When President Ronald Reagan told the Soviet Communists to "tear down this wall" in his legendary Berlin speech, it resonated with a lot of people. Reagan was regarded as someone who could do things and listeners reacted accordingly. Some random guy standing on the wall saying the same thing would have had far less impact.

Or take the examples of what students think when a journalism professor who has little experience in journalism critiques their writing. A speaker's power to act on their words influences how a listener perceives the meaning of their message, according to a paper by linguists.

Perception obviously matters. If you are on an airplane and a flight attendant in a uniform asks you to return to your seat, they get a different reaction than if the exact same person using the same voice and words were in plain clothes. 

The linguistic experiment consisted of presenting participants with videotaped statements about politics spoken by a top political decision-maker, a news anchor or an unknown person. In a second scenario, the same people uttered statements related to general world knowledge. Brain responses to implausible statements about current affairs differed when uttered by a political figure as opposed to the other speakers, but implausible general world knowledge statements led to a similar brain response across all three speakers.

Grand average event-related brain potentials (ERPs) timelocked to the critical word (onset at the vertical bar) for general and political statements in Experiment 1 (top panel) and Experiment 2 (bottom panel). For each experiment, the higher panel shows the ERP responses for the high-profile speaker whereas the lower panel shows the ERP responses for the control speaker. ERPs are depicted for two selected electrodes, while the distribution of the N400 and late positivity effects is shown by the topographical maps (false – true). The frame in the top right-hand corner highlights the selective electrophysiological response for false political statements made by the finance minister. Negativity is plotted upwards. Speakers gave written informed consent to the publication of their photos in this figure. Credit and link: 
doi:10.1371/journal.pone.0069173

The effects occur rapidly, they say, within 150-450 milliseconds of hearing a statement, and demonstrate that a listener's response to a message is immediately influenced by the social status of the speaker, and whether he or she has the power to bring about the state of affairs described by their words.

Lead author Ina Bornkessel-Schlesewsky from the Department of Germanic Linguistics at the University of Marburg explains, "Every day, we hear statements that surprise us because they do not correspond to what we (think we) know about the world. Our study demonstrates that, in understanding such utterances, our brain rapidly takes into account who said them (e.g. a politician versus our neighbor) and whether he or she in fact has the power to act upon what was said."

Citation: Bornkessel-Schlesewsky I, Krauspenhaar S, Schlesewsky M (2013) Yes, You Can? A Speaker’s Potency to Act upon His Words Orchestrates Early Neural Responses to Message-Level Meaning. PLoS ONE 8(7): e69173. doi:10.1371/journal.pone.0069173