Leopard frog priorities in choosing between prey at different locations

Frogs are able to respond to a prey stimulus throughout their 360° ground-level visual field as well as in the superior visual field. We compared the likelihood of frogs choosing between a more nasally located, ground-level prey versus a more temporally located ground-level prey, when the prey at the nasal location is further away from the frog. Two crickets were presented simultaneously at 9 pairs of angles that included both crickets in the binocular visual field, both crickets in the monocular visual field, or one cricket in the binocular field and one in the monocular field. Frogs chose the more nasally located prey at least 71% of the time when the more temporal prey was in the monocular field; and 64% of the time when both prey were in the binocular field. Frogs tended to choose the more nasally located prey, even though it takes the frog longer to reach the prey. In addition, when given a choice between a prey located at ground level versus a prey located in the superior field, frogs tend to choose the prey at ground-level. These results suggest that there is a neural mechanism that biases frogs’ responses to prey stimuli.     

The forest or the trees: preference for global over local image processing is reversed by prior experience in honeybees

Traditional models of insect vision have assumed that insects are only capable of low-level analysis of local cues and are incapable of global, holistic perception. However, recent studies on honeybee (Apis mellifera) vision have refuted this view by showing that this insect also processes complex visual information by using spatial configurations or relational rules. In the light of these findings, we asked whether bees prioritize global configurations or local cues by setting these two levels of image analysis in competition. We trained individual free-flying honeybees to discriminate hierarchical visual stimuli within a Y-maze and tested bees with novel stimuli in which local and/or global cues were manipulated. We demonstrate that even when local information is accessible, bees prefer global information, thus relying mainly on the object''s spatial configuration rather than on elemental, local information. This preference can be reversed if bees are pre-trained to discriminate isolated local cues. In this case, bees prefer the hierarchical stimuli with the local elements previously primed even if they build an incorrect global configuration. Pre-training with local cues induces a generic attentional bias towards any local elements as local information is prioritized in the test, even if the local cues used in the test are different from the pre-trained ones. Our results thus underline the plasticity of visual processing in insects and provide new insights for the comparative analysis of visual recognition in humans and animals.     

European starlings recognize the location of robotic conspecific attention

Looking where others are allocating attention can facilitate social interactions by providing information about objects or locations of interest. We asked whether European starlings follow the orientation behaviour of conspecifics owing to their highly gregarious behaviour. Starlings reoriented their attention to follow that of a robot around a barrier more often than when the robot''s attention was directed elsewhere. This is the first empirical evidence of reorienting in response to conspecific attention in a songbird. Starlings may use this behaviour to obtain fine-tuned spatial information from conspecifics (e.g. direction of predator approach, spatial location of food patches), enhancing group cohesion.     

Attention control in the primate brain

Attention is fundamental to all cognition. In the primate brain, it is implemented by a large-scale network that consists of areas spanning across all major lobes, also including subcortical regions. Classical attention accounts assume that control over the selection process in this network is exerted by ‘top-down’ mechanisms in the fronto-parietal cortex that influence sensory representations via feedback signals. More recent studies have expanded this view of attentional control. In this review, we will start from a traditional top-down account of attention control, and then discuss more recent findings on feature-based attention, thalamic influences, temporal network dynamics, and behavioral dynamics that collectively lead to substantial modifications. We outline how the different emerging accounts can be reconciled and integrated into a unified theory.     

不同注意任务类型及难度对猕猴微眼动的影响

微眼动是视觉注视过程中幅度最大、速度最快的眼动,可以消除由于神经系统适应性而产生的视觉衰退现象,在视觉信息处理过程中发挥着重要作用.基于微眼动与视觉感知功能的相关性,设计实验研究猕猴完成显性、隐性注意任务以及不同难度显性注意任务时,视觉注视情况下微眼动的差异.通过对不同难度显性注意任务下微眼动的参数进行比较,发现随着任务难度的增加,微眼动的幅度、速率和频率都被抑制.另一方面,对比不同类型的视觉感知任务(显性注意和隐性注意),发现在相似的实验范式下,隐性注意对微眼动的频率有明显的抑制作用,但幅度和频率没有得到一致的结果,这表明视觉注意任务类型的不同或将导致猕猴完成任务的策略不同.这些工作将为今后进一步研究微眼动产生的神经机制以及视觉注意过程中眼动的作用机制奠定良好的基础.     

Feature-based attention: it is all bottom-up priming

Feature-based attention (FBA) enhances the representation of image characteristics throughout the visual field, a mechanism that is particularly useful when searching for a specific stimulus feature. Even though most theories of visual search implicitly or explicitly assume that FBA is under top-down control, we argue that the role of top-down processing in FBA may be limited. Our review of the literature indicates that all behavioural and neuro-imaging studies investigating FBA suffer from the shortcoming that they cannot rule out an effect of priming. The mere attending to a feature enhances the mandatory processing of that feature across the visual field, an effect that is likely to occur in an automatic, bottom-up way. Studies that have investigated the feasibility of FBA by means of cueing paradigms suggest that the role of top-down processing in FBA is limited (e.g. prepare for red). Instead, the actual processing of the stimulus is needed to cause the mandatory tuning of responses throughout the visual field. We conclude that it is likely that all FBA effects reported previously are the result of bottom-up priming.     

Intergroup threat gates social attention in humans

Humans shift their attention to follow another person''s gaze direction, a phenomenon called gaze cueing. This study examined whether a particular social factor, intergroup threat, modulates gaze cueing. As expected, stronger responses of a particular in-group to a threatening out-group were observed when the in-group, conditioned to perceive threat from one of two out-groups, was presented with facial stimuli from the threatening and non-threatening out-groups. These results suggest that intergroup threat plays an important role in shaping social attention. Furthermore, larger gaze-cueing effects were found for threatening out-group faces than for in-group faces only at the 200 ms but not the 800 ms stimulus onset asynchrony (SOA); the specificity of the gaze-cueing effects at the short SOA suggests that threat cues modulate the involuntary component of gaze cueing.     

A Feedback Model of Attention and Context Dependence in Visual Cortical Networks

We have modeled biologically realistic neural networks that may be involved in contextual modulation of stimulus responses, as reported in the neurophysiological experiments of Motter (1994a, 1994b) (Journal of Neuroscience, 14:2179–2189 and 2190–2199). The networks of our model are structured hierarchically with feedforward, feedback, and lateral connections, totaling several thousand cells and about 300,000 synapses. The contextual modulation, arising from attention cues, is explicitly modeled as a feedback signal coming from the highest-order cortical network. The feedback signal arises from mutually inhibitory neurons with different stimulus preferences. Although our model is probably the simplest one consistent with available anatomical and physiological evidence and ignores the complexities that may exist in high-level cortical networks such as the prefrontal cortex, it reproduces the experimental results quite well and offers some guidance for future experiments. We also report the unexpected observation of 40 Hz oscillations in the model.     

Attention driven phantom vision: measuring the sensory strength of attentional templates and their relation to visual mental imagery and aphantasia

When we search for an object in an array or anticipate attending to a future object, we create an ‘attentional template'' of the object. The definitions of attentional templates and visual imagery share many similarities as well as many of the same neural characteristics. However, the phenomenology of these attentional templates and their neural similarities to visual imagery and perception are rarely, if ever discussed. Here, we investigate the relationship between these two forms of non-retinal phantom vision through the use of the binocular rivalry technique, which allows us to measure the sensory strength of attentional templates in the absence of concurrent perceptual stimuli. We find that attentional templates correlate with both feature-based attention and visual imagery. Attentional templates, like imagery, were significantly disrupted by the presence of irrelevant visual stimuli, while feature-based attention was not. We also found that a special population who lack the ability to visualize (aphantasia), showed evidence of feature-based attention when measured using the binocular rivalry paradigm, but not attentional templates. Taken together, these data suggest functional similarities between attentional templates and visual imagery, advancing the theory of visual imagery as a general simulation tool used across cognition.This article is part of the theme issue ‘Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation’.     

Social orienting in gaze leading: a mechanism for shared attention

Here, we report a novel social orienting response that occurs after viewing averted gaze. We show, in three experiments, that when a person looks from one location to an object, attention then shifts towards the face of an individual who has subsequently followed the person''s gaze to that same object. That is, contrary to ‘gaze following’, attention instead orients in the opposite direction to observed gaze and towards the gazing face. The magnitude of attentional orienting towards a face that ‘follows’ the participant''s gaze is also associated with self-reported autism-like traits. We propose that this gaze leading phenomenon implies the existence of a mechanism in the human social cognitive system for detecting when one''s gaze has been followed, in order to establish ‘shared attention’ and maintain the ongoing interaction.     

线索有效性对社会性注意和外源性注意的影响

目的 眼睛注视、头朝向和生物运动方向等社会性线索,对人类的生存和社会交互极为重要.由于社会性线索和外周线索都具有反射性注意定向这一特点,社会性注意往往也被认为属于外源性注意.但是,外源性注意并不能完全解释所有的社会性注意现象.因此,两者是否具有相同的加工机制,尚存在争论.方法 本研究使用空间线索范式,系统考察了线索有效...     

Grapheme-colour synaesthesia improves detection of embedded shapes,but without pre-attentive ‘pop-out’ of synaesthetic colour

For people with synaesthesia letters and numbers may evoke experiences of colour. It has been previously demonstrated that these synaesthetes may be better at detecting a triangle made of 2s among a background of 5s if they perceive 5 and 2 as having different synaesthetic colours. However, other studies using this task (or tasks based on the same principle) have failed to replicate the effect or have suggested alternative explanations of the effect. In this study, we repeat the original study on a larger group of synaesthetes (n = 36) and include, for the first time, an assessment of their self-reported colour experiences. We show that synaesthetes do have a general advantage over controls on this task. However, many synaesthetes report no colour experiences at all during the task. Synaesthetes who do report colour typically experience around one third of the graphemes in the display as coloured. This is more consistent with theories of synaesthesia in which spatial attention needs to be deployed to graphemes for conscious colour experiences to emerge than the interpretation based on ‘pop-out’.     

选择性注意的统一模型

根据ＰＥＴ、ＥＲＰ和心理学实验的事实,提出选择性注意的统一模型。在统一模型,把探照灯模型和偏置竞争模型和特点结合起来,既包括竞争机制,又包括增强机制。