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Data on 1562 methadone maintenance patients (experimentals) in New York State were gathered through face-to-face interviews. A control group of 1059 people was constructed by asking the experimentals to volunteer names of non-addicted friends. State driver records for 718 experimentals and 579 controls were obtained and analyzed. In general, experimental subjects were no worse drivers than the controls either as patients or while they were using heroin. This was so despite the fact that the experimentals estimated their mileage to be at or above the national average throughout their abuse of non-narcotic and narcotic drugs and during their methadone treatment. It was also found that drug abusers who drive are likely to drive immediately after using drugs. There was an indication that narcotic users are able to compensate for drug effects.

Each trial consisted of dichotomous (high and low frequency) tones started in a random sequence which changed to a patterned sequence. S pressed a switch when he recognized that the sequence was patterned and pressed it again when he could describe the pattern. Rate of presentation was varied. Descriptions were verbalized or tapped. The data showed that descriptions were begun with the longest run of identical tones at the slow rate (1 tone/sec) and ended with the longest run at the fast rate (4 tones/sec). This effect was greater with verbalized than with tapped descriptions. At the medium rate (2 tones/sec), descriptions began with the longest run for patterns of nine tones or more and ended with the longest run for patterns of eight tones or less. Pattern recognition occurred substantially sooner than pattern description. The difference in time between these two responses remained constant across rate, while the difference in number of tones increased with rate. The results are discussed in terms of mode of processing, level of processing, and short-term storage.

Ss listened to and then described continually repeating sequences of nine tones presented at the rate of three tones/second. Each tone was either 275 Hz (high) or 250 Hz (low). The major independent variable was starting pattern (where E began the continually repeating sequence). The major dependent variable was S’s description. The results showed that the “better” the starting pattern, the more often it was accepted and used as the description. “Better” starting patterns were also learned more quickly.

Subjects observed and then described continuously repeated twoelement temporal patterns (one of two alternative elements per event) and their component one-element patterns (one element or its nonoccurrence per event). Descriptions could begin at any event in a pattern, since there are as many possible descriptions as events in continuous patterns. Descriptions of one-element patterns revealed two organizing principles: preference for longest gap at the end, or longest run of positive events at the beginning. Variability of pattern organization was low when in a particular pattern these two principles were compatible or when the principles were incompatible but with the gap principle stronger, and increased when the two principles were incompatible and equally strong or the run principle was stronger. The descriptions of two-element patterns showed that one element emerged as 'figure' and the organizing principles for that element determined the perceived organization for the two-element pattern. It was concluded that variability and difficulty of two-element perceptual organization is a function both of figure-ground relations between the two elements and of compatibility of one-element organizing principles. A temporal pattern is a continuously repeating sequence of events. In a two-element pattern a single event is the occurrence of one of two alternative elements in a given unit of time. In a one-element pattern, an event consists of the occurrence or nonoccurrence of a single element. A two-element pattern may be thought of as the interlocking of two one-element patterns, since any two-element pattern can be decomposed into two unique one-element patterns. To illustrate, the two-element pattern XXXOXOO . . . contains XXX'X" ... and "'O'OO .. . as its unique one-element patterns, with the (') indicating the nonoccurrence of an element in the given unit of time. There are as many different possible organizations for a temporal pattern as there are events in the pattern. For example, the twoelement pattern XXO . . . can be organized XXO, XOX, or OXX. Each of these organizations, when repeated continuously, produces patterns which are indistinguishable from each other except in terms Received for publication November 17, 1969. This study was supported by Grant MH-14229 from the National Institute of Mental Health to Yale University. The authors are indebted to Mr. Nigel Cox for help in instrumentation.