Negative Patterning Discrimination Research Articles

Negative patterning in the spatial domain

In three experiments, animals were required to learn about the presence or absence of a hidden platform in a swimming pool. This was determined with reference to different patterned landmarks. In Experiment 1, the presence of a spotted or a striped cue indicated the position of the platform, while the combination of patterns, a half-spotted and half-striped cue, predicted the absence of the goal (i.e., negative patterning). In Experiment 2 the task was redesigned to better represent a locale navigation task. Rats received the same discrimination task, but it took place in an equilateral triangle with landmarks positioned on the walls of the arena. The hidden platform (if present) was located in one corner of the triangle. Experiment 3 used a more complex negative patterning discrimination in the triangular swimming pool to help dissociate between the unique cue and configural associative learning theories. Experiment 1 and 2 provides the first instance of negative patterning in a spatial task, while Experiment 3 provides initial evidence that some rats may represent compound stimuli in a way explained by the unique cue theory of associative learning. This begins to elucidate the underlying of associate principles that guide learning in the spatial domain.

Chromatic, achromatic and bimodal negative patterning discrimination by free-flying bumble bees

Negative patterning discrimination is considered a nonelemental form of learning, and has been extensively investigated across taxa. Several insect species have also been examined with this task, but only honey bees, Apis mellifera , have so far demonstrated this capacity. Recent empirical and theoretical studies suggest that negative patterning can be accounted for by the emergent property of the mushroom body circuitry in the honey bee brain. Given the neurobiological similarity between bumble bees and honey bees, we hypothesized that bumble bees should also have this cognitive capacity. Here we showed that free-flying bumble bees, Bombus terrestris , learned chromatic, achromatic and visual-olfactory bimodal negative patterning discrimination. Further analyses showed that individual bumble bees adopted distinct strategies in approaching negative patterning discrimination, some solving the task in a configural manner, while others solved it via a simpler strategy. Our findings are in contrast to previous work using harnessed bumble bees and highlight the importance of designing experiments around the requirements of specific species. Our results add to our knowledge on insect nonelemental learning and open up new opportunities for examining cognitive limitations and individual decision-making strategies. • Free-flying bumble bees demonstrate a nonelemental form of learning. • Bumble bees can solve colour, visual pattern and visual-olfactory negative patterning. • Bees show interindividual differences in the bimodal negative patterning task.

Higher-order discrimination learning by honeybees in a virtual environment.

Non-elemental learning constitutes a cognitive challenge because events to be learned are usually ambiguous in terms of reinforcement outcome, contrary to elemental learning, which relies on unambiguous associations. Negative patterning (NP) constitutes a paradigmatic case of non-elemental learning, as subjects have to learn that single elements are reinforced while their simultaneous presentation is not reinforced (A+, B+ vs. AB-). Solving NP requires treating AB as being different from the linear sum of its components in order to overcome the ambiguity of stimulus reinforcement (i.e. A and B are as often reinforced as not reinforced). The honeybee is currently the only insect mastering NP as shown by studies restricted mainly to the olfactory domain. Here, we tested the bees' capacity to solve a NP discrimination in the visual domain and used to this end a virtual reality (VR) environment in which a tethered bee walking stationary on a spherical treadmill faces visual stimuli projected on a semicircular screen. We show that bees learn a composite grating made of alternated green and blue bars in an elemental way, and generalize their response to both a blue and a green grating. Yet, after NP training, one-quarter of the bees inhibited elemental processing and responded significantly more to the single-coloured gratings than to the composite grating. Alternative strategies were used by the other bees, which achieved partial NP learning. These results offer attractive perspectives to study different forms of visual learning in a controlled VR environment, and dissect their underlying mechanisms.

Permanent damage or temporary silencing of retrosplenial cortex impairs the expression of a negative patterning discrimination.

The retrosplenial cortex (RSC) is positioned at the interface between cortical sensory regions and the hippocampal/parahippocampal memory system. As such, it has been theorized that RSC may have a fundamental role in linking sensory stimuli together in the service of forming complex representations. To test this, three experiments were carried out to determine the effects of RSC damage or temporary inactivation on learning or performing a negative patterning discrimination. In this procedure, two conditioned stimuli are reinforced when they are presented individually (i.e., stimulus elements) but are non-reinforced when they are presented simultaneously as a compound stimulus. Normal rats successfully discriminate between the two types of trials as evidenced by more responding to the elements compared to the compound stimulus. This is thought to reflect the formation of a configural representation of the compound stimulus; that is, the two cues are linked together in such a fashion that the compound stimulus is a wholly different, unique stimulus. Permanent lesions of RSC made prior to training (Experiment 1) had no effect on learning the discrimination. However, lesions (Experiment 2) or temporary chemogenetic inactivation (Experiment 3) of RSC made after training impaired subsequent performance of the discrimination. We argue that this pattern of results indicates that RSC may normally be involved in forming the configural representations manifested in negative patterning, but that absent the RSC, other brain systems or structures can compensate sufficiently to result in normal behavior.

When is the rat retrosplenial cortex required for stimulus integration?

The rodent retrosplenial cortex is known to be vital for spatial cognition, but evidence has also pointed to a role in processing nonspatial information. It has been suggested that the retrosplenial cortex may serve as a site of integration of incoming sensory information. To examine this proposal, the current set of experiments assessed the impact of excitotoxic lesions in the retrosplenial cortex on two behavioral tasks that tax animals’ ability to process multiple and overlapping environmental stimuli. In Experiment 1, rats with retrosplenial lesions acquired a negative patterning discrimination, a form of configural learning that can be solved only by learning the conjunction of cues. Subsequent transfer tests confirmed that both the lesion and control animals had solved the task by using configural representations. Furthermore, in Experiment 2, a 2nd cohort of retrosplenial lesion animals successfully acquired conditioned inhibition. Nevertheless, the same animals failed a subsequent summation test that assesses the ability to transfer what has been learned about one stimulus to another stimulus in the absence of reinforcement. Taken together, these results suggest that in the nonspatial domain, the retrosplenial cortex is not required for forming associations between multiple or overlapping environmental stimuli and, consequently, retrosplenial engagement in such processes is more selective than was previously envisaged.

Bimodal Patterning Discrimination in Harnessed Honey Bees

In natural environments, stimuli and events learned by animals usually occur in a combination of more than one sensory modality. An important problem in experimental psychology has been thus to understand how organisms learn about multimodal compounds and how they discriminate this compounds from their unimodal constituents. Here we tested the ability of honey bees to learn bimodal patterning discriminations in which a visual-olfactory compound (AB) should be differentiated from its visual (A) and olfactory (B) elements. We found that harnessed bees trained in classical conditioning of the proboscis extension reflex (PER) are able to solve bimodal positive and negative patterning (NP) tasks. In positive patterning (PP), bees learned to respond significantly more to a bimodal reinforced compound (AB+) than to non-reinforced presentations of single visual (A-) or olfactory (B-) elements. In NP, bees learned to suppress their responses to a non-reinforced compound (AB-) and increase their responses to reinforced presentations of visual (A+) or olfactory (B+) elements alone. We compared the effect of two different inter-trial intervals (ITI) in our conditioning approaches. Whereas an ITI of 8 min allowed solving both PP and NP, only PP could be solved with a shorter ITI of 3 min. In all successful cases of bimodal PP and NP, bees were still able to discriminate between reinforced and non-reinforced stimuli in memory tests performed one hour after conditioning. The analysis of individual performances in PP and NP revealed that different learning strategies emerged in distinct individuals. Both in PP and NP, high levels of generalization were found between elements and compound at the individual level, suggesting a similar difficulty for bees to solve these bimodal patterning tasks. We discuss our results in light of elemental and configural learning theories that may support the strategies adopted by honey bees to solve bimodal PP or NP discriminations.

On the representation of novel stimuli in patterning and irrelevant cue discriminations.

Two experiments explored ways in which novel stimuli might be represented in associative learning, focusing on (1) representations in which novel stimuli embody novelty as a stimulus feature that acquires associative strength in the same fashion as color, shape, texture, or other frequently used stimulus features; and (2) representations in which novel stimuli embody common elements, that is, the stimulus elements shared among other stimuli in an experimental setting. Both experiments examined the effects of reinforcing or nonreinforcing separately presented novel stimuli on learning about compound stimuli that included novel stimuli as part of the compound. Experiment 1 found that the relative ease of learning positive and negative patterning discriminations could be reversed, depending on whether novel stimuli were separately reinforced or nonreinforced. This result is consistent with predictions from a model that assumes novelty is a stimulus feature. Experiment 2 found that the additive effects of combining relevant and irrelevant cues in compound were not obtained when novel stimuli were used as irrelevant cues. This result is consistent with predictions from a model that assumes novel stimuli are represented as common elements. Implications for understanding how both types of representation account for the role of novelty in complex discrimination learning in general are discussed. (PsycINFO Database Record

Summation effects in human learning: evidence from patterning discriminations in goal-tracking.

Participants in two human goal-tracking experiments were simultaneously trained with negative patterning (NP) and positive patterning (PP) discriminations (A+, B+, AB-, C-, D-, CD+). Both elemental and configural models of associative learning predict a PP advantage, such that NP is solved less readily than PP. However, elemental models like the unique cue approach additionally predict responding in AB- trials to be initially stronger than that in A+ and B+ trials due to summation of associative strength. Both experiments revealed a PP advantage and a strong summation effect in AB- trials in the first half of the experiments, irrespective of whether the same US was used for both discriminations (Experiment 1) or two different USs (Experiment 2). We discuss that the correct predictions of the unique cue approach are based on its assumptions of non-normalized and context-independent stimulus processing rather than elemental processing per se.

A Simple Computational Model of the Bee Mushroom Body Can Explain Seemingly Complex Forms of Olfactory Learning and Memory

Honeybees are models for studying how animals with relatively small brains accomplish complex cognition, displaying seemingly advanced (or "non-elemental") learning phenomena involving multiple conditioned stimuli. These include "peak shift" [1-4]-where animals not only respond to entrained stimuli, but respond even more strongly to similar ones that are farther away from non-rewarding stimuli. Bees also display negative and positive patterning discrimination [5], responding in opposite ways to mixtures of two odors than to individual odors. Since Pavlov, it has often been assumed that such phenomena are more complex than simple associate learning. We present a model of connections between olfactory sensory input and bees' mushroom bodies [6], incorporating empirically determined properties of mushroom body circuitry (random connectivity [7], sparse coding [8], and synaptic plasticity [9, 10]). We chose not to optimize the model's parameters to replicate specific behavioral phenomena, because we were interested in the emergent cognitive capacities that would pop out of a network constructed solely based on empirical neuroscientific information and plausible assumptions for unknown parameters. We demonstrate that the circuitry mediating "simple" associative learning can also replicate the various non-elemental forms of learning mentioned above and can effectively multi-task by replicating a range of different learning feats. We found that PN-KC synaptic plasticity is crucial in controlling the generalization-discrimination trade-off-it facilitates peak shift and hinders patterning discrimination-and that PN-to-KC connection number can affect this trade-off. These findings question the notion that forms of learning that have been regarded as "higher order" are computationally more complex than "simple" associative learning.

Learning history and cholinergic modulation in the dorsal hippocampus are necessary for rats to infer the status of a hidden event.

Identifying statistical patterns between environmental stimuli enables organisms to respond adaptively when cues are later observed. However, stimuli are often obscured from detection, necessitating behavior under conditions of ambiguity. Considerable evidence indicates decisions under ambiguity rely on inference processes that draw on past experiences to generate predictions under novel conditions. Despite the high demand for this process and the observation that it deteriorates disproportionately with age, the underlying mechanisms remain unknown. We developed a rodent model of decision-making during ambiguity to examine features of experience that contribute to inference. Rats learned either a simple (positive patterning) or complex (negative patterning) instrumental discrimination between the illumination of one or two lights. During test, only one light was lit while the other relevant light was blocked from physical detection (covered by an opaque shield, rendering its status ambiguous). We found experience with the complex negative patterning discrimination was necessary for rats to behave sensitively to the ambiguous test situation. These rats behaved as if they inferred the presence of the hidden light, responding differently than when the light was explicitly absent (uncovered and unlit). Differential expression profiles of the immediate early gene cFos indicated hippocampal involvement in the inference process while localized microinfusions of the muscarinic antagonist, scopolamine, into the dorsal hippocampus caused rats to behave as if only one light was present. That is, blocking cholinergic modulation prevented the rat from inferring the presence of the hidden light. Collectively, these results suggest cholinergic modulation mediates recruitment of hippocampal processes related to past experiences and transfer of these processes to make decisions during ambiguous situations. Our results correspond with correlations observed between human brain function and inference abilities, suggesting our experiments may inform interventions to alleviate or prevent cognitive dysfunction. © 2015 Wiley Periodicals, Inc.

When patterning discriminations are harder than biconditional ones: A cue constellation approach.

Recent attempts to distinguish configural from nonconfigural accounts of causal learning have compared the relative ease of learning 2 kinds of complex discriminations, a biconditional discrimination (e.g., AB+, CD+, AC0, and BD0), and a negative patterning discrimination, (e.g., A+, B+, and AB0), but have yielded conflicting results. Some studies have found the biconditional task to be easier than negative patterning and others have found negative patterning to be easier than the biconditional. This article evaluates these complex discriminations in several studies using a method that attempts to correct methodological problems that arise in comparisons of individual stimuli and stimulus compounds. Across several variations in procedure, negative patterning discriminations were significantly more difficult than biconditional discriminations. The research also found evidence in comparisons across studies that the difficulty of the biconditional, relative to a comparable nonconfigural compound discrimination, depended on whether the task emphasized configural or nonconfigural cues. The overall pattern of results appeared to be well accounted for by models that include configural information, suggesting that theories which invoke configural elements as a basis for learning complex discriminations remain viable explanatory frameworks.

Sampling capacity underlies individual differences in human associative learning.

Though much work has studied how external factors, such as stimulus properties, influence generalization of associative strength, there has been limited exploration of the influence that internal dispositions may contribute to stimulus processing. Here we report 2 studies using a modified negative patterning discrimination to test the relationship between global processing and generalization. Global processing was associated with stronger negative patterning discrimination, indicative of limited generalization between distinct stimulus compounds and their constituent elements. In Experiment 2, participants pretrained to adopt global processing similarly showed strong negative patterning discrimination. These results demonstrate considerable individual difference in capacity to engage in negative patterning discrimination and suggest that the tendency toward global processing may be one factor explaining this variability. The need for models of learning to account for this variability in learning is discussed.

The decline in rat hippocampal theta activity during response inhibition for the compound stimulus of negative patterning and simultaneous feature-negative tasks

In experiment 1 of this study, we compared hippocampal theta activity between negative patterning and simple discrimination tasks. Our results demonstrated a transient decline in theta activity during response inhibition for a compound stimulus in the negative patterning task. In experiment 2 of this study, we compared hippocampal theta activity among simultaneous feature-negative, compound stimulus discrimination, and simple discrimination tasks in order to determine the cause of the decline in hippocampal theta activity during negative patterning tasks. Our results revealed that the decline in hippocampal theta activity occurred during the response inhibition for a compound stimulus in the simultaneous feature-negative task but not during the compound stimulus discrimination or simple discrimination tasks. Thus, we conclude that the transient decline in hippocampal theta activity is related to the inhibition in response to a compound stimulus that has an element that overlaps with a single stimulus.

Negative Patterning and Biconditional Discriminations in Human Causal Reasoning: A Second Look

Harris and Livesey (2008) reported that patterning discriminations were easier to learn than biconditional discriminations in a human causal reasoning task, consistent with the predictions of the attentional buffer model of Harris (2006) and inconsistent with the predictions of configural cue models. However, their evaluation of patterning and biconditional tasks also failed to find a positive patterning advantage, which has been a hallmark prediction of many configural cue theories. This failure raises the question of whether Harris and Livesey's method was appropriate for a general evaluation of the role of configural cues in learning complex discriminations. Using a design that does produce a positive patterning advantage, the study reported here shows negative patterning discriminations to be at least as difficult to learn as biconditional discriminations, consistent with configural cue models.

Hippocampal theta wave activity during configural and non-configural tasks in rats

This study examined hippocampal theta power during configural and non-configural tasks in rats. Experiment 1 compared hippocampal theta power during a negative patterning task (A+, B+, AB-) to a configural task and a simple discrimination task (A+, B-) as a non-configural task. The results showed that hippocampal theta power during the non-reinforcement trial (non-RFT) of the negative patterning task was higher than that during the simple discrimination task. However, this hippocampal power may reflect sensory processing for compound stimuli that have cross-modality features (the non-RFT of the negative patterning task was presented together with visual and auditory stimuli, but the non-RFT of the simple discrimination task was presented with visual or auditory stimulus alone). Thus, in experiment 2, we examined whether the experiment 1 results were attributable to sensory processing of a compound stimulus by comparing hippocampal theta power during negative patterning (A+, B+, AB-), simultaneous feature-negative (A+, AB-), and simple discrimination tasks (A+, B-). Experiment 2 showed that hippocampal theta activity during the non-RFT in the negative patterning task was higher than that in the simultaneous feature-negative and simple discrimination tasks. Thus, we showed that hippocampal theta activity increased during configural tasks but not during non-configural tasks.

Common elements enhance or retard negative patterning discrimination learning depending on modality of stimuli

Human contingency learning studies were used to compare the predictions of configural and elemental theories. In two experiments, participants were required to learn which stimuli were associated with an increase in core temperature of a fictitious nuclear plant. Experiments investigated the rate at which a simple negative patterning discrimination (A+ B+ ABø) was learned compared to one containing a common but irrelevant element (CD+ CE+ CDEø). When the three elements were from separate modalities (visual, auditory and tactile) the common element enhanced the rate at which the discrimination was learned. When stimuli were drawn from a single modality (visual) the common element disrupted learning. A single elemental model, Harris and Livesey's (2010) attention modulated associative network, was shown to predict both sets of results as the model predicts elements from the same modality attenuate summation. In Experiment 2, the common element was separately paired with a consistent outcome (Cø) and the effect of the common element within the discrimination was found to be removed, again in line with the predictions of Harris and Livesey (2010).

Erratum to: Changes in attention to an irrelevant cue that accompanies a negative patterning discrimination

Erratum to: Changes in attention to an irrelevant cue that accompanies a negative patterning discrimination

Comparing positive and negative patterning in human learning

In human causal learning, positive patterning (PP) and negative patterning (NP) discriminations are often acquired at roughly the same rate, whereas PP is learned faster than NP in most experiments with nonhuman animals. One likely reason for this discrepancy is that most causal learning scenarios encourage participants to treat the presentation and omission of the relevant outcome as two events of comparable significance and likelihood. To investigate this, the current experiments compared PP and NP using a predictive learning paradigm based on a mock gambling task. In Experiment 1, one outcome (winning) was made more salient by being less frequent than the alternative outcome (losing). Under these circumstances, PP was learned faster than NP. In Experiment 2, subjects learned two PP and two NP discriminations, one involved win versus no change outcomes, the other involved lose versus no change outcomes. The subjects learned PP faster than NP, but only when discriminating win from no change. We argue that a difference in difficulty between PP and NP relies on a difference in the salience of the outcomes, consistent with the predictions of a relatively simple model of associative learning.

Changes in attention to an irrelevant cue that accompanies a negative attending discrimination

Pigeons were trained in two experiments with negative patterning discriminations that were accompanied by an irrelevant cue. For Experiment1, the discriminations were of the form AX+ BX+ ABX-, where A and B were relevant, X was irrelevant, and + or - indicate whether or not reinforcement was delivered. The discriminations for Experiment2 were of the form A+ B+ AX+ BX+ ABX-. A subsequent test phase in both experiments revealed that the associability of A and B, and hence the attention paid to these stimuli, was less than the associability of X. The results are explained with a modified version of a configural theory of associative learning.

Elemental and Configural Processes in Patterning Discrimination Learning

Three experiments used appetitive conditioning with rats to examine the involvement of elemental and configural processes in positive and negative patterning discriminations. The first experiment demonstrated that negative and, to some extent, positive patterning discriminations were learned more rapidly when these discriminations consisted of stimulus elements that had previously been the reinforced as opposed to the non-reinforced elements of a simple discrimination. Experiment 2 revealed an excitatory summation effect during the early phase of negative patterning learning that depended upon discrimination pretraining. The final experiment demonstrated faster discrimination learning between the compound and the less salient, rather than the more salient, element of an instrumental patterning task. The present set of results were interpreted as reflecting the possibility, consistent with connectionist theory, that internal representations of the conditioned stimuli change over the course of a patterning ...