Generalized rule application in bluestreak cleaner wrasse (<Emphasis Type="Italic">Labroides dimidiatus</Emphasis>): using predator species as social tools to reduce punishment

Generalized rule application promotes flexible behavior by allowing individuals to adjust quickly to environmental changes through generalization of previous learning. Here, we show that bluestreak ‘cleaner’ wrasse (Labroides dimidiatus) uses generalized rule application in their use of predators as social tools against punishing reef fish clients. Punishment occurs as cleaners do not only remove ectoparasites from clients, but prefer to feed on client mucus (constituting cheating). We tested for generalized rule application in a series of experiments, starting by training cleaners to approach one of two fish models in order to evade punishment (by chasing) from a ‘cheated’ client model. Cleaners learned this task only if the safe haven was a predator model. During consecutive exposure to pairs of novel species, including exotic models, cleaners demonstrated generalization of the ‘predators-are-safe-havens’ rule by rapidly satisfying learning criteria. However, cleaners were not able to generalize to a ‘one-of-two-stimuli-presents-a-safe-haven’ rule, as they failed to solve the task when confronted with either two harmless fish models or two predator models. Our results emphasize the importance of ecologically relevant experiments to uncover complex cognitive processes in non-human animals, like generalized rule learning in the context of social tool use in a fish.     

Seeing is believing: Utilization of subliminal symbols requires a visible relevant context

Sensory input that is not available for conscious report can still affect our behavior. Recent findings suggest that such subliminal information has the potency to influence behavior in a way that is dependent on the observer’s current intentions. Here, we investigate whether conscious observation of stimulus relevance provides an incentive for the utilization of nonconscious stimuli. We manipulated the predictive power of directional cues to selectively affect the incentive to utilize them for a subsequent target detection task. Central arrow cues rendered invisible by interocular suppression elicited a facilitatory cuing effect, but only when intermixed with visible arrow cues that were highly predictive with respect to (i.e., 80 % congruent with) the subsequent target location. When the visible cues were nonpredictive (50 % congruent), no subliminal cuing effect was found. An analysis of learning effects corroborates these findings; Cuing effects elicited by both visible and invisible cues increased over the course of the experiment, but only when intermixed visible cues were highly predictive. In a second experiment, we demonstrated that the intrinsic relevance of invisible cues (either 50 % or 100 % congruent) has no effect on the utilization of visible cues. We conclude that conscious perception is required to make statistical inferences about the relevance of symbolic cues. Once statistical information is extracted consciously, it affects subsequent nonconscious processing in a way that fits the current context. Accordingly, one of the possible functions of consciousness could be to extract general rules out of the conscious information, to provide guidelines for future behavior.     

Cleaner fish <Emphasis Type="Italic">Labroides dimidiatus</Emphasis> discriminate numbers but fail a mental number line test

Several species of primates, including humans, possess a spontaneous spatial mental arrangement (i.e. mental number line MNL) of increasing numbers or continuous quantities from left to right. This cognitive process has recently been documented in domestic chicken in a spatial–numerical task, opening the possibility that MNL is a cognitive capacity that has been conserved across vertebrate taxa. In this scenario, fish might possess the MNL as well. Here we investigated whether cleaner fish Labroides dimidiatus show evidence for MNL in two experiments. In Experiment I, we tested fish’s abilities in number discrimination, presenting simultaneously either small (2 vs 5) or large (5 vs 8) continuous quantities where one quantity was systematically rewarded. Experiment II used a protocol of an MNL task similar to the study on chickens. We trained cleaners with a target number (i.e. 5 elements), then we presented them with an identical pair of panels depicting either 2 elements or 8 elements, and we recorded their spontaneous choice for the left or right panel on each presentation. Cleaner fish showed high abilities in discriminating small and large numbers in Experiment I. Importantly, cleaners achieved this discrimination using numerical cues instead of non-numerical cues such as the cumulative surface area, density, and overall space. In contrast, cleaners did not allocate continuous quantities to space in Experiment II. Our findings suggest that cleaner fish possess numbering skills but they do not have an MNL. While similar studies on animals from various clades are needed to trace the evolution of MNL within vertebrates, our results suggest that this cognitive process might not be a capacity conserved across all vertebrate taxa.     

Learning to find the opponent: an ethological analysis of the behavior of paradise fish (Macropodus opercularis) in intra- and interspecific encounters.

In Experiment 1, 15 behavior patterns of male paradise fish (Macropodus opercularis; n = 72) toward a male conspecific, a male of another species, or no stimulus were recorded, both in home and novel situations. In Experiment 2, the same behaviors were recorded in a runway, and the same stimuli were used as reinforcers in the goal box (n = 18). A typical learning curve was seen when the subject found a male paradise fish in the goal box, learning was followed by apparent extinction when another species was found in the goal box, and few signs of learning were seen when the goal box was empty. Performance of the fish in both experiments can be accounted for by a strong aggressive motivation, a less strong but clear general curiosity, and habituation to the experimental procedure. In contrast to recent assertions in the literature, we conclude that aggressive behavior clearly can serve as a reinforcer in an instrumental learning situation.     

A single serotonergic modulatory cell can mediate reinforcement in the withdrawal network of the terrestrial snail

A cluster of 40 serotonergic cells in the rostral part of pedal ganglia of the terrestrial snail Helix lucorum was shown previously to participate in the modulation of withdrawal behavior and to be necessary during the acquisition of aversive withdrawal conditioning in intact snails. Local extracellular stimulation of the serotonergic cells paired with a test stimulus elicited a pairing-specific increase (the difference between paired and explicitly unpaired sessions was significant, p <.01) of synaptic responses to test stimulation in the premotor interneurons involved in withdrawal. This result suggested participation of serotonergic cells in mediating the reinforcement in the withdrawal network. Intracellular stimulation of only one identified Pd4 cell from the pedal group of serotonergic neurons paired with a test stimulus also significantly increased (the difference between paired and explicitly unpaired sessions was significant, p <.05) synaptic responses to paired nerve stimulation in same premotor interneurons involved in withdrawal. Morphological investigation of a cluster of pedal serotonergic neurons showed that only the Pd4 cell had branches in the parietal ganglia neuropile where the synapses of premotor withdrawal interneurons and of presynaptic neurons are located. The data suggest that a single serotonergic cell can mediate the reinforcement in the withdrawal network of the terrestrial snail. Patterns of responses of the Pd4 cells to tactile and chemical stimuli conform to the suggestion.     

Affect Dysregulation in Individuals With Borderline Personality Disorder: Persistence and Interpersonal Triggers

We hypothesized that affect dysregulation among individuals with borderline personality disorder (BPD) would involve greater persistence of negative affect between interpersonal events and heightened reactivity to stimuli indicating risk of rejection or disapproval, specifically perceptions of others’ communal (agreeable-quarrelsome) behaviors. A total of 38 participants with BPD and 31 controls collected information about affect and perceptions of the interaction partner's behavior during interpersonal events for a 20-day period. Negative and positive affect persisted more across interpersonal events for individuals with BPD than for controls. In addition, individuals with BPD reported a greater increase in negative affect when they perceived less communal behavior and a smaller increase in positive affect when they perceived more communal behavior in others. Findings indicate the importance of interpersonal perceptions in the affect dysregulation of individuals with BPD.     

Gustatory plasticity in C. elegans involves integration of negative cues and NaCl taste mediated by serotonin, dopamine, and glutamate

While na?ve Caenorhabditis elegans individuals are attracted to 0.1-200 mM NaCl, they become strongly repelled by these NaCl concentrations after prolonged exposure to 100 mM NaCl. We call this behavior gustatory plasticity. Here, we show that C. elegans displays avoidance of low NaCl concentrations only when pre-exposure to NaCl is combined with a negative stimulus, e.g., a repellent, or in the absence of food. By testing serotonin and/or dopamine signaling mutants and rescue by exogenously supplying these neurotransmitters, we found that serotonin and dopamine play a role during the plasticity response, while serotonin is also required during development. In addition, we also show that glutamate plays an important role in the response to NaCl, both in chemoattraction to NaCl and in gustatory plasticity. Thus, C. elegans can associate NaCl with negative stimuli using dopaminergic, serotonergic, and glutamatergic neurotransmission. Finally, we show that prolonged starvation enhances gustatory plasticity and can induce avoidance of NaCl in most gustatory plasticity mutants tested. Only mutation of the glutamate-gated Cl(-) channel gene avr-15 affected starvation-enhanced gustatory plasticity. These results suggest that starvation induces avoidance of NaCl largely independent of the normal gustatory plasticity mechanism.     

积极情绪对视觉注意的调节及其机制

在积极心理学思潮的推动下, 已有研究不但发现积极情绪扩展了空间和时间注意范围、增加了注意灵活性, 而且发现在积极情绪下个体对积极刺激表现出了注意偏向。对这些现象, 先前研究主要以积极情绪的扩展与建构理论、情绪信息等价说等理论来加以解释。但这些理论主要从宏观上强调情绪信息对注意加工的启动或积极情绪对注意资源分布的调节, 并不能清楚地揭示积极情绪对注意调节的内在机制。神经生化机制研究发现, 这些现象可能与多巴胺系统对注意控制能力的调节以及积极情绪对初级视觉皮层编码的调节有关。将来研究者可以基于不同的种类的注意选择和注意模型来进一步拓展积极情绪对注意调节的研究, 同时注重对其机制的探讨和理论的整合与创新。     

Improvements in hippocampal-dependent learning and decremental attention in 5-HT(3) receptor overexpressing mice

The 5-HT3 receptor for serotonin is expressed within limbic structures and is known to modulate neurotransmitter release, suggesting that this receptor may influence learning and memory. Perturbations in serotonergic neurotransmission lead to changes in the ability to attend, learn, and remember. To examine the role of 5-HT3 receptors in learning, memory, and attention, 5-HT3 receptor overexpressing (5-HT3-OE) transgenic mice and their wild-type littermates (WT) were tested in Pavlovian contextual and cued fear conditioning, fear extinction, and latent inhibition (LI) paradigms. Prepulse inhibition (PPI) was assessed to reveal changes in sensorimotor gating. Additionally, anxious behaviors, shock sensitivity, and reactions to novel stimuli were evaluated. 5-HT3-OE mice displayed enhanced contextual conditioning, whereas cued conditioning remained the same as that of WT mice. 5-HT3-OE mice did not differ from WT in extinction rates to either the context or cue. LI was enhanced for 5-HT3-OE mice compared to WT. PPI remained unchanged. No differences in sensitivity to footshock or startle were found. However, 5-HT3-OE mice demonstrated heightened exploratory behavior in response to novel environmental stimuli and decreased anxiety as measured in the elevated plus-maze. Results indicate that overexpression of the 5-HT3 receptor in mouse forebrain results in enhanced hippocampal-dependent learning and attention. Enhanced inspective behavior in response to novelty may contribute to the observed improvements in learning, memory, and attention due to 5-HT3 receptor overexpression.     

Intersensory redundancy accelerates preverbal numerical competence

Intersensory redundancy can facilitate animal and human behavior in areas as diverse as rhythm discrimination, signal detection, orienting responses, maternal call learning, and associative learning. In the realm of numerical development, infants show similar sensitivity to numerical differences in both the visual and auditory modalities. Using a habituation-dishabituation paradigm, we ask here, whether providing redundant, multisensory numerical information allows six-month-old infants to make more precise numerical discriminations. Results indicate that perceptually redundant information improved preverbal numerical precision to a level of discrimination previously thought attainable only after additional months of development. Multimodal stimuli may thus boost abstract cognitive abilities such as numerical competence.     

Emotional facial expressions affect visual rule learning in 7- to 8-month-old infants

Rule learning (RL) is an implicit learning mechanism that allows infants to detect and generalize rule-like repetition-based patterns (such as ABB and ABA) from a sequence of elements. Increasing evidence shows that RL operates both in the auditory and the visual domain and is modulated by the perceptual expertise with the to-be-learned stimuli. Yet, whether infants’ ability to detect a high-order rule from a sequence of stimuli is affected by affective information remains a largely unexplored issue. Using a visual habituation paradigm, we investigated whether the presence of emotional expressions with a positive and a negative value (i.e., happiness and anger) modulates 7- to 8-month-old infants’ ability to learn a rule-like pattern from a sequence of faces of different identities. Results demonstrate that emotional facial expressions (either positive and negative) modulate infants’ visual RL mechanism, even though positive and negative facial expressions affect infants’ RL in a different manner: while anger disrupts infants’ ability to learn the rule-like pattern from a face sequence, in the presence of a happy face infants show a familiarity preference, thus maintaining their learning ability. These findings show that emotional expressions exert an influence on infants’ RL abilities, contributing to the investigation on how emotion and cognition interact in face processing during infancy.     

The differential similarity of positive and negative information – an affect-induced processing outcome?

People judge positive information to be more alike than negative information. This good-bad asymmetry in similarity was argued to constitute a true property of the information ecology (Alves, H., Koch, A., & Unkelbach, C. (2017). Why good is more alike than bad: Processing implications. Trends in Cognitive Sciences, 21, 69–79). Alternatively, the asymmetry may constitute a processing outcome itself, namely an influence of phasic affect on information processing. Because no research has yet tested whether phasic affect influences perceived similarity among stimuli, we conducted 5 Experiments that also tested whether phasic affect can account for the higher judged similarity among positive compared to negative stimuli. In three experiments, we affectively charged pictures of different Pokemon by pairing them with monetary gains and losses (Exp. 1a, 1b) as well as positive and negative trait words (Exp. 2); yet, the evaluative charge did not differentially influence perceived similarity among the Pokemon. Experiment 3 replicated the basic similarity asymmetry among positive and negative words, and found that it was unaffected by externally induced phasic affect. Experiment 4 showed that phasic affect had no influence on perceived similarity of non-evaluative words either. We conclude that albeit a weak influence of phasic affect on perceived similarity of stimuli cannot be ruled out entirely, it can most likely not account for the typically medium to large sized asymmetry in similarity among positive and negative stimuli.     

物质成瘾及其戒除:基于反转学习的视角

物质成瘾与反转学习损伤密切相关,成瘾者往往不能灵活地适应变化的刺激—结果的联结,这可能进一步加剧成瘾者的物质使用。近年来研究发现,物质成瘾者的反转学习相关的腹外侧前额和背外侧前额等脑区激活异常,这些异常与成瘾者的冲动性和强迫性有关。此外,个体的反转学习能力对其成瘾行为具有一定预测性。今后应增加对不同类型物质成瘾者的反转学习脑机制及物质相关线索对成瘾者反转学习影响的研究,并且进一步探讨成瘾者的冲动性和强迫性对其反转学习的调节及个体反转学习能力对其成瘾行为的预测。     

Applying an exemplar model to an implicit rule-learning task: Implicit learning of semantic structure

Studies of implicit learning often examine peoples’ sensitivity to sequential structure. Computational accounts have evolved to reflect this bias. An experiment conducted by Neil and Higham [Neil, G. J., & Higham, P. A.(2012). Implicit learning of conjunctive rule sets: An alternative to artificial grammars. Consciousness and Cognition, 21, 1393–1400] points to limitations in the sequential approach. In the experiment, participants studied words selected according to a conjunctive rule. At test, participants discriminated rule-consistent from rule-violating words but could not verbalize the rule. Although the data elude explanation by sequential models, an exemplar model of implicit learning can explain them. To make the case, we simulate the full pattern of results by incorporating vector representations for the words used in the experiment, derived from the large-scale semantic space models LSA and BEAGLE, into an exemplar model of memory, MINERVA 2. We show that basic memory processes in a classic model of memory capture implicit learning of non-sequential rules, provided that stimuli are appropriately represented.     

Learning about non-predators and safe places: the forgotten elements of risk assessment

A fundamental prerequisite for prey to avoid being captured is the ability to distinguish dangerous stimuli such as predators and risky habitats from non-dangerous stimuli such as non-predators and safe locations. Most research to date has focused on mechanisms allowing prey to learn to recognize risky stimuli. The paradox of learned predator recognition is that its remarkable efficiency leaves room for potentially costly mistakes if prey inadvertently learn to recognize non-predatory species as dangerous. Here, we pre-exposed embryonic woodfrogs, Rana sylvatica, to the odour of a tiger salamander, Ambystoma tigrinum, without risk reinforcement, and later try to teach the tadpoles to recognize the salamander, a red-bellied newt Cynops pyrrhogaster—a closely related amphibian, or a goldfish, Carassius auratus, as a predator. Tadpoles were then tested for their responses to salamander, newt or fish odour. Pre-exposure to salamander did not affect the ability of tadpoles to learn to recognize goldfish as a predator. However, the embryonic pre-exposure to salamanders inhibited the subsequent learning of salamanders as a potential predator, through a mechanism known as latent inhibition. The embryonic pre-exposure also prevented the learned recognition of novel newts, indicating complete generalization of non-predator recognition. This pattern does not match that of generalization of predator recognition, whereby species learning to recognize a novel predator do respond, but not as strongly, to novel species closely related to the known predator. The current paper discusses the costs of making recognition mistakes within the context of generalization of predators and dangerous habitats versus generalization of non-predators and safe habitats and highlights the asymmetry in which amphibians incorporate information related to safe versus risky cues in their decision-making. Mechanisms such as latent inhibition allow a variety of prey species to collect information about non-threatening stimuli, as early as during their embryonic development, and to use this information later in life to infer the danger level associated with the stimuli.     

Exploring and Exploiting Uncertainty: Statistical Learning Ability Affects How We Learn to Process Language Along Multiple Dimensions of Experience

While the effects of pattern learning on language processing are well known, the way in which pattern learning shapes exploratory behavior has long gone unnoticed. We report on the way in which individual differences in statistical pattern learning affect performance in the domain of language along multiple dimensions. Analyzing data from healthy monolingual adults' performance on a serial reaction time task and a self-paced reading task, we show how individual differences in statistical pattern learning are reflected in readers' knowledge of linguistic co-occurrence patterns and in their exploration and exploitation of content-specific and task-general information. First, we investigated the extent to which an individual's pattern learning correlates with his or her sensitivity to systematic morphological and syntactic co-occurrences, as evidenced while reading authentic sentences. We found that the stream of morphological and syntactic information has a more pronounced effect on the reading speed of, as we will label them, content-sensitive learners in that the more probable the co-occurrence pattern, the faster their reading of that pattern will be. Next, we investigated how differences in pattern learning are reflected in the ways in which individuals approach the reading task itself and adapt to it. Casting this relation in terms of exploration/exploitation strategies, known from Reinforcement Learning, we conclude that content-sensitive learners are also more likely to initially probe (explore) a wider range of directly relevant patterns, which they can later use (exploit) to optimize their reading performance further. By affecting exploratory behavior, pattern learning influences the information that is gathered and becomes available for exploitation, thereby increasing the effect pattern learning has on language cognition.     

情绪词对新异刺激喜好度变化的调节机制

通过三个实验探讨了情绪词的情绪信息对新异刺激喜好度变化的调节机制。实验采用评价条件化(Evaluative Conditioning)范式, 将新异刺激(相当于条件刺激, CS)与情绪词(相当于无条件刺激, US)配对呈现, 最后测量被试对新异刺激的喜好程度。三个实验通过设置表面故事, 控制新异刺激与情绪词间的配对关系, 并改变任务的加工深度, 揭示了情绪词调节新异刺激喜好度变化的机制。研究结果表明, 情绪词对新异刺激喜好度的调节不依赖于对刺激间偶联关系的意识以及被试的任务状态, 是一种自下而上的自动化的联想学习过程。     

Complex learning and information processing by pigeons: a critical analysis

Three models of conditional discrimination learning by pigeons are described: stimulus configuration learning, the multiple-rule model, and concept learning. A review of the literature reveals that true concept learning is not characteristic of the behavior of pigeons in matching-to-sample, oddity-from-sample, or symbolic matching studies. Instead, pigeons learn a set of sample-specific S^D rules. Transfer of the discrimination to novel stimuli, at least along the hue dimension, is predicted by a “coding hypothesis”, which holds that pigeons make a unique, but usually unobserved response, R₁, to each sample, and that the comparison stimulus chosen depends on which R₁ was emitted in the presence of the sample. Convincing evidence is found that pigeons do code sample hues, but there is little evidence that allows one to infer that the “coding event” must have behavioral properties. Parameters of the conditional discrimination paradigm are identified, and it is shown that by appropriate parametric manipulation, a variety of analogous tasks may be generated for both human and animal subjects. The tasks make possible the comparative study of complex learning, attention, memory, and information processing, with the added advantage that behavior processes may be compared systematically across tasks.     

Cleaner fish Labroides dimidiatus recognise familiar clients

Individual recognition has been attributed a crucial role in the evolution of complex social systems such as helping behaviour and cooperation. A classical example for interspecific cooperation is the mutualism between the cleaner fish Labroides dimidiatus and its client reef fish species. For stable cooperation to evolve, it is generally assumed that partners interact repeatedly and remember each other's past behaviour. Repeated interactions may be achieved by site fidelity or individual recognition. However, as some cleaner fish have more than 2,300 interactions per day with various individuals per species and various species of clients, basic assumptions of cooperation theory might be violated in this mutualism. We tested the cleaner L. dimidiatus and its herbivorous client, the surgeon fish Ctenochaetus striatus, for their ability to distinguish between a familiar and an unfamiliar partner in a choice experiment. Under natural conditions, cleaners and clients have to build up their relationship, which is probably costly for both. We therefore predicted that both clients and cleaners should prefer the familiar partner in our choice experiment. We found that cleaners spent significantly more time near the familiar than the unfamiliar clients in the first 2 minutes of the experiment. This indicates the ability for individual recognition in cleaners. In contrast, the client C. striatus showed no significant preference. This could be due to a sampling artefact, possibly due to a lack of sufficient motivation. Alternatively, clients may not need to recognise their cleaners but instead remember the defined territories of L. dimidiatus to achieve repeated interactions with the same individual. Electronic Publication     

Feature modulation search: a novel memory search model that extends the perceptual interference effect to musical stimuli

Although most research in the perceptual interference literature has used visual stimuli, recent experiments have replicated this effect using musical stimuli. Two experiments investigated whether musical and visual demonstrations of the effect are produced by a common mechanism by examining whether the provision of incorrect cues would impair melodic object identification in the perceptual interference paradigm. Whereas incorrect cues typically do not affect visual object identification, they reduced melody identification both when the subjects generated the cues and when the experimenter provided them. A novel model (feature modulation search) is presented to account for perceptual interference in musical stimuli. The model has potential applications for the larger perceptual interference literature and for related phenomena in which target-related information impairs cognition.