Style tip on punctuating parenthetical material

You have various options to punctuate interruptions of a sentence. You can set off an interruption with commas, parentheses, or dashes.

Example sentence: Psychologists recognize that slight changes in appearance, a reddening of the face or neck and a bit of perspiration on the brow, often suggest that a client is lying about personal motives.

Example sentence: Psychologists recognize that slight changes in appearance (a reddening of the face or neck and a bit of perspiration on the brow) often suggest that a client is lying about personal motives.

Example sentence: Psychologists recognize that slight changes in appearance – a reddening of the face or neck and a bit of perspiration on the brow – often suggest that a client is lying about personal motives.

The parentheses and dashes are a more noticeable marking of the interruption than commas, giving the reader more of a signal.

Another option, perhaps preferable, is not to interrupt the main clause, but to move the interruption to the end of the sentence.

Example sentence: Psychologists recognize that slight changes in appearance suggest that a client is lying about personal motives: some reddening of the face or neck and a bit of perspiration on the brow.

Example sentence: Psychologists recognize that slight changes in appearance suggest that a client is lying about personal motives (some reddening of the face or neck and a bit of perspiration on the brow).

Example sentence: Psychologists recognize that slight changes in appearance suggest that a client is lying about personal motives -- some reddening of the face or neck and a bit of perspiration on the brow.