Computational Versus Associative Models of Simple Conditioning

In associative models of simple conditioning, conductive connections (associations, Hebbian synapses) are strengthened by the repetitive temporal pairing of stimuli. The associations cause the animal to behave more adaptively, but they do not encode information about objectively specifiable properties of the conditioning experience. In information processing (computational) models, the temporal intervals in that experience are timed and the results recorded in memory for later use in computations that determine the decisions whether and when to respond to the conditioned stimulus. The predictions of these latter models depend on the ratios of remembered and currently experienced temporal intervals; hence, they are time-scale invariant. Two examples of empirical time-scale invariance are described: Neither the delay of reinforcement nor the ratio of reinforced to unreinforced presentations of the conditioned stimulus affects rates of acquisition and extinction. Time-scale invariance has far-reaching implications for models of the processes that underlie conditioning, for example, models of Hebbian synapses.     

Mentoring: Some ethical considerations

To counter confusion about the term ‘mentor’, and address concerns about the scarcity of mentoring, I argue for an “honorific” definition, according to which a mentor is virtuous like a saint or hero. Given the unbounded commitment of mentors, mentoring relationships must be voluntary. In contrast, the role of advisor can be specified, mandated, and monitored. I argue that departments and research groups have a moral responsibility to devise a system of roles and structures to meet graduate students’ and postdoctoral fellows’ needs for information and advice. An earlier version of this paper was presented at a conference sponsored by the National Science Foundation on Mentoring and Research Values: Students as Vital Human Resources, Chicago, March 1995.     

The importance of impaired physical health and age in normal cognitive aging

The objective of this study was to investigate the importance of impaired physical health and age in normal cognitive aging. In our cross-sectional, clinical and explorative study, medical and neuropsychological data from 118 voluntary healthy controls aged 26-91 years were collected from five recruitment occasions. Health was assessed according to a criterion reflecting clinical and subclinical severity. The examinations included a clinical investigation, brain neuroimaging, and a comprehensive neuropsychological assessment. Regression analyses showed a significant incidence of clinical and subclinical medical disorders that explained 10.8% of the variation in cognitive performance, while age-related impairment explained 5.6%. Findings of the central nervous system were important but various other medical findings explained about half of the health-related variation. Cognitively demanding tasks were more susceptible to impaired physical health while tasks comprising salient motor- and visual spatial elements were more prone to be impaired by age. Our findings suggest (1) that impaired physical health is more important than chronological age in accounting for cognitive impairment across the adult lifespan, (2) that age and health dissociate with regard to cognitive functions affected, and (3) that selection for so-called "super healthy" elderly people might be justified in cognitive research. Because the prevalent diseases in normal aging are potentially preventable, the present findings promise good prospect for prevention of future cognitive disability among elderly people.     

运动、语言和学习：小脑的功能磁共振成像研究

对小脑功能的认识在过去的100年里经历了缓慢而稳定的发展。在最近20年,随着活体神经影像技术尤其是功能磁共振成像（fMRI）的出现,这一领域取得了更加显著的进展。文章简要总结了我们最近关于小脑的fMRI研究,考察了该结构在运动、语言和学习任务中的作用;并通过回顾相关文献,讨论了这些研究的理论意义。小脑的功能本质似乎是一般性的而非通道特异的,动态的而非静态的,联系的而非孤立的。作者提出,研究小脑与大脑之间的相互作用和合作机制将是小脑研究领域的新的生长点     

Incongruent object/context relationships in visual scenes: Where are they processed in the brain?

Rapid object visual categorization in briefly flashed natural scenes is influenced by the surrounding context. The neural correlates underlying reduced categorization performance in response to incongruent object/context associations remain unclear and were investigated in the present study using fMRI. Participants were instructed to categorize objects in briefly presented scenes (exposure duration = 100 ms). Half of the scenes consisted of objects pasted in an expected (congruent) context, whereas for the other half, objects were embedded in incongruent contexts. Object categorization was more accurate and faster in congruent relative to incongruent scenes. Moreover, we found that the two types of scenes elicited different patterns of cerebral activation. In particular, the processing of incongruent scenes induced increased activations in the parahippocampal cortex, as well as in the right frontal cortex. This higher activity may indicate additional neural processing of the novel (non experienced) contextual associations that were inherent to the incongruent scenes. Moreover, our results suggest that the locus of object categorization impairment due to contextual incongruence is in the right anterior parahippocampal cortex. Indeed in this region activity was correlated with the reaction time increase observed with incongruent scenes. Representations for associations between objects and their usual context of appearance might be encoded in the right anterior parahippocampal cortex.     

Blue or red? The effects of colour on the emotions of Chinese people

Two experiments were performed to examine the effects of red and blue on the emotional pleasure of Chinese people. Experiment 1 explored the effects of the ‘physical’ colours red and blue on emotion, and the results showed that red induced positive and negative emotion, while blue only induced positive emotion. Experiment 2 further explored the effects of the ‘verbal’ colours red and blue on emotion, and the results showed that red induced only positive emotion, while blue induced neither positive nor negative emotion. The findings indicate that the influence of colour on emotion is rooted in both natural and social associations. For Chinese, the associations between blue and positive emotion, and red and negative emotion, were natural associations; however, the associations between red and positive emotion were social associations. Moreover, physical colour and verbal colour stimuli induced emotions by activating different mechanisms: physical colour induced emotions via both natural and social associations, whereas verbal colour induced emotions via social associations.     

When implicit fails: Explicit but not implicit attitudes predict choices of decided and undecided voters

IntroductionA recent study (Friese et al., 2012) involving two major political elections in the US and Germany reported that voting behavior was better predicted by explicit than implicit attitudes for both decided and undecided voters and that when voting behavior was predicted by implicit attitudes, the prediction was better for decided than undecided voters.ObjectiveWe conducted a comparable study for the 2012 French presidential election using voter volatility as a measure of voter decidedness, in order to test the generalizability of the findings of Friese et al. (2012).MethodParticipants’ voting intention, explicit and implicit attitudes towards the candidates Sarkozy and Hollande were collected during the 2 weeks separating the two rounds of the election.ResultsOur findings confirm that explicit attitudes outperform implicit attitudes when predicting voting choice, but not that the relationship between implicit attitudes and voting intention is moderated by voter decidedness.ConclusionFurther research is needed in order to test whether the moderation of implicit attitudes by voter decidedness is a robust finding or not.     

Larger,smaller, odd or even? Task-specific effects of optokinetic stimulation on the mental number space

Previous studies have shown that number processing can induce spatial biases in perception and action and can trigger the orienting of visuospatial attention. Few studies, however, have investigated how spatial processing and visuospatial attention influences number processing. In the present study, we used the optokinetic stimulation (OKS) technique to trigger eye movements and thus overt orienting of visuospatial attention. Participants were asked to stare at OKS, while performing parity judgements (Experiment 1) or number comparison (Experiment 2), two numerical tasks that differ in terms of demands on magnitude processing. Numerical stimuli were acoustically presented, and participants responded orally. We examined the effects of OKS direction (leftward or rightward) on number processing. The results showed that rightward OKS abolished the classic number size effect (i.e., faster reaction times for small than large numbers) in the comparison task, whereas the parity task was unaffected by OKS direction. The effect of OKS highlights a link between visuospatial orienting and processing of number magnitude that is complementary to the more established link between numerical and visuospatial processing. We suggest that the bidirectional link between numbers and space is embodied in the mechanisms subserving sensorimotor transformations for the control of eye movements and spatial attention.     

Mechanisms for the object-based negative compatibility effect: voluntary versus involuntary inhibition

This study investigates whether the object-based negative compatibility effect (NCE) originates from involuntary or voluntary inhibition. We hypothesised that both supraliminally presented primes (the prime is a mug with its handle pointing either left or right) and experimental instructions (i.e., ignoring the prime) in previous studies might induce participants to develop a voluntarily inhibitory strategy that is responsible for the object-based NCE. To test this hypothesis, we conducted 3 experiments. Experiment 1 confirmed a suitable paradigm. Experiment 2 altered participants’ strategies by varying the frequency of compatible trials across blocks. The results revealed a significant NCE for the low-frequency condition, which suggested that voluntary strategy might be primarily responsible for the object-based NCE. Experiment 3 combined a free-choice target with an object-based NCE paradigm. The results showed equivalent frequencies and mean response times between the free-choice responses that corresponded to or were opposite from the orientations of the mug handle. Combined with the results of response time quartiles, which revealed NCEs in fast responses (Q1–Q3) but no compatibility effect in slow (Q4) responses, we concluded that the object-based NCE might be primarily based on voluntary inhibition. Moreover, this inhibition might take effect earlier than that of the arrow-based NCE.