Differential effect of training impure tacts versus pure tacts plus intraverbal on the emergence of new verbal operants: A conceptual and methodological study.

The aim of this research was to test the effect of training impure tact versus pure tact and intraverbals on the emergence of new verbal operants (impure tacts), thus establishing a conceptual and methodological differentiation on these operants. This was done by varying the training order of intraverbal or impure tact to analyze and confirm whether or not impure tact is the mere sum of pure tact plus intraverbal and therefore has different functions and consequences in learning. An experiment was conducted with 30 participants randomly assigned to three groups. In Group 1, pure tact plus intraverbal and then impure tact were trained. In Group 3 the training order of these operants was counterbalanced. Group 2 was the control group, training only pure tact plus intraverbal. After the training phases, the emergence of impure tacts was tested. The results of this research indicate that the training of impure tacts favors the emergence of new impure tacts to a greater extent than the training of pure tact plus intraverbal and that they therefore have different functions. It is also shown that variation in the order of presentation of the type of training influences the subsequent emergence of new operants (impure tacts), so that creating a previous history of learning in impure tacts favors emergence even when the intraverbal alone is subsequently trained. This has important implications at both conceptual and methodological levels as it would contribute to the development of more effective language training technologies.

Modelling Working Memory Capacity: Is the Magical Number Four, Seven, or Does it Depend on What You Are Counting?

Limited attentional capacity is essential to working memory. How its limit should be assessed is a debated issue. Five experiments compare Cowan's 4-units and Pascual-Leone's 7-units models of limited working memory capacity, with presentation time and attention to operative schemes as potential explanations of this discrepancy. Experiments 1a-1c used the Compound Stimuli Visual Information (CSVI) task, with long versus brief presentation. Capacity was estimated with the Bose-Einstein model, assuming a different number of attending acts in each condition. Participants' k estimates in both conditions were highly correlated and the means were not different, indicating that the same capacity is assessed in both conditions. Experiments 2 and 3 used the 5000-msec CSVI, and the Visual Array Task (VAT) in two conditions (5000- vs. 120-msec presentation). Capacity in the VAT was estimated with Morey's Bayesian method. Participants' k estimates in both VAT conditions were correlated, but the mean was higher with long presentation, suggesting that the long condition benefits from recoding or chunking. The k estimate in the CSVI correlated with the short VAT and (to a lesser degree in Exp.2) with the long VAT. The mean estimate of k in the CSVI was one unit more than in the short VAT. We conclude that the CSVI and the short VAT tap the same capacity, one unit of which in the short VAT is allocated to an operative scheme; we discuss how Cowan's and Pascual-Leone's views on limited capacity can be reconciled.

Impaired Global Precedence Effect in Severe Alcohol Use Disorder and Korsakoff's Syndrome: A Pilot Exploration through a Global/Local Visual Paradigm.

In healthy populations, visual abilities are characterized by a faster and more efficient processing of global features in a stimulus compared to local ones. This phenomenon is known as the global precedence effect (GPE), which is demonstrated by (1) a global advantage, resulting in faster response times for global features than local features and (2) interference from global distractors during the identification of local targets, but not vice versa. This GPE is essential for adapting visual processing in everyday life (e.g., extracting useful information from complex scenes). We investigated how the GPE is affected in patients with Korsakoff's syndrome (KS) compared to patients with severe alcohol use disorder (sAUD). Three groups (including healthy controls, patients with KS and patients with sAUD) completed a global/local visual task in which predefined targets appeared at the global or local level during either congruent or incongruent (i.e., interference) situations. The results showed that healthy controls (N = 41) presented a classical GPE, while patients with sAUD (N = 16) presented neither a global advantage nor global interference effects. Patients with KS (N = 7) presented no global advantage and an inversion of the interference effect, characterized by strong interference from local information during global processing. The absence of the GPE in sAUD and the interference from local information in KS have implications in daily-life situations, providing preliminary data for a better understanding of how these patients perceive their visual world.

Control by Compound Antecedent Verbal Stimuli in the Intraverbal Relation.

Control by compound antecedent stimuli in verbal behavior represents an understudied but promising area of research. To date, reference to compound verbal stimulus control has generally only included descriptions of convergent multiple control. A sizeable experimental literature exists on the topic of compound stimulus control, which differs from convergent multiple control in that the stimulus elements often do not have a prior conditioning history (i.e., do not separately strengthen any response). The current study attempted to bridge the experimental and verbal behavior literatures by including a two-component antecedent verbal stimulus during intraverbal training for which neither component currently served an evocative function. Subsequent analyses of stimulus control suggested overshadowing by temporal location in the compound verbal stimulus and lack of emergence of the divergent intraverbal relation across all sets. Additional research is needed on compound stimulus control and verbal behavior researchers may be poised to answer several questions relevant to the experimental and verbal behavior literatures on the topic.

Learning Channels: The Role of Compound Stimuli in the Emergence of Intraverbal Relations in Children on the Autism Spectrum.

Teaching tact and intraverbal responses based on function-feature-class to children with language delays can result in the emergence of untrained relational responses. The purpose of this study was to compare the effects of compound stimuli in discriminated operants (i.e., different combinations of hear, see, touch, and taste) on the acquisition of object-attribute relations, on the emergence of untrained attribute-object relations, and on the acquisition and emergence of same-different relations between objects and their attributes. All the participants were on the autism spectrum and between 4 and 12 years old. Participants who did not meet the mastery criterion or show emergent intraverbal responses during initial training trials completed a fluency-based practice phase. Overall results showed that all six participants required fewer trials to meet the criterion in the condition involving compound stimuli (e.g., HearSeeSay plus Touch, Taste, or Sniff) as compared to the HearSeeSay-alone condition. In addition, participants required fewer fluency practice timings in the condition involving compound stimuli to meet fluency aim.

Relationship between reinforcement rate and response rate in Pavlovian and operant conditioning with compound stimuli in rats.

Harris, Andrew, and Livesey (2012) proposed that response rate (R) to a stimulus (e.g., A) of a compound (e.g., AB) would be directly related to the difference between reinforcement rate (r) during AB and the other stimulus (e.g., B). To explore the extent of this proposal to operant conditioning, three experiments were carried out. Experiment 1 replicated Harris et al. (2012 - Experiment 1) using sucrose as US in Pavlovian conditioning. In Experiment 2 rats pressed a lever under a variable interval schedule in two phases. In Training, responses during a compound stimulus AB100% were reinforced 100%, responses during B50% and C50% 50% and responses during D25%, 25% of the trials. Then, nonreinforced A trials were introduced (Probe). Results from Experiment 2 showed that r controlled the R to AB100%, B50%, C50% and D25% during training and probe, however, were inconclusive about r and R relationship during A. In Experiment 3, responses during A100% were reinforced 100% and during B50% and C50% 50% of the trials (Training). Next, nonreinforced BC trials were presented (Probe). Results from Experiment 3 showed that response rate during BC were similar to A100%, but higher than B50% and C50%, suggesting summation of B50% and C50% reinforcement rates. Overall, the results showed that Harris et al. (2012) proposal extends to discriminative operant relations.

Reading comprehension with the Go/No-Go procedure with compound stimuli.

The present study investigated whether the Go/No-Go procedure with compound stimuli produces emergent relations among dictated words (A), pictures (B), and printed words (C) and the emergence of textual behavior (CD) using a multiple probe design across word sets. Three preschool children were exposed to 4 phases: (1) pretests for BC, CB, and CD relations, (2) pretraining with known stimuli, (3) AB and AC training, and (4) posttests for BC, CB, and CD relations. During AB and AC training, responses to A1B1, A2B2, A1C1, and A2C2 compound stimuli, but not to A1B2, A2B1, A1C2, and A2C1, were reinforced. The results showed that all participants met the learning criterion and demonstrated emergence of BC and CB relations (i.e., relations between pictures and printed words), and CD relations (i.e., textual behavior) after training. These results suggest that the Go/No-Go procedure with compound stimuli is an effective alternative for establishing reading comprehension.

The Global Properties of Objects Play the Main Role in Facilitating Multiple Object Tracking Performance.

Previous research has revealed the uniqueness-facilitation effect in the multiple object tracking (MOT) task: simple distinct identities and surface features of moving targets could facilitate attentional tracking. By adapting compound stimuli, the present study investigated whether the global or local properties played the main role in the uniqueness-facilitation effect in the MOT task. The uniqueness of local properties, of global properties or of both local and global properties were considered. Observers' tracking performance in alternative conditions were compared with that in the homogeneous condition wherein all stimuli have identical local and global properties. Results from two experiments suggest that the global properties played the key role in facilitating tracking. The distinctiveness of local properties can also facilitate tracking with global properties being homogeneous. However, when the stimuli's global properties are distinct from each other-whether the local properties being unique or not-observers' tracking performance can achieve the same level as that in the unitary-uniqueness condition wherein the moving objects were distinct unitary letters. These results revealed a global superiority effect in the MOT task. Finally, the facilitation effects of the global and local properties might depend on the stimulus sparsity. When the compound stimuli had fewer local elements, the uniqueness facilitation effect on tracking decreased.

Children inhibit global information when the forest is dense and local information when the forest is sparse.

Visual environments are composed of global shapes and local details that compete for attentional resources. In adults, the global level is processed more rapidly than the local level, and global information must be inhibited in order to process local information when the local information and global information are in conflict. Compared with adults, children present less of a bias toward global visual information and appear to be more sensitive to the density of local elements that constitute the global level. The current study aimed, for the first time, to investigate the key role of inhibition during global/local processing in children. By including two different conditions of global saliency during a negative priming procedure, the results showed that when the global level was salient (dense hierarchical figures), 7-year-old children and adults needed to inhibit the global level to process the local information. However, when the global level was less salient (sparse hierarchical figures), only children needed to inhibit the local level to process the global information. These results confirm a weaker global bias and the greater impact of saliency in children than in adults. Moreover, the results indicate that, regardless of age, inhibition of the most salient hierarchical level is systematically required to select the less salient but more relevant level. These findings have important implications for future research in this area.

Moderate Partially Reduplicated Conditioned Stimuli as Retrieval Cue Can Increase Effect on Preventing Relapse of Fear to Compound Stimuli.

The theory of memory reconsolidation argues that consolidated memory is not unchangeable. Once a memory is reactivated it may go back into an unstable state and need new protein synthesis to be consolidated again, which is called "memory reconsolidation". Boundary studies have shown that interfering with reconsolidation through pharmacologic or behavioral intervention can lead to the updating of the initial memory, for example, erasing undesired memories. Behavioral procedures based on memory reconsolidation interference have been shown to be an effective way to inhibit fear memory relapse after extinction. However, the effectiveness of retrieval-extinction differs by subtle differences in the protocol of the reactivation session. This represents a challenge with regard to finding an optimal operational model to facilitate its clinical use for patients suffering from pathogenic memories such as those associated with post-traumatic stress disorder. Most of the laboratory models for fear learning have used a single conditioned stimulus (CS) paired with an unconditioned stimulus (US). This has simplified the real situation of traumatic events to an excessive degree, and thus, limits the clinical application of the findings based on these models. Here, we used a basic visual compound CS model as the CS to ascertain whether partial repetition of the compound CSs in conditioning can reactivate memory into reconsolidation. The results showed that the no retrieval group or the 1/3 ratio retrieval group failed to open the memory reconsolidation time window. The 2/3 repetition retrieval group and the whole repetition retrieval group were able to prevent fear reinstatement, whereas only a 2/3 ratio repetition of the initial compound CS as a reminder could inhibit spontaneous recovery. We inferred that a retrieval-extinction paradigm was also effective in a more complex model of fear if a sufficient prediction error (PE) could be generated in the reactivation period. In addition, in order to achieve an optimal effect, a CS of moderate discrepancy should be used as a reminder.

Go/no-go procedure with compound stimuli with children with autism.

The go/no-go with compound stimuli is an alternative to matching-to-sample to produce conditional and emergent relations in adults. The aim of this study was to evaluate the effectiveness of this procedure with two children diagnosed with autism. We trained and tested participants to respond to conditional relations among arbitrary stimuli using the go/no-go procedure. Both learned all the trained conditional relations without developing response bias or responding to no-go trials. Participants demonstrated performance consistent with symmetry, but not equivalence.

Generalization of the disruptive effects of alternative stimuli when combined with target stimuli in extinction.

Differential-reinforcement treatments reduce target problem behavior in the short term but at the expense of making it more persistent long term. Basic and translational research based on behavioral momentum theory suggests that combining features of stimuli governing an alternative response with the stimuli governing target responding could make target responding less persistent. However, changes to the alternative stimulus context when combining alternative and target stimuli could diminish the effectiveness of the alternative stimulus in reducing target responding. In an animal model with pigeons, the present study reinforced responding in the presence of target and alternative stimuli. When combining the alternative and target stimuli during extinction, we altered the alternative stimulus through changes in line orientation. We found that (1) combining alternative and target stimuli in extinction more effectively decreased target responding than presenting the target stimulus on its own; (2) combining these stimuli was more effective in decreasing target responding trained with lower reinforcement rates; and (3) changing the alternative stimulus reduced its effectiveness when it was combined with the target stimulus. Therefore, changing alternative stimuli (e.g., therapist, clinical setting) during behavioral treatments that combine alternative and target stimuli could reduce the effectiveness of those treatments in disrupting problem behavior.

Assessing the role of alternative response rates and reinforcer rates in resistance to extinction of target responding when combining stimuli.

Studies of behavioral momentum reveal that reinforcing an alternative response in the presence of a target response reduces the rate of target responding but increases its persistence, relative to training the target response on its own. Because of the parallels between these studies and differential-reinforcement techniques to reduce problem behavior in clinical settings, alternative techniques to reduce problem behavior without enhancing its persistence are being explored. One potential solution is to train an alternative response in a separate stimulus context from problem behavior before combining the alternative stimulus with the target stimulus. The present study assessed how differences in reinforcement contingencies and rate for alternative responding influenced resistance to extinction of target responding when combining alternative and target stimuli in pigeons. Across three experiments, alternative stimuli signaling a response-reinforcer dependency and greater reinforcer rates more effectively decreased the persistence of target responding when combining alternative and target stimuli within the same extinction tests, but not when compared across separate extinction tests. Overall, these findings reveal that differences in competition between alternative and target responding produced by contingencies of alternative reinforcement could influence the effectiveness of treating problem behavior through combining stimulus contexts.

The effects of listener training on discriminative control by elements of compound stimuli in children with disabilities.

The purpose of the current study was to assess whether the establishment of listener relations with compound stimuli as samples and comparisons would lead to the emergence of: (1) speaker behavior in the form of tacts of the compound stimuli; (2) listener and tact responses for untaught compounds; and (3) listener and tact responses for the isolated properties of compounds. Participants were four boys diagnosed with autism and one diagnosed with intellectual disability. We taught participants to select among three compound comparisons consisting of combinations of shapes and patterns in the presence of the corresponding dictated word. Subsequently, we tested for the emergence of tacts for the trained compounds, as well as tact and listener relations for six untaught compounds and their properties. In general, results showed that the acquisition of listener relations led to the emergence of the corresponding tacts, as well as the emergence of listener and tact responses for untaught combinations for three out of five participants. By contrast, the other two participants showed responding characteristic of restricted stimulus control. These results suggest that the establishment of bidirectional relations between listener and speaker behaviors may facilitate the emergence of control by properties of compound stimuli.

Method of stimulus combination impacts resistance to extinction.

Reinforcing an alternative response in the presence of the stimuli governing a target response increases resistance to extinction of target responding, relative to training target responding on its own. Conversely, training alternative and target responses in the presence of different stimuli and combining those stimuli only decreases resistance to extinction of target responding, relative to target responding on its own. The present study assessed how different methods of combining discriminative stimuli influence resistance to extinction of responding in pigeons. As in previous studies, combining stimuli across different keys only decreased resistance to extinction of target responding relative to target responding on its own. In comparison, combining stimuli on the same key initially increased resistance to extinction of target responding, but repeated tests resulted in similar levels of responding as target responding with stimuli combined on separate keys. Moreover, greater overall reinforcement rates produced greater resistance to extinction with both methods of combining stimuli, consistent with behavioral momentum theory. These findings reveal several behavioral processes influence the outcome of combining stimuli--including perceptual processes, discriminative control by contingencies, response competition, and behavioral momentum.

Contextual control using a go/no-go procedure with compound abstract stimuli.

Contextual control has been described as (1) a five-term contingency, in which the contextual stimulus exerts conditional control over conditional discriminations, and (2) allowing one stimulus to be a member of different equivalence classes without merging them into one. Matching-to-sample is the most commonly employed procedure to produce and study contextual control. The present study evaluated whether the go/no-go procedure with compound stimuli produces equivalence classes that share stimuli. This procedure does not allow the identification of specific stimulus functions (e.g., contextual, conditional, or discriminative functions). If equivalence classes were established with this procedure, then only the latter part of the contextual control definition (2) would be met. Six undergraduate students participated in the present study. In the training phases, responses to AC, BD, and XY compounds with stimuli from the same classes were reinforced, and responses to AC, BD, and XY compounds with stimuli from different classes were not. In addition, responses to X1A1B1, X1A2B2, X2A1B2, and X2A2B1 compounds were reinforced and responses to the other combinations were not. During the tests, the participants had to respond to new combinations of stimuli compounds YCD to indicate the formation of four equivalence classes that share stimuli: X1A1B1Y1C1D1, X1A2B2Y1C2D2, X2A1B2Y2C1D2, and X2A2B1Y2C2D1. Four of the six participants showed the establishment of these classes. These results indicate that establishing contextual stimulus functions is unnecessary to produce equivalence classes that share stimuli. Therefore, these results are inconsistent with the first part of the definition of contextual control.

Stimulus control in a go/no-go procedure with compound stimuli with pigeons.

Our previous study using a go/no-go procedure with compound stimuli taught pigeons to peck at two-component compounds A1B1, A2B2, B1C1, B2C2 and refrain from pecking at A1B2, A2B1, B1C2, B2C1. Subjects showed training-consistent responding in tests presenting compounds rotated 180° (BA and CB relations) but not recombined (AC and CA relations). It is unclear whether the responses to BA and CB stimuli were controlled by the relation between the components (conditional discrimination) or by the compounds functioning as a unitary stimulus (simple discrimination). The present study assessed whether the four pigeons from our previous study would show maintained discrimination when the positions of the components of each compound were changed relative to the training stimuli. Training components were rotated 90° to the right and left (Tests 1 and 2, respectively), presented with a 1cm separation (Test 3), and presented with a 1cm separation and rotated 180° (Test 4). Subject P11 maintained discriminations in all tests. Maintained discriminations were only observed in Tests 1 and 2 for P21, 1-3 for P10, and 1, 2, and 4 for P9. Results indicate that pigeons may not maintain discrimination when stimulus elements are presented further apart and/or rotated 180° relative to training.

Same, same­but different: on the use of Navon derived measures of global/local processing in studies of face processing.

Some studies have reported a significant correlation between face discrimination/recognition ability and indexes of global/local processing derived from the Navon paradigm. Other studies, however, have failed to find such a relationship. In this paper we examine three aspects related to the Navon paradigm that may have contributed to this discrepancy but which have been largely neglected: (i) the use of different types of compound stimuli across studies, (ii) differences between studies in the type of index derived from the Navon paradigm, and (iii) the reliability of these indexes. In a Navon experiment comparing performance with compound letters and compound shapes in normal participants, we find little consistency both within and across participants in how they perform with these stimulus types, despite the fact that both stimulus types give rise to the typical effects. In addition we find that many of the Navon derived indexes of global/local effects used in studies examining face processing have low reliability and do not measure the same aspects of global/local processing. Echoing the results from the normal participants, we also find little consistency in how a congenital prosopagnosic performs in the Navon paradigm. With compound letters, she responds much faster to local than to global aspects of the stimuli; a pattern not seen in a single of the normal participants. With compound shapes, however, she exhibits no such abnormality. These findings question the validity of the conclusions in studies relating Navon derived indexes of global/local processing to face processing.

Assessing restricted stimulus control in typically developing preschool children and bees (Melipona quadrifasciata)

This study established a simple simultaneous discrimination between a pair of two-element compound visual stimuli in children (Experiment 1) and bees (Melipona quadrifasciata, Experiment 2). The contingencies required discriminative control by the compound and the question was whether the accurate stimulus control reached at this level would hold for each individual element of the compound. After baseline reached stability, probe trials assessed stimulus control by each single element of both S+ and S-. Average data showed that children (Exp. 1) tended to show stimulus control by a single element of the S+ compound. In Experiment 2 three of four bees showed stimulus control by both elements of S+ and did not respond or responded only infrequently to the elements of the S-. The children's decline in discrimination accuracy in probe trials, along with its maintenance during the baseline, replicated previous findings showing the development of restricted stimulus control (RSC). The precise stimulus control shown by the bees indicated that all elements correlated with reinforcement acquired stimulus control over their behavior; this confirms the extensive literature on visual discriminative learning in bees, but due to the small number of subjects it is premature to say that bees do not develop RSC...

Assessing restricted stimulus control in typically developing preschool children and bees (Melipona quadrifasciata)

This study established a simple simultaneous discrimination between a pair of two-element compound visual stimuli in children (Experiment 1) and bees (Melipona quadrifasciata, Experiment 2). The contingencies required discriminative control by the compound and the question was whether the accurate stimulus control reached at this level would hold for each individual element of the compound. After baseline reached stability, probe trials assessed stimulus control by each single element of both S+ and S-. Average data showed that children (Exp. 1) tended to show stimulus control by a single element of the S+ compound. In Experiment 2 three of four bees showed stimulus control by both elements of S+ and did not respond or responded only infrequently to the elements of the S-. The children's decline in discrimination accuracy in probe trials, along with its maintenance during the baseline, replicated previous findings showing the development of restricted stimulus control (RSC). The precise stimulus control shown by the bees indicated that all elements correlated with reinforcement acquired stimulus control over their behavior; this confirms the extensive literature on visual discriminative learning in bees, but due to the small number of subjects it is premature to say that bees do not develop RSC.(AU)