Global/local processing and negative priming: the influence of selection difficulty and stimulus exposure

Negative priming is a decrement in performance observed when a previously ignored stimulus is re-presented as a target. The present study examined the relation between selection difficulty and negative priming in five experiments that used hierarchical stimuli (large letters made up by small letters). The results show that negative priming is greater when subjects direct attention to the local level (more difficult selection) than when they direct attention to the global level (less difficult selection). However, that occurs only when exposure of prime and probe is sufficiently long. With shorter presentations, negative priming is still observed but is no longer modulated by selection difficulty. These results suggest that both anticipatory and reactive mechanisms are responsible for the occurrence of negative priming and that instantiation of the reactive mechanism depends on the time available for prime and probe selection. Received: 17 January 2000 / Accepted: 3 July 2000     

Drawing perseveration in neglect: Effects of target density

In cancellation tasks, patients with unilateral spatial neglect typically fail to mark targets within the side of the sheet contralateral to the side of the lesion (contralesional). Moreover, they can show a perseverative behaviour, which consists in repeatedly cancelling stimuli, mainly in the side of the display ipsilateral to the side of the lesion (ipsilesional). We investigated in 13 right‐brain‐damaged patients with left spatial neglect and perseverative behaviour whether and how different densities of horizontal targets modulated omission and perseverative errors. We found that the density of targets modulated the patients’ distribution of neglect (area of omission), but not its extent, as indexed by the percentage of omissions. Specifically, the area of omissions tightened when target density increased leftwards. On the other hand, target density did not affect the distribution of perseverative behaviour (area of perseveration), as well as its extent, as indexed by the percentage of perseverations. Correlation analyses showed that both the extent and the distribution of omissions were positively correlated to clinical measures of spatial neglect. Conversely, perseverations did not show such a correlation. These findings support the view that two different pathological mechanisms might be involved in left spatial neglect and in ipsilesional perseverative behaviour.     

Visual object agnosia without prosopagnosia or alexia: Evidence for hierarchical theories of visual recognition

Abstract

A single case study is presented of a patient, Mr. W, with a selective deficit in recognizing pictures and real objects, linked to impaired stored visual knowledge about objects. Despite this, Mr. W maintained a preserved ability both to read aloud printed words and to recognize famous faces, when compared with age-matched control subjects. In addition, his access to semantic information from words was superior to that from pictures. The data provide evidence that visual agnosia can occur without alexia or prosopagnosia, contrary to recent proposals (Farah 1990, 1991). This finding is consistent with a hierarchical model of visual object recognition in which agnosia can reflect impaired stored knowledge of objects without accompanying perceptual deficits. The selective recognition deficit for objects further indicates that stored knowledge concerning different classes of visual stimuli (common objects, faces, and words) is separately represented in the brain.     

The effects of the presence of a face and direct eye gaze on voice identity learning

We rarely become familiar with the voice of another person in isolation but usually also have access to visual identity information, thus learning to recognize their voice and face in parallel. There are conflicting findings as to whether learning to recognize voices in audiovisual vs audio-only settings is advantageous or detrimental to learning. One prominent finding shows that the presence of a face overshadows the voice, hindering voice identity learning by capturing listeners' attention (Face Overshadowing Effect; FOE). In the current study, we tested the proposal that the effect of audiovisual training on voice identity learning is driven by attentional processes. Participants learned to recognize voices through either audio-only training (Audio-Only) or through three versions of audiovisual training, where a face was presented alongside the voices. During audiovisual training, the faces were either looking at the camera (Direct Gaze), were looking to the side (Averted Gaze) or had closed eyes (No Gaze). We found a graded effect of gaze on voice identity learning: Voice identity recognition was most accurate after audio-only training and least accurate after audiovisual training including direct gaze, constituting a FOE. While effect sizes were overall small, the magnitude of FOE was halved for the Averted and No Gaze conditions. With direct gaze being associated with increased attention capture compared to averted or no gaze, the current findings suggest that incidental attention capture at least partially underpins the FOE. We discuss these findings in light of visual dominance effects and the relative informativeness of faces vs voices for identity perception.     

Peer-Group and Romantic Relationships in Adolescents from Intact and Separated Families

The impact of family structure (intact vs. separated) on adolescents' friendship and romantic relationship were assessed, using an Italian representative sample of 300 adolescents. Findings reveal some significant differences related to family structure. Compared to adolescents from intact homes, adolescents from separated families display a higher level of distrust of others, are less likely to foresee marriage as a certain step in their lives, and show a higher degree of fear toward marriage. Contrary to expectations, there is no significant difference either in the extent and the frequency of contacts with the peer network or the existence of a romantic relationship among the two groups of adolescents. Implications are discussed.     

Causal Reasoning and Clinical Practice: Challenges from Molecular Biology

Not only has the philosophical debate on causation been gaining ground in the last few decades, but it has also increasingly addressed the sciences. The biomedical sciences are among the most prominent fields that have been considered, with a number of works tackling the understanding of the notion of cause, the assessment of genuinely causal relations and the use of causal knowledge in applied contexts. Far from denying the merits of the debate on causation and the major theories it comprises, this paper is meant as a stimulus for theorists of causation in the philosophy of biomedicine, with a focus on clinical matters. Without aiming at putting forward an original theory of causation and starting from the narration of two actual but paradigmatic cases at the joints between biomedical research and clinical practice, we want to point out that some pathological situations addressed by molecular medicine actually prove resistant to (at least) some of our major epistemological accounts of causal explanation. Given this scenario, which is very frequent in our hospitals, our analysis aims to provide a stimulus for the debate among theorists of causation in biomedicine interested in real cases in science in practice. We believe that this might in turn encourage some more general rethinking of the complex intertwinement of science, philosophy of science and ethics, as well as of the role of philosophy of science for clinical medicine itself.

     

Persistence of Traumatic Symptoms After Seven Years: Evidence from Young Individuals Exposed to the L’Aquila Earthquake

In this article, we investigated the presence of trauma-induced sequelae in a sample of 41 young individuals exposed to the L’Aquila earthquake who did not seek mental help in the aftermath of the disaster or in the ensuing months. We compared this group with 43 individuals, matched for age and education, who had not experienced an earthquake but had moved to and lived in L’Aquila after the earthquake and thus experienced the challenges of living in an earthquake-struck city. This study aimed to show that earthquake-exposed individuals scored significantly higher than nonexposed persons on certain scales of the Trauma Symptom Inventory (TSI) seven years after the event. Our results indicated that exposed individuals exhibited higher scores on the dissociation, intrusive experience, and defensive avoidance scales. Furthermore, a correlational analysis between specific conditions detected by the Earthquake Checklist L’Aquila (ECLA) and the TSI identified the influences of specific conditions, such as being trapped or injured under rubble during the earthquake, experiencing a persistent fear of aftershocks or a life-threatening feeling, and witnessing the death of a loved one. All of these experiences resulted in the persistence of trauma-related symptoms. Dissociative experiences during the trauma, cognitive and behavioral avoidance and reexperiencing were associated with negative effects and may hinder the natural process of recovery in trauma-exposed individuals. Knowledge of mid- and long-term psychological difficulties following a traumatic event may be useful for promoting interventions in mental health across exposed populations.     

The role of emotional context in facilitating imitative actions

In two experiments, we explored whether emotional context influences imitative action tendencies. To this end, we examined how emotional pictures, presented as primes, affect imitative tendencies using a compatibility paradigm. In Experiment 1, when seen index finger movements (lifting or tapping) and pre-instructed finger movements (tapping) were the same (tapping–tapping, compatible trials), participants were faster than when they were different (lifting–tapping, incompatible trials). This compatibility effect was enhanced when the seen finger movement was preceded by negative primes compared with positive or neutral primes. In Experiment 2, using only negative and neutral primes, the influence of negative primes on the compatibility effect was replicated with participants performing two types of pre-instructed finger movements (tapping and lifting). This emotional modulation of the compatibility effect was independent of the participants' trait anxiety level. Moreover, the emotional modulation pertained primarily to the compatible conditions, suggesting facilitated imitation due to negatively valent primes rather than increased interference. We speculate that negative stimuli increase imitative tendencies as a natural response in potential flight-or-fight situations.