JOURNAL OF THE EXPERIMENTAL ANALYSIS OF BEHAVIOR
1977, 27, 381-392
NUMBER
2 (MARCH)
EXTENDING SEQUENCE-CLASS MEMBERSHIP WITH MATCHING TO SAMPLE' RONALD LAZAR NORTHEASTERN UNIVERSITY Three normal adults were first trained to point sequentially to each member of several pairs of visual stimuli. This baseline training established one class of stimuli to which subjects responded first, and another class of stimuli to which they responded second. Then, in a matching-to-sample procedure, baseline-sequence stimuli served as samples and new visual stimuli served as comparisons. Subjects were trained to choose one group of new comparisons when the sample was a "first" stimulus from the sequence baseline, and to choose the other new comparison stimuli when the sample was a "second" from the sequence baseline. When the new stimuli were then presented as pairs in the posttest, two subjects pointed to them in sequences predictable on the basis of the stimulus-class membership established during matching to sample. The failure of one subject to demonstrate sequential transfer was shown to be a consequence of the failure of the matching-to-sample procedure to establish stimulus classes. The production of sequences that were not directly trained suggested an empirical approach to the analysis of simple grammatical behavior. Key words: stimulus equivalence, matching to sample, generative behavior, normal adults
By manipulating reinforcement contingen- standard "mediated-transfer" experiment, in cies in the presence of specified aspects of the which paired-associate techniques are used (cf. environment, one can establish an arbitrary Jenkins, 1963), two verbal elements, B and C, relation between a given response and two or become associated because both are associated more stimuli. Such stimuli have been defined with a third element, A. More recently, matching-to-sample proceas functionally equivalent (Goldiamond, 1962). A young child, for example, might be trained dures have been used to produce stimulus to say "car" when shown a picture of a car, and equivalences. For example, after learning to "hat" when presented with a picture of a hat. match pictures and printed words to correWith further training, the child might also sponding dictated names, retarded subjects be taught to say "car" and "hat" when pre- could then match the printed words with the sented with the corresponding printed words. pictures without additional training (Sidman, Since members of a given picture/printed- 1971; Sidman and Cresson, 1973). The logic of word pair can function interchangeably as oc- these experiments is similar to the paired-ascasioners for the same response ("car" or sociate paradigm. Subjects first learned to "hat"), the picture and printed word represent match B (pictures) to A (dictated words), and a class of functionally equivalent stimuli. C (printed words) to A (dictated words); they Evidence from the laboratory has indicated, were then able to match B to C, and C to B. however, that stimuli can become functionally Since printed words and pictures could be inequivalent even if one does not directly train terchanged with corresponding dictated-words, the same response to each stimulus. In the each picture/printed-word/dictated-word triad represented a class of equivalent stimuli. The development of stimulus equivalences in 'This study was supported by Grant HD 07075 from the National Institute of Child Health and Human matching to sample has been demonstrated Development. Some of these data were presented at the also with other severely retarded adolescents Eastern Psychological Association meeting, New York, (Mackay, in press; Sidman, Cresson, and Will1976. The author is indebted to Murray Sidman for his son-Morris, 1974), younger retarded children advice and guidance during the research. Reprints may (Spradlin, Cotter, and Baxley, 1973), global be obtained from the author, Center for Personalized Instruction, Georgetown University, Washington, D.C. aphasics (Glass, Gazzaniga, and Premack, 1973), and chimpanzees (Premack, 1971). 20057. 381
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Although matching to sample can establish language. They were then trained to do the functional equivalences between correspond- same with stimuli Bl and B2 (first touch Bi, ing samples and comparisons within the con- and then touch B2). After this baseline was text of the matching paradigm, such acquired learned, trials with stimulus pairs Al and B2, equivalences may extend also to stimulus func- Bl and A2 were given (Phase II) to determine tions established in other contexts. Suppose, whether sequential pointing behavior was confor example, that stimulus A was a member of trolled by one class of stimuli to which subclass X, as defined by some function outside of jects responded first, and by another class to matching to sample. If stimulus B were then which they responded second. If such classes made equivalent to A via matching to sam- had formed, they were expected to touch Al ple, would B also become a member of class first and then B2, or Bl first and then A2. Subjects were then pretested (Phase III) with X? The matching-to-sample procedure would become of greater importance if it could pro- new pairs of visual stimuli, for example El vide a means by which stimuli gain member- and E2, to ensure that there were no consistent ship in classes established outside the match- patterns of sequential responding to these new stimuli before they were used in Phase IV. ing paradigm. The first part of Phase IV consisted of a The general plan of the experiment was the following: a sequential-response training pro- matching-to-sample procedure in which the cedure was to establish two stimulus classes; baseline stimuli, Al and A2, were presented for purposes of exposition, one class will be as samples and the new stimuli, El and E2, called "first" and the other "second'.'. Then, were comparisons. Plus signs indicate the corby means of a matching-to-sample procedure, sample-comparison equivalences were to be tHASE l: BASELINE-SEQUENCE A1-A2 A2- 1 established; the comparisons were new stimTRAINING S1--S2, B2--B not used in but the the sequence training, uli, samples were members of the sequence classes "first" and "second". Finally, the comparison PHASEI1: TEST FOR
[email protected] B24.---A1 SEQUENCE CLASSES stimuli were to be tested for appropriate memBi--- A2, 2--B bership in the sequence classes. Would stimuli that had become equivalent in the context of IIU: SEQUENCE PRETEST matching to sample also share membership PA .1....'E2 , E24....E (NEW STIMULI) in the independently established sequence classes? PHASEIV: ,
MATCHING-TOSAMPLE TRAINING
METHOD
Subjects Three normal adults, two females, ages 21 and 47 yr, and one male, age 23, had no previous experimental experience nor had they taken any courses in psychology. General Experimental Design The experiment was designed in a series of steps, each of which was a prerequisite to the next. The following outline represents a few procedural examples from each phase. Subjects were presented two visual stimuli, designated Al and A2 in Figure 1, Phase 1, and were taught to point first to Al and then to A2, regardless of spatial position. (The actual stimuli used in the experiment are described below.) Arbitrary stimuli were used to reduce influences from the subjects' natural
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E. ...... E2 , E24.-.- El (NEW STIMULI) Fig. 1. Outline of experimental procedures. Each phase shows two stimulus configurations. Sequential pointing responses were required in Phases I, II, III, and V; arrows indicate the order in which subjects were expected to respond. In matching to sample, Phase IV, subjects pointed to one of two lower (comparison) stimuli; plus signs indicate the correct choices. The upper-case letters shown here were not the actual stimuli presented to the subjects.
GENERATING SEQUENTIAL BEHAVIOR rect comparison in each stimulus configuration: the subjects were taught to point to El when Al was the sample and to E2 when A2 was the sample. If subjects learned during the initial matching-to-sample training that El was functionally equivalent to Al and thereby to "first", and that E2 was functionally equivalent to A2 and thereby to "second", then they should without further training be able to match El to Bl ("first") and E2 to B2 ("second"). This was tested as part of Phase IV. If subjects could not do this latter task, they were taught it. After having been taught the matching-tosample tasks, they were again tested for sequential responding to the stimulus pair El and E2 (Phase V). If the matching-to-sample training had transferred "first" and "second" class membership to these stimuli, the subjects should, without further training, point to stimulus El first and to stimulus E2 second. Apparatus and Materials Subjects sat at a table on which were placed a translucent window in a black frame, and a wooden board with picture hooks. The window (Figure 2A) was used to display response cards on all trials, and the board (Figure 2B) was used to display cue cards during training trials only. The window, 15.2 by 8.9 cm, was mounted on a black base, 15.2 by 10.2 by 1.7 cm, and was parallel to the table top. Stimulus-response cards were inserted manualIy into a 0.16-cm slot between the window and its base. The board, 26 by 53.3 cm, was located 30.5 cm behind the window and tilted 700 with respect to the table top. Eight picture hooks, used to display cue cards during teaching, were placed in rows of two and columns of four. The top row was 2.5 cm below the top of the board, and the two columns were 0.7 cm from each side. There were 16.5 cm between hooks in each row and 12.7 cm between hooks in each column. Stimuli were drawn in black ink on 10.2 by 15.2 cm white cards. A stimulus consisted of two horizontally adjacent isosceles triangles. Each triangle was 0.95 cm in base length and height, and there were 1.3 cm between the midpoints of triangles within a single stimulus. Sequence cards (Figure 3A) displayed two stimuli (pairs of triangles) that were 8.2 cm
383
A
Fig. 2. A schematic view of the apparatus: (A) the Plexiglas window under which response cards were presented; (B) the board that displayed cue cards during training.
apart, 4.4 cm below the top of the card, and 2.5 cm from each side. Matching cards (Figure 3B) displayed three stimuli. One stimulus, the sample, was located midway between the two sides and 6.7 cm below the top. The remaining two stimuli, the comparisons, were 8.2 cm apart, 1.7 cm above the bottom of the card, and 2.5 cm from each side. The actual stimuli used in each phase are described below in conjunction with the relevant procedures. Cue cards were hung on the display board to facilitate the initial teaching of each sequence and matching-to-sample task. There
A. B. Fig. 3. (A) a sequence card; (B) a matching-to-sample card.
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were three general classes of cue cards. One class exactly resembled sequence or matching cards except for the presence of a small arrow (1.3 by 1 cm). On a sequence-cue card, a black arrow pointed from the stimulus the subject was to touch first toward the stimulus to be touched second. On matching-cue cards, a red arrow pointed from the sample to the correct one of the two comparison stimuli. The second group of cue cards exactly resembled sequence and matching stimulus-response cards (no arrow), while the last class consisted of blank cards. Subjects could view the cue cards hung on the board, but they responded to the stimulus cards located in the window. The left-right position of sequence and comparison stimuli on response cards was systematically varied. Chimes rang after correct responses, and a buzzer sounded after incorrect responses. Neither chimes nor buzzer sounded after probe trials (described below). Subjects received a base fee of $1.50 for each experimental session plus $0.01 for each correct response. Money earned by a subject (ranging from $2.50 to $4.00) was paid after each session had ended. The experimenter, who sat at the subject's right, presented stimulus cards, activated the chimes or buzzer, and recorded all data. PHASE I. BASELINE-SEQUENCE TRAINING Procedure The subjects were taught the sequence baseline shown in the upper portion of Figure 4. Stimuli were differentiated by the orientation of each of the two triangles in one of four directions: apex above, below, to the left, or to the right of the base. Subjects were taught four baseline sequences so that each triangle would appear once per card and would occupy each of the four possible positions. For purposes of description, each set of stimuli is designated by a letter of the alphabet, and stimuli within a set are designated by the corresponding letter and a subscript 1 or 2. The subscript indicates the order in which that stimulus was to be chosen. A procedure designed to minimize errors was used to teach each subject the appropriate sequences. A trial consisted of the presentation of a response card, the subject's pointing behavior, and removal of the card. There was no time limit for a trial. On the first trial in Session 1, subjects were presented a sequence-
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