ROBERT YODER'S long been a favorite of mine for the deft way he works with language and symbol in his collages. In his current show at Howard House, he's taken his game to a new level. What Yoder does, basically, is collect signs -- road signs, painted grocery store placards, printed paper bags -- and cuts them up. He then carefully reassembles them, removing the meaning of their words and letters, leaving only symbols and the tension between the signs' apparent desires to communicate something and our desire to understand what they're trying to communicate. Roman letters are transformed into unreadable symbols, as if he's discovering as of yet uninvented letters. What always remains is the draw of the symbol and of the sign, a kind of totemistic power that apparently exists even in the absence of language.

In past showings, Yoder has refined his virtuosic alterations of symbols; in this show, he has in many ways moved on. A few small wooden sign collages and a four-piece series for which he reassembled grocery store logos from brown paper bags remain to display his skill at the craft. Three, titled Colas Breugnon I, II, and III (Yoder's titles are good at conveying the mixture of nonsense and meaning that is universal in his work) are taken from the same place, a grocery store in Eugene, Oregon. Yoder has transformed the italic lettering used by the store into a sort of Arabic script, a line with curving characters attached to it. In a fourth, smaller piece based on a different store's paper bag, a single red character, midway between English cursive and the Egyptian hieroglyphic eye, spins graceful red lines in a tight composition.

But the real story is a trio of larger pieces that show a shift in Yoder's approach to his chosen materials. One of the best pieces doesn't even use letters. In Candyland, Yoder works with the iconic diagonal orange-and-white striped boards from roadway safety barriers (you know, those sawhorse-like objects). Obviously, the orange stripe is a common symbol that communicates clearly to at least all Americans, but Yoder's shifted here from letters to nonlinguistic symbols. The stripe means something very specific, outside of language; "caution" or similar words can't contain its meaning.

Yoder organized the boards into a flat square, and the stripes are aligned so they create continuous diagonals, bend at 90 degree angles, or in a few cases, miss their connections, creating little jags in the composition. The stripes are arranged so as to lead your eye around the picture, but then to frustrate your eye's progress. The composition never resolves into a clear form, though it hints at a spiral structure. Instead, the surface practically vibrates under the tension between its harmonies and dissonances. In this way, the piece effortlessly integrates the "allover" composition of a Jackson Pollock painting with the hard-edge forms of the color-field painters who followed him.

In another nice touch, Yoder's scavenging has turned up at least three different varieties of the striped boards: Though the tone of the orange stripes is constant, some are loosely painted, with visible brushstrokes; others are perfectly smooth in finish, and a third type is done with the kind of paint that has near-microscopic glass beads mixed in to make it highly light-reflective for highway use. So the closer you get to the surface, the more detail there is to observe.

The title of Stateroad continues the sense that Yoder is working with a subject outside of language, in this case moving nearer to landscape painting than the printed word. The landscape in question, of course, is the road, where uncountable signs vie for your attention, as if you were walking down the aisle of a supermarket. No Parking. Speed Limit 55. Exit 37. Gas, Food, Lodging. In Stateroad, Yoder has cut the signs down to near uniform planks, 14 inches long, then connected them with a pair of chains. They hang from the top of the gallery straight down to the floor, then gather in a big roll on the floor. The piece is 30 feet long, all told, and most of it is in that roll. The signs are more legible than usual; the confusion stems not from their unreadability but from their profusion, their messages competing with and contradicting each other.

Wellsme, a massive, near-circular floor piece that is eight and a half feet in diameter, boasts a similarly confused stew of meaning. In these two pieces, Yoder works with the signs themselves, rather than solely with their linguistic elements. The result feels like, well, a picture of America.