Cortical modulation of visual contrast

Summary The mechanisms that produce simultaneous contrast have been thought to depend on retinal gain control and the retina is supposed to send signals to the brain only in terms of local-border contrast (Shapley, 1986). However, it was found that, when an object on a uniform background and border-concealing stimuli are presented to different eyes, the brightness of the object is greatly influenced if the border-concealing stimuli are perceptually superimposed on the border of the object. The change in the object's brightness in this condition is almost identical to that observed when both the object and the border-concealing stimuli are presented to the same eye, suggesting that the brain can compute brightness by using luminosity information when contrast information is disrupted.     

Rapid extraction of gist from visual text and its influence on word recognition

Two experiments explored rapid extraction of gist from a visual text and its influence on word recognition. In both, a short text (sentence) containing a target word was presented for 200 ms and was followed by a target recognition task. Results showed that participants recognized contextually anomalous word targets less frequently than contextually consistent counterparts (Experiment 1). This context effect was obtained when sentences contained the same semantic content but with disrupted syntactic structure (Experiment 2). Results demonstrate that words in a briefly presented visual sentence are processed in parallel and that rapid extraction of sentence gist relies on a primitive representation of sentence context (termed protocontext) that is semantically activated by the simultaneous presentation of multiple words (i.e., a sentence) before syntactic processing.     

Voluntary aspects of attentional control setting for detecting a feature‐defined target1

Abstract: Singleton targets that differ from distractors in a single salient attribute can be discerned regardless of the number of items in the display. Recent studies have indicated that the perception of singleton targets is facilitated by an attentional control setting. We focused on the voluntary aspect of the attentional control setting. Psychophysical and functional magnetic resonance imaging (fMRI) experiments examined the temporal characteristics of the attentional control setting by using an auditory cue. In both experiments, an auditorily cued feature‐search task was used. The cue validity (valid vs. neutral) and the cue lead time (CLT) were varied. In the psychophysical experiment, we established the effect of a symbolic cue on detection of a singleton. When the CLT was short or the cue was neutral, there was no facilitation, as re?ected by the slow activation of the attentional control setting. In our fMRI experiment, the brain activity indicates that this detection task activated the prefrontal cortex. These results demonstrate that the attentional control setting for facilitation of the singleton‐target perception modulates activity in regions of the prefrontal cortex.     

How do young children deal with hybrids of living and non‐living things: The case of humanoid robots

In this experiment, we tested children's intuitions about entities that bridge the contrast between living and non‐living things. Three‐ and four‐year‐olds were asked to attribute a range of properties associated with living things and machines to novel category‐defying complex artifacts (humanoid robots), a familiar living thing (a girl), and a familiar complex artifact (a camera). Results demonstrated that 4‐year‐olds tended to treat the category‐defying entities like members of the inanimate group, while 3‐year‐olds showed more variability in their responding. This finding suggests that preschoolers' ability to classify complex artifacts that cross the living–non‐living divide becomes more stable between the ages of 3 and 4 and that children at both ages draw on a range of properties when classifying such entities.     

Does scene context always facilitate retrieval of visual object representations?

An object-to-scene binding hypothesis maintains that visual object representations are stored as part of a larger scene representation or scene context, and that scene context facilitates retrieval of object representations (see, e.g., Hollingworth, Journal of Experimental Psychology: Learning, Memory and Cognition, 32, 58-69, 2006). Support for this hypothesis comes from data using an intentional memory task. In the present study, we examined whether scene context always facilitates retrieval of visual object representations. In two experiments, we investigated whether the scene context facilitates retrieval of object representations, using a new paradigm in which a memory task is appended to a repeated-flicker change detection task. Results indicated that in normal scene viewing, in which many simultaneous objects appear, scene context facilitation of the retrieval of object representations-henceforth termed object-to-scene binding-occurred only when the observer was required to retain much information for a task (i.e., an intentional memory task).     

Effector identity and orthogonal stimulus–response compatibility in blindness to response-compatible stimuli

Perceiving a visual stimulus is hampered when the stimulus is compatible with simultaneously prepared or executed action (blindness effect). We explored the roles of the effector identity of the responding hand and of orthogonal compatibility (above-right/below-left correspondence) in the blindness effect. In Experiment 1, participants conducted bimanual key presses with vertically arranged responses while perceiving a brief presentation of rightward or leftward arrowheads. A blindness effect based on the effector identity did emerge, but only with the above-right/below-left key-hand arrangement. An orthogonal blindness effect was not found in Experiment 2 with a horizontal key-press action task and a vertical arrowhead perception task. We concluded that the anatomical identity of the responding hand was not integrated into the action plan with an orthogonally incompatible key-hand arrangement. The findings are discussed in terms of the generality and limits of the blindness effect, and hierarchical response coding.     

The dynamic-stimulus advantage of visual symmetry perception

It has been speculated that visual symmetry perception from dynamic stimuli involves mechanisms different from those for static stimuli. However, previous studies found no evidence that dynamic stimuli lead to active temporal processing and improve symmetry detection. In this study, four psychophysical experiments investigated temporal processing in symmetry perception using both dynamic and static stimulus presentations of dot patterns. In Experiment 1, rapid successive presentations of symmetric patterns (e.g., 16 patterns per 853 ms) produced more accurate discrimination of orientations of symmetry axes than static stimuli (single pattern presented through 853 ms). In Experiments 2-4, we confirmed that the dynamic-stimulus advantage depended upon presentation of a large number of unique patterns within a brief period (853 ms) in the dynamic conditions. Evidently, human vision takes advantage of temporal processing for symmetry perception from dynamic stimuli.     

Determining the orientation of depth-rotated familiar objects

How does the human visual system determine the depth-orientation of familiar objects? We examined reaction times and errors in the detection of 15° differences in the depth orientations of two simultaneously presented familiar objects, which were the same objects (Experiment 1) or different objects (Experiment 2). Detection of orientation differences was best for 0° (front) and 180° (back), while 45° and 135° yielded poorer results, and 90° (side) showed intermediate results, suggesting that the visual system is tuned for front, side and back orientations. We further found that those advantages are due to orientation-specific features such as horizontal linear contours and symmetry, since the 90° advantage was absent for objects with curvilinear contours, and asymmetric object diminished the 0° and 180° advantages. We conclude that the efficiency of visually determining object orientation is highly orientation-dependent, and object orientation may be perceived in favor of front-back axes.