration.