Andréia Schmidt

RESPONDING BY EXCLUSION IN WISTAR RATS IN A SIMULTANEOUS VISUAL DISCRIMINATION TASK

Responding by exclusion is to select a correct alternative by rejecting other potential alternatives. Studies describe this ability in some mammals and birds. However, this type of performance has not been reported in rodents. The aim of this study was to verify the occurrence of responding by exclusion in Wistar rats after a baseline of simple simultaneous visual discrimination. Six male Wistar learned nose-poking tunnels displaying visual stimuli (projected geometric shapes) in an operant chamber. After establishing the simultaneous discrimination baseline, three probe sessions were conducted. In each session, there was a novelty-control probe (a new stimulus was presented together with a stimulus trained as the S(+)) and an exclusion probe (a second new stimulus was presented simultaneously with a stimulus trained as the S(-)). Only one rat responded to the new stimulus in one of the three novelty probe trials. Four rats responded to the three new stimuli and one responded to the new stimulus in two of the three exclusion probes. One subject responded to the S(-) in all the exclusion probes. Five of the six subjects were therefore able to choose the new stimulus, rejecting stimuli trained as the S(-). This is the first experimental evidence for performance by exclusion in rats.

Ocorrência de Classes Gramaticais na Fala Espontânea de Crianças de 18 a 41 Meses com Pares

This study aimed to investigate the occurrences of different grammatical categories in 21 children (18 to 41 months) in situations of spontaneous speech with their peers and compare these data with studies that employ the observation of adult/child interaction in the context of elicited speech. Each child was videotaped during 15 minutes interacting with classmates. It happened for five times with intervals of one month between them. Records were joined into four groups. The most frequent grammatical categories in all age groups were verbs and nouns. The frequency of different types of verbs and nouns were equivalent among younger groups, but verbs were more frequently used in older groups. We discuss the role of observation context and the method of data sampling.

Extending Equivalence Classes to Sentences and to Instructional Control

Sidman proposed that the formation of equivalence relations helps to make rule-governed behavior possible. This paper provides some experimental evidence that meaningless auditory and/or pictorial stimuli began to function as instructional stimuli, after their participation in equivalence classes with actions, and actions directed to objects. Without the formation of equivalence classes the participants could not have followed the instructions; however, belonging to a class contributes to, but does not entirely determine that an instruction will be followed. The contribution of these studies is limited to two types of relationships (word x object; word x action) and to the conditions under which they were carried out. Whether the same findings would extend to relations between words and other aspects of the environment, such as qualities, temporal and spatial relations, among others, is a question for future research. Moreover, the experiments employed well-defined categories (names and verbs), but many of these types of words have no “referents”; and sentences are composed of some elements that also have no referents, except their relationship to other elements within the sentence (e.g., the autoclitics). The comprehension of instructions by a listener is a topic that requires further thought and investigation.

Emparelhamento com o modelo simultâneo e atrasado: implicações para a demonstração de equivalência de estímulos por crianças

Delayed matching to sample (DMTS) has been used to teach conditional relations, to test emergent relations between stimuli and to test the maintenance of these performances. The literature, however,