“Once you start into the pattern, it becomes a crutch,” Ms. Marshall said. It is not uncommon for people to use filler phrases such as “like,” “so” and “you know,” but it becomes a problem when the phrases are overused to the point of distraction.

She compared it to vulgarity: The occasional use is acceptable but when too frequent, it loses its meaning and signals to listeners that the person speaking is lazy about language.

It also matters when the speech “disfluency” occurs, Ms. Marshall said. If it happens before a thought is expressed, the speaker is more likely to be perceived as lacking confidence or competence, or as being unprepared. It if happens in the middle of a thought, the speaker is judged less harshly.

Speakers who are well known in their professions but overuse verbal pauses are still perceived as credible because they have built a reputation. Audience members will chalk up those habits to just the way they talk, Ms. Marshall said.