Function transfer in human operant experiments: the role of stimulus pairings

A Review of Backward Higher-Order Conditioning: Implications for a Pavlovian Conditioning Analysis of Stimulus Equivalence

Stimulus equivalence (SE) is demonstrated when participants exposed to conditional discrimination training pass tests for reflexivity, symmetry, transitivity, and equivalence (symmetry combined with transitivity). Most theorists attribute the origin of SE to operant processes, but some argue that it results from Pavlovian conditioning. Symmetry is problematic for the latter hypothesis because it seems to require excitatory backward conditioning. However, equivalence tests resemble backward sensory preconditioning (BSP) and backward second-order conditioning (BSOC), two well-established processes. A review of associationistic theories of BSP and BSOC showed that the temporal coding hypothesis (TCH) explains outcomes that other associationistic theories cannot explain (i.e., BSOC and BSP effects after first-order conditioning with delay vs. trace conditioning and forward vs. backward conditioning). The TCH assumes that organisms encode the temporal attributes of stimulus events (e.g., order and interval duration) and this temporal information is integrated across separate phases of training. The TCH seems compatible with a behavioral analysis if direct stimulus control replaces the notion of temporal maps. The TCH perspective does not seem applicable to SE because SE tests are not predictive tasks. This suggests that SE is fundamentally different from BSP and BSOC and a Pavlovian conditioning analysis of SE is inadequate. This conclusion is consistent with previous criticism of a Pavlovian account of SE according to which Pavlovian conditioning cannot be interpreted as stimulus substitution.

Emergent Relations between Discriminative Stimuli, Responses, and Consequences in Intraverbals

We explored the emergence of relations between stimuli learned as discriminative, responses, and consequences with intraverbals. In Experiment 1, five 9- and 10-year-old children learned intraverbals that related a country (A) with a city (B)—e.g., “Name a city of Switzerland”; “Davos”—and that country with a predator animal (C). Correct responses were followed by saying the name of a feature of the city (T) or saying an animal preyed by the predator (U), respectively. The emergence of BC and CB intraverbals that relate the cities and the predators and that of intraverbals that relate the specific consequences to the cities (T-B and U-B) and to the prey animals (T-C and U-C) was probed with no differential consequences. All five children demonstrated the emergence of BC, CB, U-B, and U-C and four children also demonstrated the emergence of T-B and T-C. In Experiment 2, a simpler procedure that controlled a possible extraneous factor, was used with seven 7- and 8-year old children and they also demonstrated emergence. Thus, the emergence of verbal relations with elements taught as discriminative stimuli, responses, and consequences was demonstrated.

Establishing derived reinforcers via stimulus equivalence

If one of several stimuli in an equivalence class acquires a function, it transfers to all members of the respective class. Even though research has demonstrated this transfer across a variety of stimulus functions (e.g., discriminative), few studies have focused on the transfer of the reinforcing function. The current study extended previous literature by establishing derived reinforcers using conditional discrimination training with six neurotypical adults. We established three 4-member equivalence classes and then created a discriminative stimulus in one member by correlating it with reinforcement. We also expanded classes by adding a stimulus to each class and testing its function. During the transfer of function tests, five out of six participants chose the derived reinforcers more than the other stimuli. Three participants required remedial training or testing prior to demonstrating transfer of function. Results show that stimulus equivalence training is an effective and efficient paradigm to establish derived reinforcers.

Dissociating preferences from evaluations following subliminal conditioning

Preferences towards unfamiliar drink brands may be influenced through subliminal conditioning. This can involve associating unfamiliar brands (CS) with positively valenced attributes (US) under constrained visual conditions to prevent the former's conscious detection. According to learning theory, CS associated with positive US should become increasingly preferred as the latter's positive valences generalizes (transfer) across associated CS. Similarly, correlating CS with negative US should reduce CS-associated preferences. There is some evidence that CS-associated preferences can be reliably influenced through subliminal conditioning (Elgendi et al., 2018). Conversely, there is also evidence that subliminal conditioning does not effectively alter evaluations of CS valence (Heycke et al., 2018). Those works suggest CS preferences may be more susceptible to subliminal valence transfer relative to CS evaluations. We explored this hypothesis presently, where four pairs of supraliminal/visible and subliminal trigrams (CS) were respectively associated with four US categories varied along aggregate valence (100% positive, 80% positive, 20% positive, 0% positive). CS evaluations and preferences were recorded before and after conditioning. Bayesian analyses revealed US valence manipulations were likely to shift preferences, but not evaluations, of subliminal CS. Across supraliminal CS, Bayesian and frequentist analyses indicated US valence was significant and likely to shift preferences and evaluations. The present study demonstrates preferences may be influenced through subliminal conditioning even as evaluations are not.

Why We Are Still Not Acting to Save the World: the Upward Challenge of a Post-Skinnerian Behavior Science

Basic research on derived stimulus relations reveals many effects that may be useful in understanding and resolving significant and complex societal problems. Applied research on derived stimulus relations has done little to fulfill this promise, focusing instead mainly on simple demonstrations of well-known phenomena. We trace the research tradition of derived stimulus relations from laboratory to wide-scale implementation, and put forward several suggestions for how to progress effective and impactful research on derived relational responding to issues of immense social importance. To advance a science of behavior from relative social obscurity to the developing world-saving technologies, we must evaluate our own behavior as scientists in the grander social context.

Effects of orientation and differential reinforcement II: transitivity and transfer across five-member sets

A recent report by Amd et al. (2017) demonstrated that orienting towards successively presented stimulus-stimulus pairs yielded significantly more transitive relations then when those same pairs were differentially reinforced following training for three, 3-member stimulus sets. We build on that work in four important ways. First, transitivity yields produced by Pavlovian and instrumental procedures were compared following training for three 5-member sets (A1-B1-C1-D1-E1, A2-B2-C2-D2-E2, A3-B3-C3-D3-E3), where the 'A' stimuli were emotional faces and all remaining stimuli were nonsense words. Second, our instrumental task here required two orienting/observing responses per trial. Third, we compared differences in multi-nodal transfer following Pavlovian and instrumental relational learning procedures. Finally, we tested whether functioning as 'end terms' in a relational series can mitigate transfer following instrumental conditioning. Transitivity, as measured by sorting tests, was significantly more pronounced following Pavlovian training. Transfer, assessed before and after relational training with two visual analog scales corresponding to valence and arousal dimensions, appeared marginally more robust observed for participants exposed to the Pavlovian condition. Transfer magnitude was positively related with demonstrations of transitivity, regardless of type of conditioning.

Effects of orientation and differential reinforcement on transitive stimulus control

The emergence of transitive relations between stimuli that had never appeared together is a key process underlying concept formation. An unresolved theoretical issue with respect to transitive relations has been to determine whether differential reinforcement of stimulus-stimulus (S-S) relations though matching-to-sample, or contiguous S-S correlations/pairings, is more critical for producing transitivity. The current study inquired whether simple environmental S-S pairings, versus differential reinforcement of S-S relations, versus environmental S-S pairings with an orientation requirement, produced the greatest instances of transitivity. 12 groups of participants were parsed into one of four procedures (matching-to-sample, stimulus-paring, stimulus-pairing-w/response, stimulus-pairing-w/orientation) along one of three training structures (linear, many-to-one, one-to-many). All participants underwent a fixed number of training trials for establishing three, three-member stimulus sets (A1B1C1, A2B2C2, A3B3C3), followed by a single sorting test for AC transitivity. Our results demonstrate orienting towards environmental S-S pairings yield the greatest degree of transitivity. The effectivity of pairing procedures for establishing transitive relations, particularly when compared to matching-to-sample, can inform the development of educational interventions for individuals for whom the latter procedure (involving differential reinforcement) is ineffective.

Efectos de diferentes tipos de entrenamiento en el aprendizaje de una discriminación condicional

Se diseñó un experimento para analizar el papel funcional de la retroalimentación, las instrucciones y la observación de un modelo aprendiz empleando una tarea de igualación a la muestra de segundo orden. Treinta y nueve estudiantes se asignaron aleatoriamente a uno de los tres grupos experimentales que difirieron en el entrenamiento: exposición directa a la tarea, observación de un modelo aprendiz (confederado), o uso de instrucciones precisas sobre los criterios de igualación. A algunos participantes se les ofreció un incentivo económico por su participación. Se encontró que las instrucciones precisas promovieron un aprendizaje más acelerado en comparación con los otros tipos de entrenamiento. El empleo del incentivo económico tuvo un efecto diferencial según el tipo de entrenamiento; hizo que los participantes tuvieran un mejor desempeño en la condición de observación del modelo aprendiz, pero no influyó en los otros tipos de entrenamiento. Estos resultados sugieren que el incentivo puede operar como un factor motivacional o disposicional, dado que afecta la probabilidad del establecimiento del control abstracto del estímulo.

Induction of naming after observing visual stimuli and their names in children with autism

A novel procedure to induce pairing naming, considered the emergence of tacts and selection of pictures after observing names and its corresponding pictures without specific consequences, was probed in 4 persons with autism who lacked this capability with a multiple probe design across participants. Five pictures were selected per set. The participants observed the pictures on a computer screen while the experimenter said the name of the picture. Then, the emission of untaught uninstructed tacts of the pictures was tested without reinforcement. The cycle was repeated until a criterion of 90% correct responses was achieved. Thereafter, in probes without reinforcement, the participants tacted the pictures without specific instructions and also when asked to name them, and selected the correct picture upon hearing their names. The procedure was repeated with two additional stimulus sets and the probed relations emerged always. Two children showed the emergence with fewer trials across sets, which indicate emergence induction. Thus, the procedure served to test whether the pairing naming capability was missing and induced the capability. The results may have important utility in teaching persons diagnosed with autism and other learning difficulties and for accelerating learning in all children.

Using action dynamics to assess competing stimulus control during stimulus equivalence testing

Previous studies have identified potential sources of competing stimulus control in tests for stimulus equivalence. The present experiment employed the Nintendo Wii remote (Wiimote®) to investigate whether such competition would affect suboperant action dynamics (e.g., topographies of equivalence responses). Following one-to-many training on conditional discriminations sufficient to establish three 3-member equivalence classes, participants were presented with a test for equivalence responding that included five different trial types. These included "traditional" equivalence trials, on which the incorrect stimulus had previously been presented as a correct comparison stimulus during training, trials on which a novel unrelated word was provided as the incorrect comparison, and trials on which the incorrect stimulus varied in orthographical and phonological similarity to the sample stimulus. The presence of phonological and orthographic distractor stimuli significantly reduced the probability of equivalence-consistent responding, relative to neutral distractors, but this effect was almost exclusively seen in participants who failed to demonstrate equivalence on traditional equivalence trials. Analyses of correct response trajectories suggested that the prior history of reinforcement for choosing the incorrect stimulus on the traditional equivalence trial gave rise to greater competition than did phonological or orthographic similarity between the sample and incorrect comparisons.

Stimulus pairing training for Kanji reading skills in students with developmental disabilities

Japanese students with developmental disabilities often exhibit difficulties in reading, particularly in Kanji (ideogram) reading, and in acquiring the equivalence relations between pictures, written words, and sounds. Previous research suggested that one student with autism could acquire Kanji reading along with equivalence relations through stimulus pairing training. However, maintenance rates tended to be very low, possibly due to the lack of picture stimuli. In this study, we examined the acquisition and maintenance of Kanji reading skills through stimulus pairing training using corresponding pictures for six students with developmental disabilities. We prepared stimulus pairs consisting of picture stimuli that the students could name along with a corresponding Kanji character that they could not read. All students successfully acquired and maintained the Kanji reading skills through this procedure. These findings suggest that the nameability of picture stimuli in stimulus pairing training may facilitate the acquisition and maintenance of equivalence relations for reading.

Emergent stimulus relations depend on stimulus correlation and not on reinforcement contingencies

We aimed to investigate whether novel stimulus relations would emerge from stimulus correlations when those relations explicitly conflicted with reinforced relations. In a symbolic matching-to-sample task using kanji characters as stimuli, we arranged class-specific incorrect comparison stimuli in each of three classes. After presenting either Ax or Cx stimuli as samples, choices of Bx were reinforced and choices of Gx or Hx were not. Tests for symmetry, and combined symmetry and transitivity, showed the emergence of three 3-member (AxBxCx) stimulus classes in 5 of 5 human participants. Subsequent tests for all possible emergent relations between Ax, Bx, Cx and the class-specific incorrect comparisons Gx and Hx showed that these relations emerged for 4 of 5 the participants after extended overtraining of the baseline relations. These emergent relations must have been based on stimulus-stimulus correlations, and were not properties of the trained discriminated operants, because they required control by relations explicitly extinguished during training. This result supports theoretical accounts of emergent relations that emphasize stimulus correlation over operant contingencies.

Stimulus equivalence: testing Sidman's (2000) theory

Sidman's (2000) theory regarding the origin of equivalence relations predicts that a reinforcing stimulus common to distinct equivalence classes must drop out of the equivalence relations. This prediction was tested in the present study by arranging class-specific reinforcers, R1 and R2, following correct responding on the prerequisite conditional discriminations (Ax-Bx, Cx-Bx) for two stimulus classes, A1B1C1 and A2B2C2. A class-common reinforcer, R3, was presented following correct responding on the prerequisite conditional discriminations for a further two stimulus classes, A3B3C3 and A4B4C4. Sidman's theory predicts reinforcer inclusion within Classes 1 and 2 only, given this training arrangement. Experiment 1 tested for the emergence of four equivalence classes and of stimulus-reinforcer and reinforcer-stimulus relations in each class. Four of the 6 subjects demonstrated the reinforcer-based relations in all four equivalence classes, rather than in only those classes with a class-specific reinforcer, as Sidman's theory predicts. One of the remaining 2 subjects showed the reinforcer-based relations in three of the four classes. Experiment 2 extended these findings to document the emergence of interclass matching relations based on the common reinforcer R3, in 5 of 6 subjects, such that a Class 3 sample occasioned the selection of a Class 4 sample when the Class 3 comparison was absent, and similarly, a Class 4 sample occasioned the selection of a Class 3 comparison when the Class 4 comparison was absent. These interclass relations emerged despite the simultaneous maintenance of Class 3 and 4 baseline conditional discriminations, so that the Class 3 and 4 stimuli and reinforcer simultaneously were, and were not, part of a single larger equivalence class. These data are irreconcilable with Sidman's theory, and question the utility of the application of the equivalence relation in describing derived stimulus relations.

Function transformation without reinforcement

In studies of function transformation, participants initially are taught to match stimuli in the presence of a contextual cue, X; the stimuli to be matched bear some formal relation to each other, for example, a relation of opposition or difference. In a second phase, the participants are taught to match arbitrary stimuli (say, A and B) in the presence of X. In a final test, A often displays behavioral functions that differ from those of B, and can be predicted from the nature of the relation associated with X in the initial training phase. Here we report function-transformation effects in the absence of selection responses and of their reinforcers. In three experiments with college students, exposure to relations of difference or identity modified the responses given to later stimuli. In Experiment 1, responses to a test stimulus A varied depending on preexposure to pairs of colors that were distinct from A but exemplified relations of difference or identity. In Experiment 2, a stimulus A acquired distinct functions, depending on its previous pairing with a contextual cue X that had itself been paired with identity or difference among colors. Experiment 3 confirmed the results of Experiment 2 with a modified design. Our data are consistent with the notion that relations of identity or difference can serve as stimuli for Pavlovian processes, and, in compound with other cues, produce apparent function-transformation effects.

A derived transfer of simple discrimination and self-reported arousal functions in spider fearful and non-spider-fearful participants

Two experiments investigated the derived transfer of functions through equivalence relations established using a stimulus pairing observation procedure. In Experiment 1, participants were trained on a simple discrimination (A1+/A2-) and then a stimulus pairing observation procedure was used to establish 4 stimulus pairings (A1-B1, A2-B2, B1-C1, B2-C2). Subsequently, a transfer of the simple discrimination functions through equivalence relations was observed (e.g., C1+/C2-). These procedures were modified in Experiment 2, which demonstrated that spider-fearful and non-spider-fearful participants show differing levels of a transfer of self-reported arousal functions for stimuli used in equivalence relations with video-based material depicting scenes with spiders. The results demonstrate that the stimulus pairing observation procedure provides a viable alternative to matching-to-sample, and also offer tentative support for a derived-relations model of the acquisition of anxiety responses in at least one sub-clinical population.