Diana Martella

Minimizing sleep deprivation effects in healthy adults by differential outcomes.

Sleep deprivation reduces vigilance or arousal levels, affecting the efficiency of certain cognitive functions such as learning and memory. Here we assessed whether the differential outcomes procedure (DOP), a learning procedure that has proved useful to ameliorate episodic memory deficits, can also improve memory performance in sleep-deprived participants. Photographs were presented as sample faces. A probe face was then presented for recognition after either short or long delays. In the differential outcomes condition a unique reinforcer followed correct responses. In the non-differential outcomes condition reinforcers were provided in a random manner. The results indicated that the DOP prevented the recognition memory to decrement during the long delay in the control group, replicating previous findings. The sleep-deprived group showed DOP benefits mainly with the short delay, when working memory could be affected by low arousal. These findings confirm that the DOP can overcome impaired recognition memory due to sleep deprivation conditions.

Efficiency and interactions of alerting, orienting and executive networks: The impact of imperative stimulus type

The Attention Network Test (ANT) generates measures of three attention networks: alerting, orienting and executive control. Arrows have been generally used as imperative stimuli in the different versions of this paradigm. However, it is unknown whether the directional nature of these stimuli can modulate the efficiency of the executive control and its interaction with alerting and orienting. We developed three ANT variants to examine attentional effects in response to directional and non-directional stimuli. Arrows (ANTI-A), colored fruits (ANTI-F) and black geometrical-shape (ANTI-G) were used as imperative stimuli (i.e., flanker stimuli). Data collected from fifty-two university students, in two experiments, showed that arrows stimuli produced a greater interference effect and a greater orienting effect as compared to the other stimuli. Moreover, only arrows modulated the interaction between executive control and orienting: a reduced flanker effect in spatially cued trials was only observed in ANTI-A. These results suggest that the directional value of the stimuli increases the conflict and modulates the efficiency of executive control and its interaction with orienting network.

The effects of endogenous and exogenous spatial cueing in a sustained attention task

Sustained attention is the ability to maintain the focus of cognitive activity on a given stimulation source or task over an extended period of time (Ballard 1996). Experiments on sustained attention have been conducted using specific tasks, such as the continuous performance task (CPT), which requires subjects to monitor a continuous presentation of symbols, detecting critical signals (e.g. the letter ‘‘X’’) occurring infrequently or randomly, and inhibiting any response to distracters (Rosvolt et al. 1956). The CPT allows measuring both the vigilance level and the vigilance decrement through the increase of response time (RT) over trials. Prolonged performance in attentional tasks is thought to deplete the pool of involved resources, in particular when controlled processes are employed, as these resources are limited in their availability (Davies and Parasuraman 1982). However, it is not clear how this depletion occurs, nor what is the nature of the attentional resources employed (Matthews et al. 2000). Vigilance has been ascribed to the control of top-down processes, which would not enable sustaining performance during prolonged tasks (Smit et al. 2004). However, a strict distinction between controlled and automatic processes cannot be usually made (Folk et al. 1992). Although exogenous and endogenous attentional processes are extensively investigated by studies on visuospatial selective attention using short lasting tasks, the involvement of automatic and controlled processing in sustained attention is still unclear. For example, Posner (1980) showed that both these attentional processes can be elicited using a spatial cueing paradigm. In this paradigm, subjects are required to detect a target which is presented to the right or to the left of a fixation point. The target is preceded by a spatial cue indicating the likely location of target appearance. The attentional orienting can be guided by a central symbolic cue (endogenous orienting), but attention can also be attracted by peripheral stimuli (exogenous orienting). It is traditionally maintained that endogenous orienting is voluntary and requires conscious awareness (Bartolomeo et al. 2007), whereas exogenous orienting operates as an automatic process (Ivanoff and Klein 2003). The aim of the present study was to investigate the involvement of both endogenous and exogenous attentional processing during a task implying a decrease of sustained attention. To this end, we devised a new experimental paradigm, the continuous attentional orienting task (CAOT), resulting by a combination of the CPT and the spatial cueing paradigm. This novel task allowed the examination of how a manipulation of exogenous and endogenous attention modulates sustained attention. We presented two versions of the task: in the endogenous task, a geometric figure was used for central cueing; a peripheral uninformative change of brightness was the cue in the exogenous task. Exogenous and endogenous cues may influence sustained attention in different ways. If sustained attention requires controlled processes depleting attentional resources, one can expect the endogenous task to be more vulnerable to deterioration. On the other side, exogenous cues may improve sustained attention because of the alerting effect of a sudden change in the periphery of the visual field (Fernandez-Duque and Posner 1997). M. Sebastiani (&) M. Casagrande D. Martella A. Raffone Department of Psychology, University ‘Sapienza’ of Rome, Rome, Italy e-mail: mara.sebastiani@yahoo.it

Hemispheric modulations of the attentional networks

Although several recent studies investigated the hemispheric contributions to the attentional networks using the Attention Network Test (ANT), the role of the cerebral hemispheres in modulating the interaction among them remains unclear. In this study, two lateralized versions of this test (LANT) were used to investigate theal effects on the attentional networks under different conflict conditions. One version, the LANTI-A, presented arrows as target and flankers, while the other version, the LANTI-F, had fruits as target and flankers. Data collected from forty-seven participants confirmed well-known results on the efficiency and interactions among the attentional networks. Further, a left visual field advantage was found when a target occurred in an unattended location (e.g. invalid trials), only with the LANTI-F, but not with LANTI-A. The present study adds more evidence to the hemispheric asymmetry of the orienting of attention, and further reveals patterns of interactions between the attentional networks and the visual fields across different conflicting conditions, underlying the dynamic control of attention in complex environments.

Visual Search and Emotion: How Children with Autism Spectrum Disorders Scan Emotional Scenes

This study assessed visual search abilities, tested through the flicker task, in children diagnosed with autism spectrum disorders (ASDs). Twenty-two children diagnosed with ASD and 22 matched typically developing (TD) children were told to detect changes in objects of central interest or objects of marginal interest (MI) embedded in either emotion-laden (positive or negative) or neutral real-world pictures. The results showed that emotion-laden pictures equally interfered with performance of both ASD and TD children, slowing down reaction times compared with neutral pictures. Children with ASD were faster than TD children, particularly in detecting changes in MI objects, the most difficult condition. However, their performance was less accurate than performance of TD children just when the pictures were negative. These findings suggest that children with ASD have better visual search abilities than TD children only when the search is particularly difficult and requires strong serial search strategies. The emotional–social impairment that is usually considered as a typical feature of ASD seems to be limited to processing of negative emotional information.

Inhibition of return: a "depth-blind" mechanism?

When attention is oriented to a peripheral visual event, observers respond faster to stimuli presented at a cued location than at an uncued location. Following initial reaction time facilitation responses are slower to stimuli subsequently displayed at the cued location, an effect known as inhibition of return (IOR). Both facilitatory and inhibitory effects have been extensively investigated in two-dimensional space. Facilitation has also been documented in three-dimensional space, however the presence of IOR in 3D space is unclear, possibly because IOR has not been evaluated in an empty 3D space. Determining if IOR is sensitive to the depth plane of stimuli or if only their bi-dimensional location is inhibited may clarify the nature of the IOR. To address this issue, we used an attentional cueing paradigm in three-dimensional (3D) space. Results were obtained from fourteen participants showed IOR components in 3D space when binocular disparity was used to induce depth. We conclude that attentional orienting in depth operates as efficiently as in the bi-dimensional space.