Sex differences in aversive memory in rats: Possible role of extinction and reactive emotional factors

Studies usually show better spatial learning in males and stronger emotional memory in females. Spatial memory differences could relate to diverse strategies, while dissimilar stress reactions could cause emotional memory differences. We compared male and female rats in two emotional (classical emotional conditioning and aversive discrimination memory) and two emotionally “neutral” tasks: (1) plus-maze discriminative avoidance, containing two open and two enclosed arms, one of which presenting aversive stimuli (light/noise). No differences were found in learning, retrieving, or basal emotional levels, while only male rats presented extinction of the task; (2) contextual fear conditioning – a cage was paired to mild foot shocks. Upon reexposure, freezing behavior was decreased in females; (3) spontaneous alternation – the animals were expected to alternate among the arms of a four-arm maze. No differences between genders were found and (4) open-field habituation was addressed in an arena which the rats were allowed to explore for 10 min. Habituation was similar between genders. Differences were found only in tasks with strong emotional contexts, where different fear responses and stress effects could be determinant. The lack of extinction of discriminative avoidance by females points out to stronger consolidation and/or impaired extinction of aversive memories.     

The dark side of cognitive illusions: When an illusory belief interferes with the acquisition of evidence‐based knowledge

Cognitive illusions are often associated with mental health and well‐being. However, they are not without risk. This research shows they can interfere with the acquisition of evidence‐based knowledge. During the first phase of the experiment, one group of participants was induced to develop a strong illusion that a placebo medicine was effective to treat a fictitious disease, whereas another group was induced to develop a weak illusion. Then, in Phase 2, both groups observed fictitious patients who always took the bogus treatment simultaneously with a second treatment which was effective. Our results showed that the group who developed the strong illusion about the effectiveness of the bogus treatment during Phase 1 had more difficulties in learning during Phase 2 that the added treatment was effective.     

High working memory load leads to more Ebbinghaus illusion

The evidence that distractor processing increases with greater load on working memory has come mainly from Stroop-type interference tasks, making it difficult to establish whether cognitive load affects distractor processing at the perceptual level or during response selection. We measured the Ebbinghaus illusion under varying levels of working memory load to test whether cognitive control is also relevant for preventing processing of distractors that do not produce any response conflict, and instead affect target processing at the perceptual level. The Ebbinghaus illusion was greater under high working memory load, suggesting that availability of cognitive control functions is critical to reduce distractor processing even for distractors that are not associated with a response. We conclude that the effect of loading working memory during selective attention leads to greater distractor perception.     

Dissociating electrophysiological correlates of subjective,objective, and correct memory in investigating the emotion-induced recognition bias

Performance on tasks requiring discrimination of at least two stimuli can be viewed either from an objective perspective (referring to actual stimulus differences), or from a subjective perspective (corresponding to participant’s responses). Using event-related potentials recorded during an old/new recognition memory test involving emotionally laden and neutral words studied either blockwise or randomly intermixed, we show here how the objective perspective (old versus new items) yields late effects of blockwise emotional item presentation at parietal sites that the subjective perspective fails to find, whereas the subjective perspective (“old” versus “new” responses) is more sensitive to early effects of emotion at anterior sites than the objective perspective. Our results demonstrate the potential advantage of dissociating the subjective and the objective perspective onto task performance (in addition to analyzing trials with correct responses), especially for investigations of illusions and information processing biases, in behavioral and cognitive neuroscience studies.     

Visual enhancement of touch and the bodily self

We experience our own body through both touch and vision. We further see that others’ bodies are similar to our own body, but we have no direct experience of touch on others’ bodies. Therefore, relations between vision and touch are important for the sense of self and for mental representation of one’s own body. For example, seeing the hand improves tactile acuity on the hand, compared to seeing a non-hand object. While several studies have demonstrated this visual enhancement of touch (VET) effect, its relation to the ‘bodily self’, or mental representation of one’s own body remains unclear. We examined whether VET is an effect of seeing a hand, or of seeing my hand, using the rubber hand illusion. In this illusion, a prosthetic hand which is brushed synchronously—but not asynchronously—with one’s own hand is felt to actually be one’s hand. Thus, we manipulated whether or not participants felt like they were looking directly at their hand, while holding the actual stimulus they viewed constant. Tactile acuity was measured by having participants judge the orientation of square-wave gratings. Two characteristic effects of VET were observed: (1) cross-modal enhancement from seeing the hand was inversely related to overall tactile acuity, and (2) participants near sensory threshold showed significant improvement following synchronous stroking, compared to asynchronous stroking or no stroking at all. These results demonstrate a clear functional relation between the bodily self and basic tactile perception.     

Deficits in acquisition and extinction of conditioned responses in mGluR7 knockout mice

Metabotropic glutamate receptor 7 (mGluR7) is expressed in brain regions implicated in emotional learning and working memory, and previous behavioral experiments indicated contributions of mGluR7 to various complex behaviors. In the present study, we investigated the specific effects of mGluR7 deletion on a variety of conditioning paradigms that model crucial neurocognitive and psychopathological behavioral phenomena. Null-mutant mGluR7^−/− mice displayed defects during scheduled appetitive conditioning, acquisition and extinction of appetitive odor conditioning, extinction of response suppression-based conditioned emotional responding (CER), acquisition of discriminative CER, and contextual fear conditioning. mGluR7^−/− animals were slower to acquire the association between a conditioned stimulus and a positive or negative reinforcer, but eventually reached similar performance levels to their wildtype littermates. Notably, extinction learning of conditioned responses was slower in mGluR7^−/− compared to wildtype animals. The observed delays in the acquisition of complicated stimulus associations across conditioning procedures may suggest a critical role for mGluR7 in neurocognitive functions and psychopathology.     

Reversed PREE under multiple schedules: Exploration of a modulation hypothesis

When reinforcer rates are manipulated in within-subjects designs, persistence in subsequent extinction trials is sometimes greater to the response alternative associated with the higher reinforcer rate (“reversed” partial reinforcement extinction effect, RPREE). The RPREE is often held to be a contradiction to the conventional PREE. To explore the interaction between these effects, student subjects were exposed to a multiple high-density and low-density reinforcement schedule, then to extinction conditions. Subjects in two control conditions received the high- and low-density schedules only. For all groups, general extinction persistence was elevated, and a within-subjects RPREE occurred under the multiple schedule. The RPREE was caused by the low-density component increasing persistence to the high-density component; the high-density component did not decrease persistence to the low-density component. These results support the view that the RPREE may be a within-subjects effect of the conventional PREE.     

双加工发展理论新探——兼及中国一古老推理错觉的跨年级特征

为了检验双加工发展理论及了解中国一古老推理错觉问题的发展特征,从小学五年级至大学二年级各个阶段选取被试385名,对该古老推理错觉及其改良版问题的发展特征进行了调查。结果发现：（1）该古老推理错觉问题及其改良版问题的趋势对比有力的支持了双加工发展理论; （2）从小学五年级始,财会关系推理错觉即存在,表现出跨年级的发展特征。     

十文钱问题再探

本研究设计了三个实验,探讨了被试在经典的十文钱问题以及与其异质同构的组团旅游问题中的推理情况。实验1通过调查法发现,被试在十文钱异质同构问题中表现出了与十文钱问题同样高的错误率,属于推理错觉问题。在此基础上,实验二、三就其推理错误的可能原因进行了实证探究,结果发现：（1）题目表面特征的弱化能显著提高被试的推理成绩。（2）批判性思维意识与批判性思维技巧的线索提示能显著提高被试的推理成绩。