The ubiquity of selective attention in the processing of feedback during category learning

Feedback is essential for many kinds of learning, but the cognitive processes involved in learning from feedback are unclear. Models of category learning incorporate selective attention to stimulus features while generating a response, but during the feedback phase of an experiment, it is assumed that participants receive complete information about stimulus features as well as the correct category. The present work looks at eye tracking data from six category learning datasets covering a variety of category complexities and types. We find that selective attention to task-relevant information is pervasive throughout feedback processing, suggesting a role for selective attention in memory encoding of category exemplars. We also find that error trials elicit additional stimulus processing during the feedback phase. Finally, our data reveal that participants increasingly skip the processing of feedback altogether. At the broadest level, these three findings reveal that selective attention is ubiquitous throughout the entire category learning task, functioning to emphasize the importance of certain stimulus features, the helpfulness of extra stimulus encoding during times of uncertainty, and the superfluousness of feedback once one has learned the task. We discuss the implications of our findings for modelling efforts in category learning from the perspective of researchers trying to capture the full dynamic interaction of selective attention and learning, as well as for researchers focused on other issues, such as category representation, whose work only requires simplifications that do a reasonable job of capturing learning.

Contrasting Effects of Plant-Soil Feedbacks on Growth and Morphology of Two Clonal Plants

AimSoil abiotic and biotic conditions are often spatially variable, challenging plants with a heterogeneous environment consisting of favorable and unfavorable patches of soil. Many stoloniferous clonal plants can escape from unfavorable patches by elongating stolon internodes, but aggregate in favorable ones through shortening stolon internodes. However, whether these plants can use their stolons to respond to plant-soil feedbacks (PSFs) is largely unknown. MethodsIn the conditioning phase, we grew either Hydrocotyle vulgaris or Glechoma longituba clonal plants separately in mesocosms to condition bulk soil. In the feedback phase, we grew connected mother and daughter ramets of each species in soil inoculated with the unsterilized or sterilized soil conditioned by conspecifics. We grew the plants for 12 weeks and measured the growth of the mother and daughter ramets separately. ResultsThe daughter ramets of H. vulgaris produced more biomass but shorter stolon internodes when grown in soil with sterilized inocula than with unsterilized inocula. However, no difference was found between the daughter ramets of G. longituba grown in soil with unsterilized and sterilized inocula. For both species, no significant difference was found between the mother ramet or between the daughter ramets when the mother ramet was grown in soil with sterilized and unsterilized inocula. ConclusionsThe daughter ramets rather than the mother ramet of H. vulgaris experienced negative biotic PSFs. However, PSF had no effects on the daughter or mother ramet of G. longituba. Moreover, physiological integration or plasticity in stolon internode lengths cannot help H. vulgaris alleviate the negative PSFs.

Assessing the usefulness of instant feedback and the Hawthorne effect: an audit of time indexes of EMS missions in Tehran

Introduction It has been well established that if a person is aware that they are being monitored their commitment and effort will be maximised (the Hawthorne effect), which then leads to efficiency increase and optimal workflow. Objective Our aim was to evaluate the efficacy of instant feedback and the Hawthorne effect of this intervention on pre-hospital time indexes during emergency medical service (EMS) missions. Methods This is a cross-sectional auditing study on the missions of the Tehran EMS Center (performed over a 12-month period) in three phases: pre-intervention, instant feedback, and monitoring without feedback. The measured time indexes were the different parts of mission times. To collect data, a pre-prepared checklist was set up. For the first phase, data were extracted from the database of the Tehran EMS Center. In the second and third phases, the data were entered into the relevant forms for each mission by the researcher and executive colleagues. Results The data of 229,847 missions were analysed. In the instant feedback phase, compared to the pre-intervention phase, the mean activation time, response time, scene time, transfer time and hospital delay time were decreased. When we compared the mean time indexes in the monitoring phase compared to the instant feedback phase, we saw that the average activation time, response time and transfer time were increased but they were still less than that in the pre-intervention phase. However, the scene time and hospital delay time were not changed compared to the instant feedback phase but were lower than that in the pre-intervention phase. Conclusion Auditing was effective in reducing the total time of missions and this effect was largely maintained in the monitoring phase under the Hawthorne effect.

Direct Biotic Plant–soil Feedback Promotes Dodonaea Viscosa Growth in a Dry-hot Valley, China

Biotic plant-soil feedback has been widely studied, and may be particularly important in resource-poor areas. However, the roles of soil nutrient cycling in affecting plant growth in this process still remained unclear. The aim of this study was to explore the roles of soil biota in regulating nutrient cycling by conducting a two-phase feedback experiment in a dry-hot valley, with a conditioning phase during which there were Dodonaea viscosa or no D. viscosa growing in the soil, and a feedback phase in which the effect of the conditioned soil biota on D. viscosa performance was measured. The growth of D. viscosa significantly reduced soil N after the conditioning phase. However, D. viscosa showed a positive plant-soil feedback. In the feedback phase, the D. viscosa conditioned soil promoted the stem diameter, leaf area, and leaf dry mass content of D. viscosa. Total biomass was also significantly higher in D. viscosa conditioned soil than that in not conditioned soil. In contrast, soil sterilization had a negative effect on the growth of D. viscosa, with a significant reduction in plant biomass, especially in D. viscosa conditioned soil, and soil sterilization significantly increased the root: shoot biomass ratio and litter mass. Furthermore, we showed that although the biota-driven changes in enzyme activities correlated with the leaf N and P amount especially P amount, the enzyme activity was not the main reason to promote D. viscosa growth in the conditioned soil.

Encoding Motivation Prediction Errors in the Human Dopaminergic Reward System

The dopaminergic reward system encoding the reward PE signals is vital for reinforcement learning (RL). Although this reward PE hypothesis has been extensively validated, it remains considerable debates on the alternative account of motivation. In the current study, we diverted the participants’ motivation from the conditioned stimulus (CS)-associated valences to the CS-elicited actions in a variant Pavlovian conditioning task under appetitive and aversive conditions. We found that the regions in the dopaminergic reward system did not encode such bidirectional reward PE signals, but the PE magnitudes, namely, the motivation PE signals. These neural signals without indicating the directions of learning could not be directly used for model-free RL, but probably for model-based control. Specifically, the ventral striatum during the feedback phase might encode the need of adjusting the learning policy, while the putative substantia nigra pars compacta (SNc) in the midbrain and the putamen during the prediction phase might sustain the intended actions. Meanwhile, the primary motor cortex encoded the salience PE signals for model-free RL. Therefore, our findings demonstrate that the human dopaminergic reward system could encode the motivation PE signals to substantialize model-based control, rather than model-free learning, suggesting that its involvement in RL should be motivation-dependent.