Media influence on public policy in Kenya

Many scholars argue that the media can influence policymakers – determining the policy agenda, framing issues, prioritising issues and, on occasion, setting the policy as well. It could be, however, that skilled policymakers exploit the media, so that the media in fact reflects the issues that policymakers want debated. This then poses an important question of whether the media does indeed influence the public policy process. The topic of media influence is widely studied in consolidated democracies but there has been limited research in consolidating democracies. This paper addresses both of these gaps – through exploring the extent to which the media influences policymakers in Kenya, a country perceived to have a moderately free press and one in which a range of interest groups vie to influence government and thus with a media likely to carry a range of competing opinions.

EXPRESS: Inhibitory causal structures in serial and simultaneous feature negative learning

We have previously reported that human participants trained with a simultaneous feature negative discrimination (intermixed A+ / AB- trials) show only modest transfer of inhibitory properties of the feature B to a separately trained excitor in a summation test (Lee & Lovibond, 2021). Self-reported causal structure suggested that many participants learned that the effect of the feature B was somewhat specific to the excitor it had been trained with (modulation), rather than learning that the feature prevented the outcome (prevention). This pattern is reminiscent of the distinction between negative occasion-setting and conditioned inhibition in the animal conditioning literature. However, in animals, occasion-setting is more commonly seen with a serial procedure in which the feature (B) precedes the training excitor (A). Accordingly, we ran three experiments to compare serial with simultaneous training in an allergist causal judgment task. Transfer in a summation test was stronger to a previously modulated test excitor compared to a simple excitor after both simultaneous and serial training. There was a numerical trend towards a larger effect in the serial group, but it failed to reach significance and the Bayes Factor indicated support for the null. Serial training had no differential effect on self-reported causal structure, and did not significantly reduce overall transfer. After both simultaneous and serial training, transfer was strongest in participants who reported a prevention structure, replicating and extending our previous results to a previously modulated excitor. These results suggest that serial feature negative training does not promote a qualitatively different inhibitory causal structure compared to simultaneous training in humans.

Ambiguity Drives Higher-Order Pavlovian Learning

In the natural world, stimulus-outcome associations are often noisy and ambiguous. Learning to disambiguate these associations to identify which specific outcomes will occur is critical for survival. Pavlovian occasion setters are stimuli that determine whether other stimuli that are ambiguous will result in a specific outcome. Occasion setting is a well-established field, but very little investigation has been conducted on how occasion setters are disambiguated when they themselves are ambiguous. We investigated the role of higher-order Pavlovian occasion setting in humans. We also developed and tested the first computational model predicting direct associations, traditional occasion setting, and 2nd-order occasion setting. Results showed that occasion setters affected ambiguous but not unambiguous lower-order stimuli and that 2nd-order occasion setting was indeed learned. Our computational model demonstrated excellent fit with the data, advancing our theoretical understanding of learning with ambiguity. These results may ultimately improve treatment of Pavlovian-based mental health disorders (e.g., anxiety).

Individual differences in causal structures inferred during feature negative learning

Traditional associative learning theories predict that training with feature negative (A+/AB-) contingencies leads to the feature B acquiring negative associative strength and becoming a conditioned inhibitor (i.e., prevention learning). However, feature negative training can sometimes result in negative occasion setting, where B modulates the effect of A. Other studies suggest that participants learn about configurations of cues rather than their individual elements. In this study, we administered simultaneous feature negative training to participants in an allergist causal learning task and tested whether evidence for these three types of learning (prevention, modulation, configural) could be captured via self-report in the absence of any procedural manipulation. Across two experiments, we show that only a small subset of participants endorse the prevention option, suggesting that traditional associative models that predict conditioned inhibition do not completely capture how humans learn about negative contingencies. We also show that the degree of transfer in a summation test corresponds to the implied causal structure underlying conditioned inhibition, occasion-setting, and configural learning, and that participants are only partially sensitive to explicit hints about causal structure. We conclude that feature negative training is an ambiguous causal scenario that reveals individual differences in the representation of inhibitory associations, potentially explaining the modest group-level inhibitory effects often found in humans.

Occasion Setting, Anxiety, and Their Computation in Human Fear Conditioning

Contexts and discrete stimuli often influence the association between a stimulus and outcome. This phenomenon, called occasion setting, is central to the development and modulation of fear. We conducted a human fear conditioning study of Pavlovian occasion setting using traditional methodology and investigated the effects of trait anxiety on fear. We predicted that if occasion setting is based on modulating danger/safety of an ambiguous stimulus, then trait anxiety should be associated with greater fear of ambiguous occasion-setting-based stimuli. We additionally present a novel computational model predicting occasion setting, which calculates occasion setting based on prediction error and quantifying learned stimulus ambiguity. Results show that participants were able to successfully learn which stimuli predicted danger and safety across all stimuli. Additionally, individuals high in trait anxiety generally showed increases in fear in occasion setting conditions. Furthermore, our computational model showed excellent model fit. These results are highly relevant for our understanding and treatment of anxiety disorders.

Occasion setters determine responses of putative dopamine neurons to discriminative stimuli

Midbrain dopamine (DA) neurons are involved in the processing of rewards and reward-predicting stimuli, possibly analogous to reinforcement learning reward prediction errors. Here we studied the activity of putative DA neurons (n=41) recorded in the ventral tegmental area of rats (n=6) performing a behavioural task involving occasion setting. In this task an occasion setter (OS) indicated that the relationship between a discriminative stimulus (DS) and reinforcement is in effect, so that reinforcement of bar pressing occurred only after the OS (tone or houselight) was followed by the DS (houselight or tone). We found that responses of putative DA cells to the DS were enhanced when preceded by the OS, as were behavioural responses to obtain rewards. Surprisingly though, we did not find a population response of putative DA neurons to the OS, contrary to predictions of standard temporal-difference models of DA neurons. However, despite the absence of a population response, putative DA neurons exhibited a heterogeneous response on a single unit level, so that some units increased and others decreased their activity as a response to the OS. Similarly, putative non-DA cells did not respond to the DS on a population level, but with heterogeneous responses on a single unit level. The heterogeneity in the responses of putative DA cells may reflect how DA neurons encode context and point to local differences in DA signalling.

Stable Individual Differences in Occasion Setting

In the current investigation, we classified participants as inhibitors or non-inhibitors depending on the extent to which they showed conditioned inhibition in a context that had been used for extinction of a conditioned response. This classification enabled us to predict participant responses in a second experiment which used a different design and a different experimental task. In the second experiment a feature-negative discrimination survived reversal training of the feature to a greater extent in the non-inhibitors than in the inhibitors and this result was supported by Bayesian analyses. We propose that the fundamental distinction between inhibitors and non-inhibitors is based on a tendency to utilize first-order (direct associations) or second-order (occasion-setting) strategies when faced with ambiguous information and that this classification is a stable individual differences attribute.