Multisensory spatial representations in eye-centered coordinates for reaching

Humans can reach for objects with their hands whether the objects are seen, heard or touched. Thus, the position of objects is recoded in a joint-centered frame of reference regardless of the sensory modality involved. Our study indicates that this frame of reference is not the only one shared across sensory modalities. The location of reaching targets is also encoded in eye-centered coordinates, whether the targets are visual, auditory, proprioceptive or imaginary. Furthermore, the remembered eye-centered location is updated after each eye and head movement. This is quite surprising since, in principle, a reaching motor command can be computed from any non-visual modality without ever recovering the eye-centered location of the stimulus. This finding may reflect the predominant role of vision in human spatial perception.     

Evaluation of an inference-based approach to treating obsessive-compulsive disorder

This study evaluated an inference-based approach (IBA) to the treatment of obsessive-compulsive disorder (OCD) by comparing its efficacy with a treatment based on the cognitive appraisal model (CAM) and exposure and response prevention (ERP). IBA considers initial intrusions in OCD (e.g. "Maybe the door is open", "My hands could be dirty") as idiosyncratic inferences about possible states of affairs arrived at through inductive reasoning. In IBA such primary inferences represent the starting point of obsessional doubt, and the reasoning maintaining the doubt forms the focus for therapy. This is unlike CAM, which regards appraisals of intrusions as the maintaining factors in OCD. Fifty-four OCD participants, of whom 44 completed, were randomly allocated to CAM, ERP or IBA. After 20 weeks of treatment all groups showed a significant reduction in scores on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the Padua Inventory. Participants with high levels of obsessional conviction showed greater benefit from IBA than CAM. Appraisals of intrusions changed in all treatment conditions. Strength of primary inference was not correlated with symptom measures except in the case of strong obsessional conviction. Strength of primary inference correlated significantly with the Y-BOCS insight item. Treatment matching for high and low conviction levels to IBA and CAM, respectively, may optimize therapy outcome.     

Is evidence for late selection due to automatic or attentional processing of stimulus identities?

This study determined whether evidence for late selection is due to attention processing or to processing by an automatic system that is separate from attention (two systems framework; Eriksen, Webb, & Fournier, 1990). The task was a two-choice discrimination of a target that appeared in one of two sequentially cued locations in an eight-letter visual display. Attention was directed to the first cued location (cue 1), and whether identification processing occurred at a different location before the second cue (cue 2) directed attention there was determined. Cue validity varied across two experiments, and critical trials were those in which the target appeared at cue 2. For these trials, the target was preceded by a letter (either identical, neutral, or incompatible) that changed to the target at various time intervals following cue 2. Automatic identification was assumed if the incompatible letter interfered with response to the target when it appeared only before cue 2 onset and independent of cue validity. The incompatible letter appearing only before cue 2 onset interfered with the target when the target occurred equally often at cue 1 and cue 2, but not when the target occurred at cue 1 70% and at cue 2 30% of the time. This disconfirms the two systems framework and suggests that attention is required for spatial form processing and response competition.     

The persistence of a misconception about vision after educational interventions

Children and adults, like many ancient philosophers, believe that seeing involves emissions from the eye. Several experiments tested the strength of these “extramission” beliefs to determine whether they, like other scientific misconceptions, are resistant to educational experiences. Traditional college-level education had little impact. Presenting a simplified lesson, stressing visual input, and a lesson directly counteracting the vision misconception had an impact, but for older participants the effect was evident only on short-term tests. Despite some gain due to learning, overall the results demonstrated the robustness of extramission beliefs.     

Conjunction benefits and costs reveal decision priming for first-order and second-order features

Across two experiments, decision priming was examined for conjunctions composed of first-order or first- and second-order stimulus features. Observers indicated the presence or absence of one or two features in a Gabor stimulus. When a pair of stimulus features differed in their speed of discrimination, responses indicating the presence of a conjunction were faster than those for the single feature for which discrimination was slowest (conjunction benefits). Also, responses indicating the absence of a conjunction were delayed if one of the features was present (conjunction costs). These results show that first- and second-order features can prime decisions about the presence of a conjunction and suggest that the two kinds of signals can be combined at a decision stage after the discrimination of stimulus properties has begun for each system.     

ERPs associated with visual duration discriminations in prefrontal and parietal cortex

An event-related potentials (ERP) study was undertaken to examine the role of prefrontal and parietal association cortices on selective attention and short-term memory functions in a duration discrimination task. Subjects performed better when discriminating the first stimulus relative to the second and not the reverse. Two contingent negative variations (CNV) were obtained for each stimulus duration at prefrontal regions, as well as two P300s at parietal regions. The CNV(S1) component recorded during the first stimulus (S1) appeared to be involved in selective attention at bilateral sites, while the P300(S1) component in the left hemisphere may be implicated in retaining it. The CNV(S2) wave, displayed during the second stimulus (S2), at bilateral sites and the right-sided P300(S2) wave seem to be implicated in working memory. The results indicate that recorded activity at prefrontal and parietal association cortices is tightly linked to task parameters and behavioral performances.     

The contribution of private and public information in foraging by Australasian gannets

Predators that forage on foods with temporally and spatially patchy distributions may rely on private or public sources of information to enhance their chances of foraging success. Using GPS tracking, field observations, and videography, we examined potential sites and mechanisms of information acquisition in departures for foraging trips by colonially breeding Australasian gannets (Morus serrator). Analyses of the bill-fencing ceremony between mated pairs of breeding gannets did not detect correlations between parameters of this reciprocal behavior and foraging trips, as would have been predicted if gannets used this behavior as a source of private information. Instead, 60 % of the departing birds flew directly to join water rafts of other conspecific en route to the feeding grounds. The departure of solitary birds from the water rafts was synchronized (within 60 s) with the arrival of incoming foragers and also among departing birds. Furthermore, solitary departing birds from the rafts left in the same directional quadrant (90º slices) as the prior arriving (67 %) and also prior departing forager (79 %). When associated plunge dives of conspecific were visible from the colony, providing a public source of information, gannets more often departed from the water rafts in groups. Our study thus provides evidence for the use of water rafts, but not the nest site, as locations of information transfer, and also confirms the use of local enhancement as a strategy for foraging flights by Australasian gannets.     

The Leuven Perceptual Organization Screening Test (L-POST), an online test to assess mid-level visual perception

Neuropsychological diagnostic tests of visual perception mostly assess high-level processes like object recognition. Object recognition, however, relies on distinct mid-level processes of perceptual organization that are only implicitly tested in classical tests. The Leuven Perceptual Organization Screening Test (L-POST) fills a gap with respect to clinically oriented tests of mid-level visual function. In 15 online subtests, a range of mid-level processes are covered, such as figure–ground segmentation, local and global processing, and shape perception. We also test the sensitivity to a wide variety of perceptual grouping cues, like common fate, collinearity, proximity, and closure. To reduce cognitive load, a matching-to-sample task is used for all subtests. Our online test can be administered in 20–45 min and is freely available at www.gestaltrevision.be/tests. The online implementation enables us to offer a separate interface for researchers and clinicians to have immediate access to the raw and summary results for each patient and to keep a record of their patient’s entire data. Also, each patient’s results can be flexibly compared with a range of age-matched norm samples. In conclusion, the L-POST is a valuable screening test for perceptual organization. The test allows clinicians to screen for deficits in visual perception and enables researchers to get a broader overview of mid-level visual processes that are preserved or disrupted in a given patient.     

An enhanced experimental procedure to rationalize on the impairment of perception of action capabilities

It is well documented that changes in the physiological states of the perceiver–actor influence the perception of action capabilities. However, because experimental procedures of most studies involved a limitless availability for stimuli visual encoding and perceptual strategies, it remains difficult to adopt a single position among the large range of alternative interpretations for impaired perception. A reaching-to-grasp paradigm under breathing restriction was adapted from Graydon et al. (Cogn Emot 26:1301–1305, 2012) to standardize the time for encoding of stimuli information and narrowed the involvement of perceptual strategies. In the present study, we propose a highly controlled environment where the discrete information is presented during 300 ms, congruently with neurophysiological studies focused on visuomotor transformation. An underestimation of the perception of action capabilities is found under breath restriction, suggesting that 300 ms for stimuli encoding is sufficient to induce altered visuomotor brain transformations when limiting the involvement of perceptual strategies. This result suggests that such behavior could refer to an impaired brain potentiation of the perceptual occurrence, providing strong hypotheses on the brain dynamics of sensorimotor integration that underlie impaired perception of action capabilities in stressful situations.     

Preschoolers use phrasal prosody online to constrain syntactic analysis

Two experiments were conducted to investigate whether young children are able to take into account phrasal prosody when computing the syntactic structure of a sentence. Pairs of French noun/verb homophones were selected to create locally ambiguous sentences ([la petite ferme ] [est très jolie] ‘the small farm is very nice’ vs. [la petite] [ ferme la fenêtre] ‘the little girl closes the window’ – brackets indicate prosodic boundaries). Although these sentences start with the same three words, ferme is a noun (farm) in the former but a verb (to close) in the latter case. The only difference between these sentence beginnings is the prosodic structure, that reflects the syntactic structure (with a prosodic boundary just before the critical word when it is a verb, and just after it when it is a noun). Crucially, all words following the homophone were masked, such that prosodic cues were the only disambiguating information. Children successfully exploited prosodic information to assign the appropriate syntactic category to the target word, in both an oral completion task (4.5‐year‐olds, Experiment 1) and in a preferential looking paradigm with an eye‐tracker (3.5‐year‐olds and 4.5‐year‐olds, Experiment 2). These results show that both groups of children exploit the position of a word within the prosodic structure when computing its syntactic category. In other words, even younger children of 3.5 years old exploit phrasal prosody online to constrain their syntactic analysis. This ability to exploit phrasal prosody to compute syntactic structure may help children parse sentences containing unknown words, and facilitate the acquisition of word meanings.