Exhibit 23(b) CONSENT OF INDEPENDENT CERTIFIED PUBLIC ACCOUNTANTS We consent to the incorporation by reference in this Registration Statement on Form S-8 (File No. 33-60003) our report dated January 13, 1995 (relating to the financial statements of PV Financial not presented separately herein) appearing in the Westamerica Bancorporation Form 10-K. /s/ Grant Thornton LLP ------------------ Grant Thornton LLP Stockton, California March 21, 1996