Final answer:
The use of disclaimers is a speech pattern that decreases a speaker's perceived assertiveness, as it can suggest uncertainty and lessen confidence in the speaker's statements.
Step-by-step explanation:
According to communication experts, the type of speech pattern that decreases a speaker's perceived assertiveness is the use of disclaimers. Disclaimers are phrases that can soften the tone of the message and imply uncertainty, such as “it seems that,” “it appears to me that,” or “I may be wrong, but.” Although this can invite the listener into a constructive conversation and represent uncertainty fairly, it can also undercut the speaker's assertiveness and make them appear less confident in their statements.
This contrasts with speech patterns that might amplify assertiveness, like clear enunciation and the use of specific jargon. Too much informality, inappropriate transitions, or an illogical sequence of information can further diminish a speaker's effectiveness and perception of assertiveness.