Watch Art Cashin: The next market mover

Cashin says stocks are checking their vital signs

Art Cashin said stocks are "trying to check their own vital signs" as the market awaits Federal Reserve chair Janet Yellen's next appearance before Congress, scheduled for Thursday.

Cashin, UBS' director of floor operations at the NYSE, told CNBC's Bob Pisani around midday he expects Yellen will get sharper questions than she did two weeks ago. Since then we have "both new economic data and the transcripts from 2008."

He thinks Yellen will be pressed because "it would appear the Fed wasn't fully aware of the circumstances then." As a result, she will get questions like, "Madame Chairman, how aware are you people now of what is really going on? What's the difference between your perception and reality? It could be somewhat sharper questioning."

Cashin said the uncertainty revealed by the transcripts should "serve to remind the viewers and all the rest of us that the Fed has somewhat of a checkered past, especially when it comes to forecasts."