Visual dominance in olfactory memory

The object of the present study was to verify the emergence of a 'visual dominance' effect in memory tests involving different sensory modes (sight and smell), brought about the preattentive mechanisms which select the visual sensory mode regardless of the recall task.     

Dynamic visual capture: apparent auditory motion induced by a moving visual target

Apparent motion of a sound source can be induced by a moving visual target. The direction of the perceived motion of the sound source is the same as that of the visual target, but the subjective velocity of the sound source is 25-50% of that of the visual target measured under the same conditions. Eye tracking of the light target tends to enhance the apparent motion of the sound, but is not a prerequisite for its occurrence. The findings are discussed in connection with the 'visual capture' or 'ventriloquism' effect.     

The visual light field

Human observers are sensitive to the '(physical) light field' in the sense that they have expectations of how a given object would appear if it were introduced in the scene in front of them at some arbitrary location. Thus the 'visual light field' is defined even in the 'empty space' between objects. In that sense the light field is akin to visual space considered as a 'container'. The visual light field at any given point can be measured in psychophysical experiments through the introduction of a suitable 'gauge object' at that position and letting the observer adjust the appearance of that gauge object (eg through suitable computer rendering) so as to produce a 'visual fit' into the scene. The parameters of the rendering will then be considered as the measurement result. We introduced white spheres as gauge objects at various locations in stereoscopically presented photographic scenes. We measured the direction ('direction of the light'), diffuseness ('quality of the light' as used by photographers and interior decorators), and intensity of the light field. We used three very different scenes, with very different physical light fields. The images were geometrically and photometrically calibrated, so we were in a position to correlate the observations with the physical 'ground truth'. We report that human observers are quite sensitive to various parameters of the physical light field and generally arrive at close to veridical settings, although a number of comparatively minor systematic deviations from veridicality can be noted. We conclude that the visual light field is an entity whose existence is at least as well defined as that of visual space, despite the fact that the visual light field hardly appears as prominently in vision science as it does in the visual arts.     

Situating vision in the world

Recently, there has been a great deal of interest in what has been called 'situated cognition', which has included claims that certain forms of representation are inadequate for modeling active organisms or agents such as humans and robots. In this article, I suggest that a weakness in classical theories of visual representation is the way in which representations connect with the real world, which may account for many of the concerns expressed by the situated cognition community. Specifically, I claim that what current theories lack is any provision for a certain form of direct, preconceptual connection between objects in the visual world (visual objects or proto-objects) and their representations in the visual system. This type of connection is akin to what philosophers and semanticists have referred to as an 'indexical' or 'demonstrative' reference and what some cognitive scientists have referred to as 'deictic pointers'. I explain why such a mechanism is needed and suggest that many workers have, in fact, been studying precisely this under the term 'visual index'. The visual index hypothesis is illustrated with the results of some relevant experiments, including multiple object tracking, visual routines and subset-selected visual searches. Indexing theory provides a synthesis that has profound implications for explaining a wide range of psychophysical findings, certain results in infant cognitive development and also some ancient problems in the philosophy of mind.     

The earliest electrophysiological correlate of visual awareness?

To examine the neural correlates and timing of human visual awareness, we recorded event-related potentials (ERPs) in two experiments while the observers were detecting a grey dot that was presented near subjective threshold. ERPs were averaged for conscious detections of the stimulus (hits) and nondetections (misses) separately. Our results revealed that hits, as compared to misses, showed a negativity around 180-350 ms at occipital and posterior temporal sites. It was followed by a positive wave after 400-500 ms, peaking at parietal sites. These correlates were not affected by a manipulation of attention. The early negativity, called 'visual awareness negativity' (VAN), may be a general, primary electrophysiological correlate of visual awareness. The present data show that it can be observed in response to appearance of a stimulus in visual awareness and that it generalizes across different manipulations of stimulus visibility.     

Search of jumping items: visual marking and discrete motion

Watson and Humphreys (1997 Psychological Review 104 90-122) showed that when searching for a target, observers can ignore a previewed set of distractors (other items), effectively decreasing the number of relevant items in a difficult search display and thus speeding performance ('visual marking'). Other researchers have more recently investigated visual marking for continuously moving items, finding that shared features, and preserved inter-item spatial relationships, are helpful. Here, we tested whether visual marking occurs for a set of initial items that moves in one discrete jump (preserving shared features and inter-item spatial relationships). Marking did not occur in these displays, and we interpret this result in the context of previous research on visual marking.     

Facilitating ambulation and activity in persons with profound multiple disabilities through a visual orientation system

A visual orientation system was employed to help two adults with profound multiple disabilities ambulate to programmed activity destinations and carry out familiar activities. The system consisted of a portable control device and light sources. The person participating in experiment 1 was to operate the control device for activating the programmed destinations (and turning on light sources showing the way to them). The person participating in experiment 2 did not need to operate the control device; this activated each programmed destination automatically. A new destination was activated after a preset time had elapsed from the person reaching the previous destination. Results indicated that both persons used the visual orientation system successfully and thus could reach the destinations and carry out activities on their own. General implications of the findings are discussed. © 1998 John Wiley & Sons, Ltd.     

The contribution of colour to three-dimensional ambiguities in paintings and drawings.

This paper is about kinds of visual ambiguity that concern the author as a painter. Some effects of incompatible depth cues on the experience of looking at paintings and drawings are discussed. Particular attention is given to the role of colour as a depth cue. It is suggested that areas of identical pigmentation on different parts of a picture surface tend to be interpreted as being on the same plane. Where this interpretation is incompatible with other depth cues 'visual tension' results, the degree of tension being dependent on the relative strength of the cues involved. This hypothesis is illustrated and elaborated with the help of a number of line drawings.     

The aesthetic appeal of auditory-visual synaesthetic perceptions in people without synaesthesia

The term 'visual music' refers to works of art in which both hearing and vision are directly or indirectly stimulated. Our ability to create, perceive, and appreciate visual music is hypothesised to rely on the same multisensory processes that support auditory visual (AV) integration in other contexts. Whilst these mechanisms have been extensively studied, there has been little research on how these processes affect aesthetic judgments (of liking or preference). Studies of synaesthesia in which sound evokes vision and studies of cross-modal biases in non-synaesthetes have revealed non-arbitrary mappings between visual and auditory properties (eg high-pitch sounds being smaller and brighter). In three experiments, we presented members of the general population with animated AV clips derived from synaesthetic experiences and contrasted them with a number of control conditions. The control conditions consisted of the same clips rotated or with the colour changed, random AV pairings, or animated clips generated by non-synaesthetes. Synaesthetic AV animations were generally preferred over the control conditions. The results suggest that non-arbitrary AV mappings, present in the experiences of synaesthetes, can be readily appreciated by others and may underpin our tendency to engage with certain forms of art.     

Visual rays are parallel

We show that human observers using monocular viewing treat the pencil of 'visual rays' that diverges from the vantage point as experientally parallel. This oddity becomes very noticeable in the case of wide-angle presentations, where the angle subtended by a pair of visual rays may be as large as the angular size of the display. In our presentations such angles subtended over 100 deg. There are various ways to demonstrate the effect; in this study we measure the attitudes of pictorial objects that appear to be situated in mutually parallel attitudes in pictorial space. Our finding is that such objects appear parallel if they are similarly oriented with respect to the local visual rays. This leads to 'errors' in the judgment of mutual orientations of up to 100 deg. Although this appears to be the first quantitative study of the effect, we trace it to qualitative reports by Helmholtz (late 19th century) and Kepler (early 17th century) as well as speculation by early authors (AD 500). The effect has apparently been noticed by visual artists from the late middle ages to the present day.     

The influence of surface and edge-based visual similarity on object recognition

The role of 'visual similarity' has been emphasised in object recognition and in particular, for category-specific agnosias. [Laws and Gale, 2002] recently described a measure of pixel-level visual overlap for line drawings (Euclidean Overlap: EO[line]) that distinguished living and nonliving things and predicted normal naming errors and latencies ( [Laws et al., 2002]). Nevertheless, it is important to extend such analyses to stimuli other than line drawings. We therefore developed the same measure for greyscale versions of the same stimuli (EO[grey]), i.e., that contain shading and texture information. EO[grey], however, failed to differentiate living from nonliving things and failed to correlate with naming latencies to the greyscale images. By contrast, EO[line] did correlate with the naming latencies. This suggests that similarity of edge information is more influential than similarity of surface characteristics for naming and for categorically separating living and nonliving things (be they line drawings or greyscale images).     

The neural basis of the right visual field advantage in reading: an MEG analysis using virtual electrodes

Right-handed participants respond more quickly and more accurately to written words presented in the right visual field (RVF) than in the left visual field (LVF). Previous attempts to identify the neural basis of the RVF advantage have had limited success. Experiment 1 was a behavioral study of lateralized word naming which established that the words later used in Experiment 2 showed a reliable RVF advantage which persisted over multiple repetitions. In Experiment 2, the same words were interleaved with scrambled words and presented in the LVF and RVF to right-handed participants seated in an MEG scanner. Participants read the real words silently and responded "pattern" covertly to the scrambled words. A beamformer analysis created statistical maps of changes in oscillatory power within the brain. Those whole-brain maps revealed activation of the reading network by both LVF and RVF words. Virtual electrode analyses used the same beamforming method to reconstruct the responses to real and scrambled words in three regions of interest in both hemispheres. The middle occipital gyri showed faster and stronger responses to contralateral than to ipsilateral stimuli, with evidence of asymmetric channeling of information into the left hemisphere. The left mid fusiform gyrus at the site of the 'visual word form area' responded more strongly to RVF than to LVF words. Activity in speech-motor cortex was lateralized to the left hemisphere, and stronger to RVF than LVF words, which is interpreted as representing the proximal cause of the RVF advantage for naming written words.     

Interference processes in visual and olfactory stimulations

The aim of this work was to verify whether two congruent inputs (simultaneous administration of one odor and the corresponding name) increase recall or, on the contrary, whether recall becomes worse when there is no coincidence between the two simultaneous stimuli (verbal and olfactory). The data show no significant difference among the experimental conditions. It seems then possible to conclude that a 'visual dominance' effect takes place vis-á-vis the olfactory mode.     

PUNISHMENT AS DETERRENCE: REPLY TO SPRAGUE

In my 'A Deterrence Theory of Punishment', I argued that a deterrence system of punishment can avoid the charge that it illegitimately uses offenders if its punishments are carried out 'quasi-automatically': threats are issued by a legislature for deterrent purposes, but those who carry out the punishments have no authority to take deterrent considerations into account. Sprague has objected that under such a system, those who carry out punishments will be unable to justify their actions. I reply that if it is justifiable to set up the system in this way in the first place, then this justification will transmit to all actions carried out under it; and that it is justifiable to set up an institution of punishment in this way.     

Complementary and lateralized forms of processing in Bufo marinus for novel and familiar prey

Amphibian vision is one of the most comprehensively studied of all vertebrate sensory systems. However, the processes of object recognition and memory in anuran amphibians have resisted satisfactory explanation. Our research shows that insight to the issue of visual discrimination and recognition in toads may be gained by investigation of the specialized and complementary functions carried out by the left and right brain hemispheres. We report that specialized processes associated with the left eye (right hemisphere) of the Bufo marinus toad carry out decisions to view and strike at complex prey stimuli recognized as 'novel.' This was demonstrated in the toads' preferences when provided a choice between identical novel insect models presented simultaneously into the left and right lateral, monocular visual fields. In a second experiment, videotaped trials of toad groups competing in an open field for live crickets were analysed for lateralized prey-catching behaviour. Concomitant with a preference for directing agonistic strikes at conspecifics within the left visual hemifield, toads were found to possess a significant preference for directing predatory responses at the familiar prey viewed in the right visual hemifield. The preference for directing prey-catching responses at freely moving crickets in the right visual hemifield supports the earlier findings drawn from automated and familiar model insect prey. We present a hypothesis explaining differences in hemispheric processing in toads responding to 'novel' and 'familiar' prey types, utilizing a range of long-term memories found to be lateralized in other vertebrates.     

Laminar cortical dynamics of cognitive and motor working memory, sequence learning and performance: toward a unified theory of how the cerebral cortex works

How does the brain carry out working memory storage, categorization, and voluntary performance of event sequences? The LIST PARSE neural model proposes an answer that unifies the explanation of cognitive, neurophysiological, and anatomical data. It quantitatively simulates human cognitive data about immediate serial recall and free recall, and monkey neurophysiological data from the prefrontal cortex obtained during sequential sensory-motor imitation and planned performance. The model clarifies why spatial and non-spatial working memories share the same type of circuit design. It proposes how laminar circuits of lateral prefrontal cortex carry out working memory storage of event sequences within layers 6 and 4, how these event sequences are unitized through learning into list chunks within layer 2/3, and how these stored sequences can be recalled at variable rates that are under volitional control by the basal ganglia. These laminar prefrontal circuits are variations of visual cortical circuits that explained data about how the brain sees. These examples from visual and prefrontal cortex illustrate how laminar neocortex can represent both spatial and temporal information, and open the way towards understanding how other behaviors derive from shared laminar neocortical designs.     

How conscious experience and working memory interact

Active components of classical working memory are conscious, but traditional theory does not account for this fact. Global Workspace theory suggests that consciousness is needed to recruit unconscious specialized networks that carry out detailed working memory functions. The IDA model provides a fine-grained analysis of this process, specifically of two classical working-memory tasks, verbal rehearsal and the utilization of a visual image. In the process, new light is shed on the interactions between conscious and unconscious aspects of working memory.     

视觉预期的类型及神经机制

视觉预期是一种运用视觉信息的部分资源和先行资源对即将发生的事件进行预测的能力。为了人们更加清楚地认识视觉预期的内在加工过程,同时也有助于国内外研究者更为科学深入地探讨这种自上而下的加工,本文主要从婴幼儿和成人运动员两方面来阐述视觉预期的相关研究。首先从婴幼儿对物体相关属性和行为目标的视觉预期两方面探讨了视觉预期的类型,然后论述了成人视觉预期的神经机制。最后,指出今后的研究应加强视觉预期相关技术在临床诊断中的应用,注重环境在视觉预期中的作用,从神经网络角度研究视觉预期的神经基础。     

Visual attention as a multilevel selection process

Natural visual scenes are cluttered and contain many different objects that cannot all be processed simultaneously. Therefore, attentional mechanisms are needed to select relevant and to filter out irrelevant information. Evidence from functional brain imaging reveals that attention operates at various processing levels within the visual system and beyond. First, the lateral geniculate nucleus appears to be the first stage in the processing of visual information that is modulated by attention, consistent with the idea that it may play an important role as an early gatekeeper in controlling neural gain. Second, areas at intermediate cortical-processing levels, such as V4 and TEO, appear to be important sites at which attention filters out unwanted information by means of receptive field mechanisms. Third, the attention mechanisms that operate in the visual system appear to be controlled by a distributed network of higher order areas in the frontal and parietal cortex, which generate top-down signals that are transmitted via feedback connections to the visual system. And fourth, the pulvinar of the thalamus may operate by integrating and coordinating attentional functions in concert with the fronto-parietal network, although much needs to be learned about its functional properties. The overall view that emerges from the studies reviewed in this article is that neural mechanisms of selective attention operate at multiple stages in the visual system and beyond and are determined by the visual processing capabilities of each stage. In this respect, attention can be considered in terms of a multilevel selection process.