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| Stimulus Control with Compound Stimuli |
| Monday, August 13, 2007 |
| 10:30 AM–11:50 AM |
| L2 Room 3 |
| Area: EAB; Domain: Experimental Analysis |
| Chair: Paula Debert (University of São Paulo) |
| Discussant: William J. McIlvane (University of Massachusetts Medical School) |
| Abstract: The present symposium presents three stimulus control studies using compound stimuli with human participants, in very different experimental situations. The first study trains simple discriminations between compound stimuli so that different elements may appear together with a common one in S+ compounds (e.g., AB and AC). The study investigates emergent performances in this context, when elements that had accompanied a common one were presented in new compounds (such as BC). The study found emergent performances similar to those found in equivalence studies, suggesting that discrimination with compound stimuli may also give rise to equivalence relations. The second study compared performance of adults with Down’s syndrome and children with typical development, in simultaneous and delayed matching between simple and compound stimuli, and found accurate performance of all participants in simultaneous matching; in delayed matching, however, participants with Down’s syndrome showed poorer performance. The third study used syllables as component stimuli, training children to match two syllable printed words to the corresponding spoken words. Tests investigated control by the syllabic components in probe trials of matching printed words and pictures. The present set of studies show that compound stimuli are powerful tools to investigate several important aspects of stimulus control. |
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| Emergent Conditional Relations in a Go/No-Go Procedure with Stimuli Displayed as Figure-Ground. |
| PAULA DEBERT (University of São Paulo), Edson Huziwara (University of São Paulo), Antonio Moreno (University of São Paulo), Marcelo Silva (University of São Paulo), Robson Faggiani (University of São Paulo) |
| Abstract: Past studies established emergent conditional relations using a go/no-go procedure with compound stimuli with two components displayed side-by-side. During training, each compound stimulus was presented successively at the computer screen for four seconds. Responses emitted in the presence of certain compound stimuli (A1B1, A2B2, A3B3, B1C1, B2C2 and B3C3) were reinforced, whereas responses emitted in the presence of other compounds (A1B2, A1B3, A2B1, A2B3, A3B1, A3B2, B1C2, B1C3, B2C1, B2C3, B3C1 and B3C2) were not reinforced. During tests, new configurations (BA, CB, AC, and CA) were presented, resembling tests usually employed in equivalence studies. The present study evaluated whether conditional emergent performances could be established when components were displayed as figure-ground. This evaluation was conducted with four normal adults. Stimuli were abstract black-and-white figures and colored backgrounds. A computerized program was used to present stimuli and to register subjects’ responses. All participants showed emergent conditional relations during tests. |
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| An Investigation Restricted Stimulus Control in Participants with Down’s Syndrome. |
| CAMILA DOMENICONI (Universidade Federal de São Carlos), Julio C. De Rose (Universidade Federal de São Carlos), Aline Roberta Aceituno Costa (Universidade Federal de São Carlos) |
| Abstract: Participants with mental retardation may respond under control of only part of the stimuli in discrimination tasks, so that they may fail in tests requiring control by several stimulus components. The present study aimed to investigate restricted stimulus control in matching tasks, with simple and compound stimuli (with two components each). It replicated an earlier study by Stromer, McIlvane, Dube, & Mackay (1993), conducted with adults with Down’s syndrome. In the present study, performance of participants with Down’s syndrome was compared with that of children with typical development. Two matching relations were trained with simple samples. Three types of test followed: with compound samples and simple comparison stimuli; with simple samples and compound comparison stimuli; and with compound samples and comparison stimuli. Each test was conducted in simultaneous, 0-delay, and 2-sec delay matching conditions. All participants performed with accuracy above 80% in simultaneous matching tests. In delayed matching tasks, adults with Down’s syndrome performed less accurately than children with typical development. The results confirm the literature indicating that participants with Down’s syndrome did not respond under control of both elements of the samples or comparison stimuli. |
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| Matrix of Performances during Tests of Control by Minimal Units in Reading: Analysis of Multiple Stimulus Classes. |
| MARTHA HÜBNER (University of São Paulo), Mariana Leite (University of São Paulo) |
| Abstract: The process of acquisition of control by minimal units in reading has been shown to be difficult to pre-school children, due to the possibility of the formation of several stimulus classes, some of then incompatible to the stimulus control classes planned in the reading program. The present study had the objective of analyzing 34 performances of pre- school children during tests of control by minimal units in reading. Participants were nonreading children, four to five years old. A computerized teaching program was conducted. It involved the acquisition of reading through the stimulus equivalence paradigm (training children to match pictures to spoken words and printed to spoken words) and tests of control by minimal units in probe trials of matching between pictures and printed words. Performance was analyzed through a matrix of responses, where one can identify, for each sample, the frequency of responses to each comparison stimulus. A frequent result was that in the beginning of the acquisition of control by minimal units each word can control behavior as a compound stimulus and its components can be seen as part of the same class. According to this, the words CABO and BOCA, for example, are chosen as equivalent. Special procedures were necessary to break these classes. |
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