Equivalence class analysis of responding consistent with the relational frame of opposition.

We replicated and extended studies showing that contextual cues for matching stimuli from 2 separate equivalence classes control the same derived relations as contextual cues for opposition frames in RFT studies. We conducted 2 experiments with 6 college students. In Phase 1, they received training in a conditional discrimination AB. Then, they received training for maintaining AB with X1 as context, and for reversing the sample-comparison relations of AB, with X2. In Phase 2, X1 functioned as context for matching same-class stimuli, and X2 functioned as context for matching separate-class stimuli. In Phase 3, X2 controlled the same derived arbitrary relations as cues for opposition frames in RFT studies. This functional equivalence may suggest that X2 functioned as a cue for opposition frames. In Phase 4, participants matched different stimuli with X2 as context, instead of matching most different (opposite) stimuli. In addition, Different, a cue for matching different stimuli, controlled the same derived arbitrary relations as X2. These results are incompatible with X2 being a cue for opposition frames. Contextual control over equivalence and responding by exclusion can explain these outcomes. The implications of these findings for RFT studies on opposition frames are discussed.

A descriptive analysis of baseline and equivalence-class performances under many-to-one and one-to-many structures.

The purpose of the present experiment was to describe responding as a function of One-to-Many (OTM) and Many-to-One (MTO) training structures and identify baseline performances correlated with the accuracy level in tests for equivalence class formation. Participants were 42 adults assigned to either the MTO or the OTM groups, trained on 24 baseline relations, and assessed on the emergence of three 9-member equivalence classes. Participants in the MTO group presented similar frequencies of responses to each of the comparisons throughout baseline training. Also, the number of trials required to meet the baseline mastery criterion was negatively correlated with test accuracy. Participants in the OTM group presented more variable frequencies of responses to each of the comparisons (participants tended to select some of the comparisons less often than others at the beginning of the training). In addition, the number of reinforced responses to the node presented as a sample during training was positively correlated with the number of correct responses during testing for the OTM group. The experiment contributed to an in-depth stimulus control analysis of baseline and test performances, and its results have implications for understanding potential sources of variability between the training structures.

Equivalence class formation when responding is separated from sample and comparison stimuli: Working memory, priming, and sorting.

The experiment determined whether equivalence class formation required overlap of comparison stimuli and responding. Each trial contained a sample first, a single, nonoverlapping comparison second, and a nonoverlapping response-window (RW) third, during which the participant made one of two responses (2R). All 11 participants formed two 3-member ABC equivalence classes using these "trace-stimulus-pairing two-response with response window" (TSP-2R-RW) trials. After adding a fourth stimulus (D) by CD training, ABCD tests showed immediate expansion to 4-member ABCD classes. When 4-member probes (AD, DA, BD, DB, CD, DC) were administered without 3-member probes, many participants showed decrements in class-indicative responding that then resurged to mastery with test repetition. Thus, 3-member probes enhanced class expansion. Class formation occurred for all participants when responding was temporally dissociated from the comparisons. In a matched, contemporaneously published experiment, where responding occurred during comparisons, only 54% of participants formed the classes. Thus, the comparison-response-separation nearly doubled class formation. Additionally, a special post-class-formation sorting test documented the emergence of two explicit equivalence classes. Finally, we noted a 1:1 correspondence for TSP-2R-RW and priming trials. Since priming measures neural substrates of equivalence classes, TSP-2R-RW trials should do the same.

Simple discrimination training with differential responses to establish functional and equivalence classes with preschool children.

The present study assessed whether simple discrimination training with differential responses would produce functional and equivalence classes with preschool children. In Experiment 1, we exposed 10 children to simple successive discrimination training in which they had to press different buttons (selection-based responses). Response 1 (R1) was reinforced only in the presence of A1, B1, or C1, and Response 2 (R2) was reinforced only in the presence of A2, B2, or C2. We assessed the formation of functional classes by training new selection responses in the presence of one member of each class (A1-R3, A2-R4) and testing to see if these responses would occur in the presence of other members. Eight children responded consistently with functional class formation. Four of these eight children also responded consistently with the formation of equivalence classes. Experiment 2 investigated whether differential motor responses (i.e., gestures) would improve equivalence class yields. Three of six children showed both functional and equivalence class formation. In general, the results indicate that the simple discrimination procedure with differential responses yielded functional and equivalence class formation.

Funções de Estímulos Pré-experimentais na Formação de Classes de Equivalência / Pre-experimental Stimuli Functions in Equivalence Class Formation

Resumo Relações condicionais pré-experimentais que eliciam respostas emocionais, como ciúme, podem afetar a formação de classes de equivalência? Haveria diferenças entre homens e mulheres? Para abordar essas questões, 19 participantes, de ambos os sexos, foram expostos a treinos e testes para a formação de quatro classes de equivalência, uma delas constituída pelo nome do(a) namorado(a), o nome de mulher/homem desconhecida(o) e duas figuras não-familiares. Após os testes, aplicou-se a Escala de Ciúme Romântico. Os participantes classificados com maior grau de ciúme não formaram as classes de equivalência, independentemente de serem homens ou mulheres. Sugere-se que relações pré-experimentais com funções afetivas interferiram na formação das classes de equivalência em que o nome do namorado(a) deveria ser relacionado ao nome de desconhecido(a).

Abstract Can pre-experimental conditional relations that elicit emotional responses, such as jealousy, affect the formation of equivalence classes? Would there be differences between men and women? To address these questions, 19 participants of both sexes were exposed to training and testing of the formation of four equivalence classes, one consisting of the boyfriend's/girlfriend's name, an unknown woman's/man's name, and two unfamiliar figures. After the tests, the Romantic Jealousy Scale was applied. Participants classified as having a higher degree of jealousy did not form equivalence classes regardless of whether they were men or women. It is suggested that pre-experimental relations with affective functions interfere in the formation of equivalence classes in which the boyfriend's/girlfriend's name should be related to the unknown woman's/man's name.

Mantis: A Fast, Small, and Exact Large-Scale Sequence-Search Index.

Sequence-level searches on large collections of RNA sequencing experiments, such as the NCBI Sequence Read Archive (SRA), would enable one to ask many questions about the expression or variation of a given transcript in a population. Existing approaches, such as the sequence Bloom tree, suffer from fundamental limitations of the Bloom filter, resulting in slow build and query times, less-than-optimal space usage, and potentially large numbers of false-positives. This paper introduces Mantis, a space-efficient system that uses new data structures to index thousands of raw-read experiments and facilitates large-scale sequence searches. In our evaluation, index construction with Mantis is 6× faster and yields a 20% smaller index than the state-of-the-art split sequence Bloom tree (SSBT). For queries, Mantis is 6-108× faster than SSBT and has no false-positives or -negatives. For example, Mantis was able to search for all 200,400 known human transcripts in an index of 2,652 RNA sequencing experiments in 82 min; SSBT took close to 4 days.

The processing of positional information in a two-item sequence limits the emergence of symmetry in baboons (Papio papio), but not in humans (Homo sapiens).

When trained to associate Stimulus A to Stimulus B, humans can derive the untrained symmetrical B to A relation while nonhuman animals have much more difficulties. Urcuioli (2008, Journal of the Experimental Analysis of Behavior, 90, 257--282; 2015, Conductal, 3, 4--25) proposed that the apparent difficulty of animals in symmetry testing reflects their double encoding of the information on the stimuli (identity and relation) and their positional (i.e., spatial and temporal/ordinal) characteristics. This comparative study tested the emergence of symmetry in humans and baboons in a task in which the position of the stimuli was manipulated independently of their relation. Humans and baboons initially learned to associate pairs of visual shapes on a touch screen in a specific order. Three pairs of (A-B, C-D, and E-F) stimuli were used in training. After training, the two species were tested with the B-A, F-C, and E-D pairs. The B-A pairs preserved the association initially learned with A-B but reversed the positional information relative to training. The F-C pair neither preserved the association nor the positional information of the training pairs, and positional information were the only cues preserved in the E-D pair. Humans showed a response time advantage for B-A, suggesting symmetry, but also for E-D, suggesting that they also process positional information. In baboons, the advantage was found only for E-D, suggesting that they only process positional information. These results confirm that the processing of stimulus pairs differ between nonhuman animals to humans.

Meaningful Stimuli and the Enhancement of Equivalence Class Formation.

Stimulus meaningfulness has been defined by its hedonic valence, denotative (definitional) and connotative (evaluative) properties, and its influence on forming categories called equivalence classes. Positive or negative hedonic value of a meaningful stimulus transfers to the other members of an equivalence class that contains such a stimulus, and also influences likelihood of class formation. The denotative and connotative properties of meaningful stimuli are instantiated by the responses they produced (simple discriminative functions) and by the selection of other related words (conditional discriminative functions). If a meaningless cue acquires one such stimulus control function, and is included in a set of otherwise meaningless stimuli, its inclusion enhances the formation of an equivalence class. These results suggest ways to enhance equivalence class formation in applied settings. When degree of enhancement matches that produced by the inclusion of a meaningful stimulus in a class, class enhancement can be accounted for by the stimulus control functions it serves, as well as its hedonic, denotative, and connotative properties. We also linked equivalence class formation and meaningfulness to semantic networks, relational frame theory, verbal behavior, and naming.

A Neurocomputational Approach to Trained and Transitive Relations in Equivalence Classes.

A stimulus class can be composed of perceptually different but functionally equivalent stimuli. The relations between the stimuli that are grouped in a class can be learned or derived from other stimulus relations. If stimulus A is equivalent to B, and B is equivalent to C, then the equivalence between A and C can be derived without explicit training. In this work we propose, with a neurocomputational model, a basic learning mechanism for the formation of equivalence. We also describe how the relatedness between the members of an equivalence class is developed for both trained and derived stimulus relations. Three classic studies on stimulus equivalence are simulated covering typical and atypical populations as well as nodal distance effects. This model shows a mechanism by which certain stimulus associations are selectively strengthened even when they are not co-presented in the environment. This model links the field of equivalence classes to accounts of Hebbian learning and categorization, and points to the pertinence of modeling stimulus equivalence to explore the effect of variations in training protocols.

Ensombreciendo el surgimiento de clases de equivalencia / Overshadowing the formation of equivalence classes

Investigaciones actuales postulan que el condicionamiento respondiente (CR) es suficiente para establecer clases de equivalencia de estímulos (CEE). A su vez, el fenómeno de ensombrecimiento no se ha estudiado dentro del contexto de aprendizaje de CEE. Estudiar la influencia de procesos propios del CR se plantea como una forma de evaluar esta hipótesis. Tres clases de tres estímulos fueron entrenadas mediante una tarea de emparejamiento con la muestra. Cada clase estuvo compuesta por dos estímulos simples y un estímulo compuesto, conformado por dos estímulos de distinta saliencia. Luego se evaluó la emergencia de relaciones derivadas para los estímulos saliente y ensombrecido. La emergencia de CEE se observó en cuatro de 13 sujetos para el estímulo saliente y en ninguno para el estímulo ensombrecido. Estos resultados demuestran que la emergencia de relaciones derivadas es sensible al ensombrecimiento, y aporta evidencia respecto del rol del CR en la formación de CEE.

Current researches postulate that respondent conditioning (RC) is sufficient to establish Stimuli Equivalence Classes (SEC). In turn, the influency of the the overshadowing phenomenon has not been studied within the learning context of SEC. Studying the influence of RC\'s processes is posed as a way of evaluating this hypothesis. Three classes of three stimuli were trained through a matching to sample task. Each class consisted of two simple stimuli and one compound stimulus, consisting of two stimuli of different salience. The emergence of derived relationships for salient and overshadowed stimuli was then evaluated. Emergence of SEC was observed in four of 13 subjects for the salient stimuli and in none for the overshadowed stimuli. These results shown that the emergence of derived relationships is sensitive to overshadowing, and provides evidence regarding the role of RC in the formation of SEC.

Effects of mastery criterion on the emergence of derived equivalence relations.

In this study, we manipulated mastery criterion form (rolling or block) and stringency (across 6 or 12 trials) and measured the emergence of derived relations. College students learned neuroanatomy equivalence classes and experienced one of two rolling mastery criteria (6 or 12 consecutive correct responses) or a block mastery criterion (12 trials in a block) during training. The study found that block and rolling mastery criteria produced similar outcomes. Effectiveness was hampered when the criterion was less stringent.

Behavior analysis and neuroscience: Complementary disciplines.

Behavior analysis and neuroscience are disciplines in their own right but are united in that both are subfields of a common overarching field-biology. What most fundamentally unites these disciplines is a shared commitment to selectionism, the Darwinian mode of explanation. In selectionism, the order and complexity observed in nature are seen as the cumulative products of selection processes acting over time on a population of variants-favoring some and disfavoring others-with the affected variants contributing to the population on which future selections operate. In the case of behavior analysis, the central selection process is selection by reinforcement; in neuroscience it is natural selection. The two selection processes are inter-related in that selection by reinforcement is itself the product of natural selection. The present paper illustrates the complementary nature of behavior analysis and neuroscience through considering their joint contributions to three central problem areas: reinforcement-including conditioned reinforcement, stimulus control-including equivalence classes, and memory-including reminding and remembering.

Classes funcionais e de equivalência emcrianças diagnosticadas com autismo / Functional and equivalence classes in children diagnosed with autism

A possível identidade entre classe de equivalência e classes funcionais é condizente com a proposta de que todos os elementos arbitrariamente relacionados nas contingências podem participar das classes. O presente trabalho investigou a formação de classes de estímulos por meio do procedimento de reversões de discriminações simples – RRDS - e sua expansão tanto via RRDS quanto por matching-to-sample (MTS). Participaram do estudo duas crianças com diagnóstico de Transtorno do Espectro Autista. Foram realizados os treinos de RRDS (estímulos A, B, C e D); teste de formação de classes funcionais e teste de relações de equivalência; treino de MTS e RRDS com estímulos novos e testes de expansão de classes nos dois procedimentos. Ambos os participantes mostraram evidências da formação e expansão de classes. Esse conjunto de dados sugere que achados documentando classes funcionais e classes de equivalência refletem o mesmo fenômeno comportamental (substituibilidade de elementos arbitrariamente relacionados) via procedimentos diferentes. (AU)

The possible identity between functional and equivalence classes is consistent with the proposal that all elements arbitrarily related in the contingence can participate in the classes. The present study investigated stimulus class formation via repeated reversals of simple discrimination procedure - RRSD - and its expansion through both RRSD and matching to sample (MTS) procedure. Two children diagnosed with Autism Spectrum Disorder participated in this study. We carried out RRDS training stimulus sets A, B, C, and D); tests for functional class and equivalence class formation; MTS and RRSD training with new stimuli; and tests for class expansion in both procedures. Both participants showed evidence of class formation and expansion. This data suggest that findings documenting functional and equivalence classes reflect the same behavioral phenomena (substitutability of arbitrarily related elements) via different procedures. (AU)

Classes funcionais e de equivalência em crianças diagnosticadas com autismo / Functional and equivalence classes in children diagnosed with autism

A possível identidade entre classe de equivalência e classes funcionais é condizente com a proposta de que todos os elementos arbitrariamente relacionados nas contingências podem participar das classes. O presente trabalho investigou a formação de classes de estímulos por meio do procedimento de reversões de discriminações simples – RRDS - e sua expansão tanto via RRDS quanto por matching-to-sample (MTS). Participaram do estudo duas crianças com diagnóstico de Transtorno do Espectro Autista. Foram realizados os treinos de RRDS (estímulos A, B, C e D); teste de formação de classes funcionais e teste de relações de equivalência; treino de MTS e RRDS com estímulos novos e testes de expansão de classes nos dois procedimentos. Ambos os participantes mostraram evidências da formação e expansão de classes. Esse conjunto de dados sugere que achados documentando classes funcionais e classes de equivalência refletem o mesmo fenômeno comportamental (substituibilidade de elementos arbitrariamente relacionados) via procedimentos diferentes.

The possible identity between functional and equivalence classes is consistent with the proposal that all elements arbitrarily related in the contingence can participate in the classes. The present study investigated stimulus class formation via repeated reversals of simple discrimination procedure - RRSD - and its expansion through both RRSD and matching to sample (MTS) procedure. Two children diagnosed with Autism Spectrum Disorder participated in this study. We carried out RRDS training stimulus sets A, B, C, and D); tests for functional class and equivalence class formation; MTS and RRSD training with new stimuli; and tests for class expansion in both procedures. Both participants showed evidence of class formation and expansion. This data suggest that findings documenting functional and equivalence classes reflect the same behavioral phenomena (substitutability of arbitrarily related elements) via different procedures.

Equivalência de estímulos e ciúme: efeito de história pré-experimental / Stimulus equivalence and jealousy: effect of pre-experimental history

A formação de classes de estímulos equivalentes tem sido usada como modelo experimental para investigar uma série de fenômenos comportamentais, tais como o desenvolvimento de comportamento simbólico e a transferência de funções que os eventos ambientais adquirem por meio de relações condicionais. O objetivo deste estudo consistiu em analisar o efeito de estímulos com alto grau afetivo pré-experimentalmente constituído, na formação de classes de equivalência estabelecidas em contexto experimental, quando as relações emergentes podem se caracterizar por um conflito na escolha dos estímulos. Participaram 17 estudantes universitários que foram submetidos ao procedimento de escolha de acordo com modelo e aos testes das relações emergentes, para formar quatro classes de equivalência com quatro estímulos cada. Verificou-se que 10 dos 17 participantes formaram as classes equivalentes e observou-se correlação positiva entre o desempenho no Teste de Equivalência e o escore na Escala de Ciúme Romântico, sugerindo que a história pré-experimental referente ao envolvimento afetivo interferiu no desempenho dos participantes. O efeito de interferência provavelmente é devido ao conflito entre contingências: uma que controla o responder diante de relações condicionais pré-experimentalmente estabelecidas, envolvendo estímulos com alto valor afetivo, e outra estabelecida no contexto experimental.

The formation of stimulus equivalence classes has been used as an experimental model to investigate a series of behavioral phenomena, such as the development of symbolic behavior and transfer of functions that environmental events acquire through conditional relations. The aim of this study was to analyze the effect of stimuli with high pre-experimentally constituted affective grade in the formation of equivalence classes established in an experimental context, when the emergent relations can be characterized by a conflict in choosing stimuli. Participants were 17 college students exposed to matching to sample procedure and the tests of emergent relations to form four equivalence classes with four stimuli each. The results showed that 10 out of 17 participants formed equivalence classes, and positive correlation was observed between the performance on the Equivalence Test and the score on the Romantic Jealousy Scale, suggesting that the pre-experimental history related to emotional involvement interfered with participants' performance. The interference effect is probably due to the conflict between contingencies: one that controls responses to pre-experimentally established conditional relations involving stimuli with high emotional value, and another one, established in the experimental setting.

Transferencia de funciones sintácticas artificiales entre estímulos relacionados por equivalencia: Un estudio de potenciales cerebrales relacionados con eventos / Transfer of artificial syntax functions among equivalence - related stimuli: An event - related brain potentials study

La formación de clases de equivalencia entre estímulos ha sido propuesta en el campo del Análisis Experimental del Comportamiento como un prerrequisito conductual para el lenguaje. Adicionalmente, existe evidencia de que la transferencia de función entre estímulos equivalentes podría explicar la adquisición de estructuras sintácticas simples. No obstante, la simplicidad de las funciones sintácticas estudiadas no capturó la complejidad combinatoria de la gramática natural. Si la transferencia de funciones en clases de equivalencia es un modelo posible del desarrollo de estructuras gramaticales, debería ser verificado en contextos más válidos para el estudio del lenguaje. Los objetivos del trabajo realizado fueron los siguientes: (1) analizar la transferencia de funciones sintácticas en clases de equivalencia en un contexto válido para el estudio de la adquisición de reglas gramaticales, utilizando para ello el paradigma de gramáticas artificiales y (2) analizar los potenciales cerebrales relacionados con el procesamiento de esta transferencia de función, en secuencias gramaticales y no gramaticales. Se encontró evidencia comportamental de transferencia de función en un subgrupo de los sujetos experimentales. El potencial P600, típicamente asociado al costo de integración sintáctica en contextos lingüísticos, fue observado en estos sujetos ante: violaciones gramaticales con estímulos originales de la gramática artificial y secuencias con estímulos relacionados por equivalencia (gramaticales y no gramaticales). Se interpretó que el procesamiento de las secuencias artificiales implicó mecanismos neurobiológicos similares a los asociados a la sintaxis del lenguaje y que el patrón de actividad P600 observado puede ser explicado por el aumento del costo de integración de los estímulos al contexto previo.

Stimulus equivalence class formation has been proposed as a behavioral prerequisite for language within the field of experimental analysis of behavior. Additionally, there is evidence that transfer of function among equivalent stimuli may explain acquisition of simple syntactic structures. However these experiments analyzed sequence functions that did not capture the complexity and versatility of natural grammar. If transfer of function between stimuli that belong to the same equivalence classes is indeed a useful model for the development of grammatical structures, then we should be able to verify it in a more valid context for the study of language. Artificial grammar learning tasks have been applied to the study of several aspects of language acquisition, from word segmentation to phrase structure and syntax rules. Furthermore, it has been shown that patterns of brain activity during processing of artificial grammars resemble those observed in language syntax processing. In particular, structural violations of language sentences and artificial grammar sequences both activate Broca's area. Therefore, artificial grammars provide a valid paradigm to study the learning of syntactic functions. The main objectives of the current work were: (1) to analyze transfer of function within equivalence classes in a valid context for the study of syntax acquisition, applying the artificial grammar paradigm and (2) to analyze brain potentials related to the transfer of function in grammatical and ungrammatical sequences. Fifteen subjects were trained to form two three-stimulus equivalence classes and then performed an artificial grammar learning task. One stimulus from each equivalence class was included as an item in the artificial grammar categories. During a test stage, subjects were asked to classify new artificial grammar sequences as grammatical or ungrammatical, while their EEG activity was registered. Half of these new sequences were built using the original training items and the other half contained equivalence-related stimulus. Subjects were assigned to two groups according to their performance in this test stage. Those participants whose percentage of correct responses was above 50 % were considered to pass, while those below were assigned to the fail group. We found behavioral evidence of transfer of function in the pass subgroup. These participants were able to correctly discriminate grammatical from un grammatical sequences that were built using original or equivalence-related stimulus. Event-Related potential Analysis of the EEG signal indicated a posteriorly distributed positivity with a topography and time-course similar to the P600 potential. Within linguistic contexts, P600 is interpreted as the neural correlate of prediction and integration costs during syntax processing. It has been proposed that sentence comprehension depends on predictive mechanisms that combine lexical, semantic and syntactic information from linguistic input to anticipate future words. Processing of incoming stimuli is facilitated by pre- activation, allowing rapid integration to previous context. However, when the input does not match predictions, this integration becomes slower and more difficult, requiring additional neural resources. The P600 has been considered and index of increased integration costs, generated by unfulfilled predictions of word category and morphology based on previous context. In the present experiment, the P600 was observed after: grammar violations with the original artificial grammar lexicon and artificial sequences containing equivalence-related stimulus (both grammatical and ungrammatical). Results showed that artificial grammar processing involved neurobiological mechanisms that are similar to those associated in natural grammar processing. We interpreted the observed P600 pattern in terms of an increased stimulus integration cost, both in the case of grammatical and ungrammatical equivalence-related stimulus. Even though we consider that transference of function and equivalence class formations are by themselves insufficient to explain the complexity of natural grammar, we propose that this processes might be relevant to its acquisition and evolution, constituting a behavioral prerequisite for language development.

Transferencia de funciones sintácticas artificiales entre estímulos relacionados por equivalencia: Un estudio de potenciales cerebrales relacionados con eventos / Transfer of artificial syntax functions among equivalence - related stimuli: An event - related brain potentials study

La formación de clases de equivalencia entre estímulos ha sido propuesta en el campo del Análisis Experimental del Comportamiento como un prerrequisito conductual para el lenguaje. Adicionalmente, existe evidencia de que la transferencia de función entre estímulos equivalentes podría explicar la adquisición de estructuras sintácticas simples. No obstante, la simplicidad de las funciones sintácticas estudiadas no capturó la complejidad combinatoria de la gramática natural. Si la transferencia de funciones en clases de equivalencia es un modelo posible del desarrollo de estructuras gramaticales, debería ser verificado en contextos más válidos para el estudio del lenguaje. Los objetivos del trabajo realizado fueron los siguientes: (1) analizar la transferencia de funciones sintácticas en clases de equivalencia en un contexto válido para el estudio de la adquisición de reglas gramaticales, utilizando para ello el paradigma de gramáticas artificiales y (2) analizar los potenciales cerebrales relacionados con el procesamiento de esta transferencia de función, en secuencias gramaticales y no gramaticales. Se encontró evidencia comportamental de transferencia de función en un subgrupo de los sujetos experimentales. El potencial P600, típicamente asociado al costo de integración sintáctica en contextos ling³ísticos, fue observado en estos sujetos ante: violaciones gramaticales con estímulos originales de la gramática artificial y secuencias con estímulos relacionados por equivalencia (gramaticales y no gramaticales). Se interpretó que el procesamiento de las secuencias artificiales implicó mecanismos neurobiológicos similares a los asociados a la sintaxis del lenguaje y que el patrón de actividad P600 observado puede ser explicado por el aumento del costo de integración de los estímulos al contexto previo.(AU)

Stimulus equivalence class formation has been proposed as a behavioral prerequisite for language within the field of experimental analysis of behavior. Additionally, there is evidence that transfer of function among equivalent stimuli may explain acquisition of simple syntactic structures. However these experiments analyzed sequence functions that did not capture the complexity and versatility of natural grammar. If transfer of function between stimuli that belong to the same equivalence classes is indeed a useful model for the development of grammatical structures, then we should be able to verify it in a more valid context for the study of language. Artificial grammar learning tasks have been applied to the study of several aspects of language acquisition, from word segmentation to phrase structure and syntax rules. Furthermore, it has been shown that patterns of brain activity during processing of artificial grammars resemble those observed in language syntax processing. In particular, structural violations of language sentences and artificial grammar sequences both activate Brocas area. Therefore, artificial grammars provide a valid paradigm to study the learning of syntactic functions. The main objectives of the current work were: (1) to analyze transfer of function within equivalence classes in a valid context for the study of syntax acquisition, applying the artificial grammar paradigm and (2) to analyze brain potentials related to the transfer of function in grammatical and ungrammatical sequences. Fifteen subjects were trained to form two three-stimulus equivalence classes and then performed an artificial grammar learning task. One stimulus from each equivalence class was included as an item in the artificial grammar categories. During a test stage, subjects were asked to classify new artificial grammar sequences as grammatical or ungrammatical, while their EEG activity was registered. Half of these new sequences were built using the original training items and the other half contained equivalence-related stimulus. Subjects were assigned to two groups according to their performance in this test stage. Those participants whose percentage of correct responses was above 50 % were considered to pass, while those below were assigned to the fail group. We found behavioral evidence of transfer of function in the pass subgroup. These participants were able to correctly discriminate grammatical from un grammatical sequences that were built using original or equivalence-related stimulus. Event-Related potential Analysis of the EEG signal indicated a posteriorly distributed positivity with a topography and time-course similar to the P600 potential. Within linguistic contexts, P600 is interpreted as the neural correlate of prediction and integration costs during syntax processing. It has been proposed that sentence comprehension depends on predictive mechanisms that combine lexical, semantic and syntactic information from linguistic input to anticipate future words. Processing of incoming stimuli is facilitated by pre- activation, allowing rapid integration to previous context. However, when the input does not match predictions, this integration becomes slower and more difficult, requiring additional neural resources. The P600 has been considered and index of increased integration costs, generated by unfulfilled predictions of word category and morphology based on previous context. In the present experiment, the P600 was observed after: grammar violations with the original artificial grammar lexicon and artificial sequences containing equivalence-related stimulus (both grammatical and ungrammatical). Results showed that artificial grammar processing involved neurobiological mechanisms that are similar to those associated in natural grammar processing. We interpreted the observed P600 pattern in terms of an increased stimulus integration cost, both in the case of grammatical and ungrammatical equivalence-related stimulus. Even though we consider that transference of function and equivalence class formations are by themselves insufficient to explain the complexity of natural grammar, we propose that this processes might be relevant to its acquisition and evolution, constituting a behavioral prerequisite for language development.(AU)

Aprendizaje de clases de equivalencia de redes bayesianas basado en búsqueda competitiva de hormigas artificiales / Learning of bayesian networks equivalence classes based on competitive search of artificial ants

Este artículo propone un algoritmo de aprendizaje de clases de equivalencia de redes bayesianas basado en un algoritmo de búsqueda Greedy y modelos de búsqueda inspirados en hormigas competitivas. Específicamente para el algoritmo propuesto, se obtuvo una mejor aproximación entre la red predicha y la red bayesiana teórica de ejemplo ASIA, con respecto a algoritmos anteriores, para conjuntos de datos con 20 y 500 muestras. En promedio el algoritmo desarrollado obtuvo una aproximación con respecto a la distancia estructural de hamming de 10.7% y 5.3% menor comparada con la obtenida por los algoritmos Greedy y de colonia de hormigas (ACO-E) respectivamente para 20 muestras, y de hasta el 6.8% menor con respecto al algoritmo ACO-E para 500 muestras. Además, para 500 muestras el número de llamadas a la función de puntaje realizadas por el algoritmo propuesto fue menor que las realizadas por el algoritmo ACO-E en el 90% de las combinaciones, concluyendo que hubo una reducción de la complejidad computacional. Finalmente se presentan los resultados de la aplicación del algoritmo propuesto a un microarreglo obtenido por muestras de pacientes con Leucemia Mieloide Aguda (LMA) con 6 nuevas interacciones con dependencias estadísticas como potenciales interacciones biológicas con alta probabilidad.

This article proposes an algorithm for learning equivalence classes of Bayesian networks based on a Greed search algorithm and search patterns inspired by competitive ants. Specifically, for the proposed algorithm, we obtained a better approximation between the predicted network and the theoretical network ASIA with respect to previous algorithms for data sets with 20 and 500 samples. On average, the algorithm developed an approximation with respect to Structural Hamming Distance of 10.7% and 5.3% lower than Greedy algorithms and ACO-E respectively to 20 samples, and up to 6.8% lower tan ACO-E algorithm for 500 samples. Furthermore, for 500 samples the number of calls to the scoring function performed by the algorithm proposed was smaller than in the ACO-E algorithm in 90% of the combinations, concluding that there was a reduction in the computational complexity. Finally, we present the results of applying the proposed algorithm to a microarray samples obtained from patients with acute myeloid leukemia (AML) with 6 new interactions with statistical dependencies as potential biological interactions with high probability.

Efeito da escolha da opção "nenhuma das alternativas" sobre a ressurgência de classes de equivalência / Effect of choosing the "none of the alternatives" option on equivalence classes resurgence

A ressurgência de classes de equivalência tem sido demonstrada sob contingência de punição, mas raramente sob extinção. Uma explicação seriam as condições extremamente controladas dos arranjos experimentais, em que o participante é obrigado a escolher um dos estímulos de comparação. O objetivo deste estudo foi investigar o efeito de uma opção de resposta correspondente a não escolher um dos estímulos de comparação ("nenhuma das alternativas"), sobre a emergência de relações de equivalência e o efeito dessa opção sobre a ressurgência de classes de equivalência sob extinção ou punição. Dois grupos de seis participantes cada foram submetidos a um procedimento de escolha de acordo com modelo (MTS). Na Etapa 1 (Treino Inicial), relações condicionais para formar quatro classes com quatro estímulos foram reforçadas. Na Etapa 2 (Treino Tardio), as contingências foram alteradas e os 16 estímulos foram recombinados para formar quatro classes de equivalência novas. Na Etapa 3 (Ressurgência), os participantes foram expostos ao MTS sob extinção (Grupo 1) ou punição (Grupo 2) das repostas de acordo com o Treino Tardio. Durante os testes de equivalência e na condição de Ressurgência, a opção "nenhuma das alternativas" estava presente. Os dois grupos demonstraram emergência das classes de equivalência na Etapa 1. Na Etapa 3, cinco dos seis participantes do Grupo 1 não demonstraram ressurgência, mas no caso dos participantes do Grupo 2 esse fenômeno foi observado. A opção "nenhuma das alternativas" foi raramente escolhida. Conclui-se que a presença dessa opção não afetou a formação ou a ressurgência de classes de equivalência.(AU)

The resurgence of equivalence classes has been demonstrated under a punishment contingency, but rarely under extinction. One explanation would be the extremely controlled experimental settings in which the participant is required to choose one of the comparison stimuli presented. The goals of this study were to investigate the effects of a response option corresponding to choosing none of the comparison stimuli ('no alternative') on the emergence of equivalence relations, and the effects of this option on the resurgence of equivalence classes under punishment or extinction. Two groups of six participants each were exposed to three phases of a matching-to-sample (MTS) procedure. In Phase 1 (Early-training), conditional relations were trained to establish four equivalence classes with four visual stimuli. In Phase 2 (Late-training), the contingencies were changed and these 16 stimuli were recombined to form four new equivalence classes. In Phase 3 (Resurgence), participants were exposed to MTS trials under extinction (Group 1) or punishment (Group 2) of the Late-training-consistent responses. During equivalence relations tests and the resurgence condition the "no alternative" option was presented. Both groups showed emergence of the equivalence classes in Phase1. In Phase 3, five of six participants in Group 1 showed no resurgence of Early-training-consistent responses, but in the case of participants in Group 2 this phenomenon was observed. The "no alternative" response was rarely emitted. It was concluded that the presence of this option did not affect the formation or the resurgence of equivalence classes.(AU)

El resurgimiento de las clases de equivalencia se ha demostrado en la contingencia de castigo, pero rara vez en la extinción. Una explicación podría ser las condiciones muy controladas de las disposiciones experimentales, en el que el participante está obligado a elegir uno de los estímulos de comparación. El objetivo de este estudio fue investigar el efecto de una opción de respuesta correspondiente de no elegir uno de los estímulos de comparación ("ninguna de las alternativas"), en el surgimiento de relaciones de equivalencia y el efecto de esta opción en el resurgimiento de las clases de equivalencia con la extinción o el castigo. Dos grupos de seis participantes cada uno se sometió a un procedimiento de igualación de la muestra (MTS). En el Paso 1 (Entrenamiento Inicial), las relaciones condicionales para formar cuatro clases con cuatro estímulos fueron reforzadas. En el Paso 2 (Entrenamiento Tardío), las contingencias se han cambiado y los 16 estímulos fueron recombinados para formar cuatro nuevas clases de equivalencia. En el Paso 3 (Resurgimiento), los participantes fueron expuestos a ensayos de MTS en extinción (Grupo 1) o castigo (Grupo 2) de las respuestas consistentes con el Entrenamiento Tardío. Durante las pruebas de equivalencia y la condición de resurgimiento, la opción "ninguna de las alternativas" estuvo presente. Ambos grupos demostraron el resurgimiento de las clases de equivalencia en el Paso 1. En el Paso 3, cinco de los seis participantes en el Grupo 1 no mostró resurgimiento, pero en el caso de los participantes del Grupo 2 este fenómeno se observó. La opción "ninguna de las alternativas" fue elegido en raras ocasiones. Se concluyó que la presencia de esta opción no afectó a la formación o el resurgimiento de las clases de equivalencia.(AU)

Efeito da escolha da opção "nenhuma das alternativas" sobre a ressurgência de classes de equivalência / Effect of choosing the "none of the alternatives" option on equivalence classes resurgence / Efecto de elegir la opción "ninguna de las alternativas" en el resurgimiento de las clases de equivalencia

A ressurgência de classes de equivalência tem sido demonstrada sob contingência de punição, mas raramente sob extinção. Uma explicação seriam as condições extremamente controladas dos arranjos experimentais, em que o participante é obrigado a escolher um dos estímulos de comparação. O objetivo deste estudo foi investigar o efeito de uma opção de resposta correspondente a não escolher um dos estímulos de comparação ("nenhuma das alternativas"), sobre a emergência de relações de equivalência e o efeito dessa opção sobre a ressurgência de classes de equivalência sob extinção ou punição. Dois grupos de seis participantes cada foram submetidos a um procedimento de escolha de acordo com modelo (MTS). Na Etapa 1 (Treino Inicial), relações condicionais para formar quatro classes com quatro estímulos foram reforçadas. Na Etapa 2 (Treino Tardio), as contingências foram alteradas e os 16 estímulos foram recombinados para formar quatro classes de equivalência novas. Na Etapa 3 (Ressurgência), os participantes foram expostos ao MTS sob extinção (Grupo 1) ou punição (Grupo 2) das repostas de acordo com o Treino Tardio. Durante os testes de equivalência e na condição de Ressurgência, a opção "nenhuma das alternativas" estava presente. Os dois grupos demonstraram emergência das classes de equivalência na Etapa 1. Na Etapa 3, cinco dos seis participantes do Grupo 1 não demonstraram ressurgência, mas no caso dos participantes do Grupo 2 esse fenômeno foi observado. A opção "nenhuma das alternativas" foi raramente escolhida. Conclui-se que a presença dessa opção não afetou a formação ou a ressurgência de classes de equivalência.

The resurgence of equivalence classes has been demonstrated under a punishment contingency, but rarely under extinction. One explanation would be the extremely controlled experimental settings in which the participant is required to choose one of the comparison stimuli presented. The goals of this study were to investigate the effects of a response option corresponding to choosing none of the comparison stimuli ('no alternative') on the emergence of equivalence relations, and the effects of this option on the resurgence of equivalence classes under punishment or extinction. Two groups of six participants each were exposed to three phases of a matching-to-sample (MTS) procedure. In Phase 1 (Early-training), conditional relations were trained to establish four equivalence classes with four visual stimuli. In Phase 2 (Late-training), the contingencies were changed and these 16 stimuli were recombined to form four new equivalence classes. In Phase 3 (Resurgence), participants were exposed to MTS trials under extinction (Group 1) or punishment (Group 2) of the Late-training-consistent responses. During equivalence relations tests and the resurgence condition the "no alternative" option was presented. Both groups showed emergence of the equivalence classes in Phase1. In Phase 3, five of six participants in Group 1 showed no resurgence of Early-training-consistent responses, but in the case of participants in Group 2 this phenomenon was observed. The "no alternative" response was rarely emitted. It was concluded that the presence of this option did not affect the formation or the resurgence of equivalence classes.

El resurgimiento de las clases de equivalencia se ha demostrado en la contingencia de castigo, pero rara vez en la extinción. Una explicación podría ser las condiciones muy controladas de las disposiciones experimentales, en el que el participante está obligado a elegir uno de los estímulos de comparación. El objetivo de este estudio fue investigar el efecto de una opción de respuesta correspondiente de no elegir uno de los estímulos de comparación ("ninguna de las alternativas"), en el surgimiento de relaciones de equivalencia y el efecto de esta opción en el resurgimiento de las clases de equivalencia con la extinción o el castigo. Dos grupos de seis participantes cada uno se sometió a un procedimiento de igualación de la muestra (MTS). En el Paso 1 (Entrenamiento Inicial), las relaciones condicionales para formar cuatro clases con cuatro estímulos fueron reforzadas. En el Paso 2 (Entrenamiento Tardío), las contingencias se han cambiado y los 16 estímulos fueron recombinados para formar cuatro nuevas clases de equivalencia. En el Paso 3 (Resurgimiento), los participantes fueron expuestos a ensayos de MTS en extinción (Grupo 1) o castigo (Grupo 2) de las respuestas consistentes con el Entrenamiento Tardío. Durante las pruebas de equivalencia y la condición de resurgimiento, la opción "ninguna de las alternativas" estuvo presente. Ambos grupos demostraron el resurgimiento de las clases de equivalencia en el Paso 1. En el Paso 3, cinco de los seis participantes en el Grupo 1 no mostró resurgimiento, pero en el caso de los participantes del Grupo 2 este fenómeno se observó. La opción "ninguna de las alternativas" fue elegido en raras ocasiones. Se concluyó que la presencia de esta opción no afectó a la formación o el resurgimiento de las clases de equivalencia.