Hybrid turn restriction signs : comprehension of some alternative forms.

TWO EXPERIMENTS WERE CARRIED OUT TO INVESTIGATE THE ACCURACY OF INITIAL COMPREHENSION OF SOME ALTERNATIVE FORMS OF HYBRID TURN RESTRICTION SIGNS. A HYBRID SIGN IS ONE IN WHICH THE MESSAGE IS PRESENTED IN BOTH SYMBOLIC AND VERBAL FORM. IN THE FIRST EXPERIMENT IT WAS FOUND THAT: (1) HYBRID SIGNS WERE BETTER UNDERSTOOD THAN SEMI-HYBRIDS; (2) HYBRIDS WITH A PROHIBITORY VERBAL COMPONENT WERE BETTER UNDERSTOOD THAN THOSE WITH A MANDATORY VERBAL COMPONENT; (3) BEST OF THOSE TESTED WERE HYBRIDS WITH BOTH SYMBOL AND WORDS IN PROHIBITORY FORM. IN VIEW OF THE KNOWN ADVANTAGES OF MANDATORY SIGN FORMS IN TERMS OF MOST OTHER CRITERIA OF SIGN EFFECTIVENESS, A SECOND EXPERIMENT WAS CARRIED OUT TO INVESTIGATE INITIAL COMPREHENSION OF SIGNS DISPLAYING COMBINATION (MANDATORY PLUS PROHIBITORY) SYMBOLS. IT WAS FOUND THAT SUCH SYMBOLS WERE BETTER UNDERSTOOD THAN BOTH MANDATORY AND PROHIBITORY SYMBOLS. COMPREHENSION OF HYBRID SIGNS CONSISTING OF A COMBINATION SYMBOL AND A PROHIBITORY VERBAL COMPONENT WAS AS GOOD AS THAT OF COMPLETELY PROHIBITORY HYBRIDS, AND THEIR USE IS THEREFORE RECOMMENDED (A). THE NUMBER OF THE COVERING ABSTRACT OF THE CONFERENCE IS IRRD NO 255423.