Individual differences in proactive interference in rats (Rattus Norvegicus)

Individual differences in behaviors are seen across many species, and investigations have focused on traits linked to aggression, risk taking, emotionality, coping styles, and differences in cognitive systems. The current study investigated whether there were individual differences in proactive interference tasks in rats (Rattus Norvegicus), and tested hypotheses suggesting that these tasks should load onto a single factor and there should be clusters of rats who perform well or poorly on these tasks. The performance of 39 rats was tested across three learning tasks that all involved disengagement from an irrelevant previously learned stimulus to a relevant stimulus: latent inhibition (LI), partial reinforcement extinction effect (PREE), and reversal learning (RL). An exploratory factor analysis revealed the existence of one factor underlying performance. A cluster analysis revealed the existence of sets of rats displaying either weak LI and strong PREE and RL effects, or vice versa. These findings suggest that proactive interference may be based on a single underlying psychological system in rats.

Señales de amenaza y sesgo atencional en lafobia a la sangre, inyecciones y heridasy en la fobia a las serpientes

El objetivo de esta investigación fue estudiar el efecto de una señal que indica la aparición de una imagen fóbica sobre la actividad electrocortical provocada por el estímulo relevante para el trastorno en la fobia a la sangre por lesión en inyección (BII) y la fobia a las serpientes. Una muestra de 13 participantes con fobia BII, 12 individuos con fobia a las serpientes y 14 controles no fóbicos se sometieron a una tarea S1-S2, donde S1 era una palabra que describía el contenido de una imagen posterior (relacionada con la sangre, serpiente y neutral) que apareció 2 segundos después (S2). Obtuvimos las amplitudes ERP P200 y P300 provocadas por las imágenes. Nuestros resultados revelan que P200 no diferenciaba entre el contenido de las imágenes en la fobia BII mientras que, por el contrario, las imágenes relacionadas con la serpiente y la sangre provocaron las respuestas más grandes en los participantes con fobia a las serpientes. Tanto las imágenes relacionadas con la sangre como las de serpientes provocaron amplitudes de P300 mayores que las imágenes neutrales en todos los grupos. Las señales de amenaza redujeron la reacción electrocortical del BII, posiblemente por la provocación de respuestas anticipatorias o reguladoras. Estos resultados son indicativos de una baja atención automática exógena hacia los estímulos temidos en la fobia BII, como lo revela P200, probablemente relacionado con una falta de sesgo de atención al objeto fóbico. The aim of this research was to study the effect of a cue signalling the upcoming of a phobic picture on the electrocortical activity provoked by the disorder-relevant stimulus in in blood-injection-injury (BII) phobia and snake phobia. A sample of 13 BII phobia participants, 12 snake phobia individuals and 14 non-phobic controls underwent an S1-S2 task, where S1 was a word that described the content of a subsequent picture (blood-related, snake and neutral) that appeared 2 seconds later (S2). We obtained the P200 and P300 ERP amplitudes provoked by the pictures. Our results reveal that P200 did not differentiate between picture contents in BII phobia while, in contrast, snake and blood-related pictures provoked the largest responses in snake phobia participants. Both blood-related and snake pictures provoked greater P300 amplitudes than neutral pictures in all the groups. Threat cues reduced the electrocortical reaction of the BII, possibly by the elicitation of anticipatory or regulatory responses. These results are indicative of a low automatic, exogenous attention towards the feared stimuli in BII phobia, as revealed by P200, probably related to a lack of attentional bias to the phobic object.

Face Perception and Pareidolia Production in Patients With Parkinson's Disease

In Parkinson's disease (PD) patients, visual misperceptions are a major problem within the non-motor symptoms. Pareidolia, i.e., the tendency to perceive a specific, meaningful image in an ambiguous visual pattern, is a phenomenon that occurs also in healthy subjects. Literature suggests that the perception of face pareidolia may be increased in patients with neurodegenerative diseases. We aimed to examine, within the same experiment, face perception and the production of face pareidolia in PD patients and healthy controls (HC). Thirty participants (15 PD patients and 15 HC) were presented with 47 naturalistic photographs in which faces were embedded or not. The likelihood to perceive the embedded faces was modified by manipulating their transparency. Participants were asked to decide for each photograph whether a face was embedded or not. We found that PD patients were significantly less likely to recognize embedded faces than controls. However, PD patients also perceived faces significantly more often in locations where none were actually present than controls. Linear regression analyses showed that gender, age, hallucinations, and Multiple-Choice Vocabulary Intelligence Test (MWT) score were significant predictors of face pareidolia production in PD patients. Montreal Cognitive Assessment (MoCA) was a significant predictor for pareidolia production in PD patients in trials in which a face was embedded in another region [F(1, 13) = 24.4, p = <0.001]. We conclude that our new embedded faces paradigm is a useful tool to distinguish face perception performance between HC and PD patients. Furthermore, we speculate that our results observed in PD patients rely on disturbed interactions between the Dorsal (DAN) and Ventral Attention Networks (VAN). In photographs in which a face is present, the VAN may detect this as a behaviourally relevant stimulus. However, due to the deficient communication with the DAN in PD patients, the DAN would not direct attention to the correct location, identifying a face at a location where actually none is present.

Sensory computations in the cuneate nucleus of macaques

In primates, the responses of individual neurons in primary somatosensory cortex (S1) reflect convergent input from multiple classes of nerve fibers and are selective for behaviorally relevant stimulus features. The conventional view is that these response properties reflect computations that are effected in cortex, implying that sensory signals are not meaningfully processed in the two intervening structures - the Cuneate Nucleus (CN) and the thalamus. To test this hypothesis, we recorded the responses evoked in CN to a battery of stimuli that have been extensively used to characterize tactile coding, including skin indentations, vibrations, random dot patterns, and scanned edges. We found that CN responses are more similar to their S1 counterparts than they are to their inputs: CN neurons receive input from multiple sub-modalities, have spatially complex receptive fields, and exhibit selectivity for geometric features. Thus, CN plays a key role in the processing of tactile information.

Naturalistic Audiovisual Stimulation Reveals the Topographic Organization of Human Auditory Cortex

Despite the importance of audition in spatial, semantic, and social function, there is no consensus regarding the detailed organisation of human auditory cortex. Using a novel computational model to analyse a high-powered naturalistic audiovisual movie-watching dataset, we simultaneously estimate spectral tuning properties and category selectivity to reveal the modes of organisation and computational motifs that characterise human auditory cortex. We find that regions more remote from the auditory core exhibit more compressive, non-linear response properties and finely-tuned, speech-selective receptive fields in low frequency portions of the tonotopic map. These patterns of organisation mirror aspects of the visual cortical hierarchy, wherein tuning properties progress from a stimulus category-agnostic front end towards more advanced regions increasingly optimised for behaviorally relevant stimulus categories.

When unsupervised training benefits category learning

Humans continuously categorise inputs, but only rarely receive explicit feedback as to whether or not they are correct. This implies that they may be integrating unsupervised information together with their sparse supervised data -- a form of semi-supervised learning. However, experiments testing semi-supervised learning are rare, and are bedevilled with conflicting results about whether the unsupervised information affords any benefit. Here, we suggest that one important factor that has been paid insufficient attention is the alignment between subjects' internal representations of the stimulus material and the experimenter-defined representations that determine success in the tasks. Subjects' representations are shaped by prior biases and experience, and unsupervised learning can only be successful if the alignment suffices. Otherwise, unsupervised learning might harmfully strengthen incorrect assumptions. To test this hypothesis, we conducted an experiment in which subjects initially categorise items along a salient, but task-irrelevant, dimension, and only recover the correct categories when sufficient feedback draws their attention to the subtle, task-relevant, stimulus dimensions. By withdrawing feedback at different stages along this learning curve, we tested whether unsupervised learning improves or worsens performance when internal stimulus representations and task are sufficiently or insufficiently aligned, respectively. Our results demonstrate that unsupervised learning can indeed have opposing effects on subjects' learning. We also discuss factors limiting the degree to which such effects can be predicted from momentary performance. Our work implies that predicting and understanding human category learning in particular tasks requires assessment and consideration of the representational spaces that subjects entertain for the materials involved in those tasks. These considerations not only apply to studies in the lab, but could also help improve the design of tutoring systems and instruction.

How do consumers respond to price gaps in private brand agrifood products?

PurposeThere is a range around reference prices, the so-called latitude of price acceptance, where consumers seem insensitive to changes into prices, with these ranges being wider for buyers of private brands. This paper analyses objective price gap between two product alternatives as a main driver of consumer behaviour. Therefore, the authors shed light on whether the price gap conditions consumer-switching behaviour and at what point the price gap triggers a switching pattern.Design/methodology/approachShopping data on two product alternatives of olive oil were obtained from a household scanner panel of Spanish consumers (607 households) with weekly price tracking, and multilevel regression models were performed.FindingsThe results suggest that the price gap has a fundamental effect on the consumers' choice. In this case, up to 1 euro/litre the demand seems almost inelastic; beyond that price gap, the demand for the finer product plummets.Research limitations/implicationsThis study focussed on olive oil products. The research needs to be extended other food products.Originality/valueThe authors contribute to the literature by documenting how the price context measured in terms of a price gap is a relevant stimulus in consumer choices, with a focus on the change in price sensitivity between product alternatives when competing brands are not involved but private brands are.

Male attention allocation depends on social context

Attention, although limited, is a mechanism used to filter large amounts of information and determine what stimuli are most relevant at a particular moment. In dynamic social environments, multiple individuals may play a pivotal role in any given interaction where a male’s attention may be divided between a rival, a current mate, and/or future potential mates. Here, we investigated impacts of the social environment on attention allocation in male sailfin mollies, Poecilia latipinna, which are a part of a sexual-unisexual mating system with the Amazon molly, Poecilia formosa. We asked: 1) Does the species of female influence the amount of attention a male allocates to her? And 2) Is a male’s attention towards his mate influenced by different social partners? Males direct more attention toward a stimulus female when she was a conspecific. We also show that males perceive a larger male as a more relevant stimulus to pay attention to than a smaller male, and a conspecific female as a more relevant stimulus compared to a heterospecific female. Our results show differential allocation of attention is dependent upon multiple components of the social environment in which an individual interacts.SignificanceThis study investigates how attention is allocated in males when presented with social distractions. Assuming that attentional capacity is finite, males may face a tradeoff between different cognitive-demanding stimuli, such as rival males and potential future mates, when mating. Here, we show that male attention allocation in both intra- and intersexual interactions is multifaceted and context dependent. This suggests that individuals within the social environment vary in how meaningful (i.e., able to capture attention) they are to males during mating encounters. Understanding how social partners can cause a shift of attention away from a mating opportunity is essential to understanding the influence of the social context on sexual selection.

A Study on Human Learning Ability during Classification of Motion and Colour Visual Cues and Their Combination

The paper presents a study on the human learning process during the classification of stimuli, defined by motion and color visual cues and their combination. Because the classification dimension and the features that define each category are uncertain, we model the learning curves using Bayesian inference and more precisely the Normalized Conjunctive Consensus rule, and also on the base of the more efficient probabilistic Proportional Conflict Redistribution rule No 5 (pPCR5) defined within Dezert-Smarandache Theory (DSmT) of plausible and paradoxical reasoning. Our goal is to study how these rules succeed to model consistently both: human individual and group behaviour during the learning of the associations between the stimuli and the responses in categorization tasks varying by the amount of relevant stimulus information. The effect of age on this process is also evaluated.

Dogs display owner-specific expectations based on olfaction

Most current knowledge about dogs’ understanding of, and reacting to, their environment is limited to the visual or auditory modality, but it remains unclear how olfaction and cognition are linked together. Here we investigate how domestic dogs search for their owners using their excellent olfactory sense. We raise the question whether dogs have a representation of someone when they smell their track. The question is what they expect when they follow a trail or whether they perceive an odour as a relevant or non-relevant stimulus. We adopted a classical violation-of-expectation paradigm—and as targets we used two persons that were both important to the dog, usually the owners. In the critical condition subjects could track the odour trail of one target, but at the end of the trail they find another target. Dogs showed an increased activity when the person did not correspond with the trail compared to a control condition. Moreover, we found huge individual differences in searching behaviour supporting the assumption that dogs are only able to smell when they really sniff, and that the temperature has an influence on dogs performance. Results are discussed in the light of how cognitive abilities, motivation and odour perception influence each other.