Cremasco, M

Folegatti, Alessia

Gindri, P.

Neppi-Modona, Marco

Pia, Lorenzo

Spinazzola, L

English

NEPPI-MODONA, Marco

Institutional Research Information System University of Turin

Monday, April 14, 1:00 - 3:00 pm Poster Session F176 Cognitive Neuroscience Societyphysiological evidence for processing of task-irrelevant faces, even underhigh perceptual load which usually prevents distractor processing.F5ATTENTIONAL MODULATION OF STIMULUS APPEARANCE:ERP EVIDENCE FOR A POSTPERCEPTUAL PROCESS MichaelNiedeggen1; 1Experimental Psychology and Neuropsychology, Free UniversityBerlin, Germany — Numerous psychophysical studies indicated that atransient visuospatial shift of attention induced by a salient peripheralcue increases the apparent contrast of a target stimulus. Here, a similarcuing paradigm was used to examine the effect of covert attention on theappearance of visual motion coherence: A short sequence of coherence(100 ms) was embedded in two dynamic random dot kinematograms(RDK) presented left and right of a fixation. Subjects had to decide whichRDK was apparently defined by a higher level of coherence. The targetwas preceded by a short reduction in luminance in one RDK serving as acue (SOA: 100 ms). Psychophysical data revealed that the apparentmotion coherence was reduced by an invalid cue (higher coherence in thecontralateral RDK), and attenuated by a valid one (higher coherence inthe ipsilateral RDK). A corresponding modulation of the event-relatedbrain potentials (ERPs) was obtained in the range of a late cognitive com-ponent (P300), but not within the negativity associated with sensorymotion processing (N200). Here, invalid cues were found to prolong thetime course of sensory processing. The results indicate that reflexiveattention does not necessarily enhance a visual signal, and that the corre-sponding shift in stimulus appearance reflects the activation of a postper-ceptual process.F6A LOWER LOADED HEMISPHERE AIDS IRRELEVANTPROCESSING Ritsuko Nishimura1, Kazuhito Yoshizaki1, Kimiko Kato1,Takeshi Hatta2; 1Aichi Shukutoku University, 2Nagoya University — Ourstudy aimed to investigate whether or not a distractor was processed inthe hemisphere which is loaded with the lower perceptual load. Thisquestion was motivated by the assumption that each hemisphere has anindependent resource. Right-handed 16 participants were asked to dis-criminate a target letter in briefly presented five task-relevant letters,while ignoring a distractor presented in the periphery outside the task-relevant letters. We manipulated perceptual load of the target (high-loador low-load), presentation mode between a target and a distractor(within- or across-field), and compatibility of a target and a distractor(compatible or incompatible). In the high-load condition, a target andthree non-target letters were presented in either left (LVF) or right visual-field (RVF) and a non-target letter was presented in the opposite visual-field. In the low-load condition, a target was presented in either LVF orRVF and four non-target letters were presented in the opposite visual-field. In the within-field condition, the target and the distractor were pre-sented in the same visual-field. By contrast, in the across-field condition,they were presented in the divided visual-fields. Results showed that inthe low-load condition the compatibility effect was larger in the within-field condition than in the across-field condition. On the contrary in thehigh-load condition, the compatibility effect was larger in the across-fieldthan in the within-field condition. These results suggested that the dis-tractor was processed in the hemisphere which was loaded with lowerperceptual load, irrespective of the presentation mode.F7TEMPORAL EXPECTANCY INFLUENCES ORIENTING IN TIMEBUT NOT THE TIME COURSE OF ORIENTING IN SPACE NathanParks1, Paul Corballis1; 1Georgia Tech — It has long been known that atten-tion may be oriented to regions of visual space. More recently, it has beenproposed that attention may also be directed to instants in time. That is,an endogenous cue of attention may carry information regarding thetemporal validity of an upcoming target. In the case of both spatial andtemporal orienting, endogenous cues must be informative and the cue-target validity of these cues must be learned. We wondered whether thetime course of spatial orienting is learned and is dependent on the tempo-ral validity of endogenous spatial cues. We examined interactionsbetween temporal orienting and the time course of spatial attention bybiasing cue-target stimulus onset asynchrony (SOA) in an endogenousspatial attention paradigm. Subjects (N=72) performed an endogenousspatial cuing task (75% validity) with cue-target SOAs 100, 200, 300, 400,500, 600, or 700 ms. The temporal validity of spatial cues was manipu-lated between groups by weighting the occurrence of one SOA over theothers. In the three groups (N=24), the validity of 100, 400, or 700 ms wasmanipulated by weighting the corresponding SOA to occur 40% of thetime versus the 10% occurrence of each remaining SOA. Simple reactiontime data were examined for interactions between spatial and temporalorienting. There were significant within-subjects effects of spatial orient-ing and significant between-subjects effects of temporal orienting, but nointeraction between the two. Results are consistent with the idea that spa-tial and temporal orienting operate via separable mechanisms.F8BEHAVIORAL AND ELECTROPHYSIOLOGICAL LINKSBETWEEN DRD4 AND ATTENTION ORIENTING IN CHILDRENKoraly Perez-Edgar1, Nathan Fox2, Louis Schmidt3; 1George Mason University,2University of Maryland, College Park, 3McMaster University — Numerousstudies have shown that the D4 dopamine receptors (DRD4s) play impor-tant roles in attentional and motivational processes. With children, muchof the focus has been on Attention-Deficit/Hyperactivity Disorder(ADHD). Less work has focused on the role of DRD4 in normal develop-ment. In the current study, we examined the links between DRD4 allelicstatus and performance in a standard measure of attention orienting, thePosner cued-attention paradigm, in 7-year-old children. Building on pre-vious work, the Posner task was modified to include a baseline, affect-neutral, condition and a second condition completed in an emotionally-charged environment. The impact of this manipulation on attention ori-enting was examined using behavioral (RT) and psychophysiological(ERP) measures. The children with the long-allele (LA) were significantlyslower in the task than their peers in the short-allele (SA) group, F(1,47)=8.57, p<.01. The LA group was particularly slow when presentedwith invalidly cued trials, F(1, 47)=6.59, p=.01, across both neutral andaffective conditions. For the N1 component, children in the SA groupshowed the expected validity effect, which increased from the neutral toaffective Posner condition. However, the LA group displayed a decreasein the validity effect across conditions, F(1, 43)=4.85, p=.03. For N2, theLA group had smaller peak amplitudes and failed to show the validityeffect in the affective task, F(1, 43)=7.61, p=.01. The data indicate that chil-dren with the long allele have greater difficulty with basic attention-ori-enting processes, perhaps contributing to the link between DRD4 andattention problems, including ADHD.F9MENTAL IMAGERY AND VISUAL PERCEPTION OF THE MENTALNUMBER LINE Lorenzo Pia1,2, Alessia Folegatti1, Marco Neppi-Mòdona1,2,Luigi Cremasco3, Lucia Spinazzola1,4, Patrizia Gindri5; 1University of Turin,2Neuroscience Institute of Turin (NIT), University of Turin, 3Fondazione DonCarlo e Centro Santa Maria ai Colli, Turin, 4Hospital Company S. AntonioAbate, Gallarate, 5San Camillo Hospital, Turin — It has been suggested arelationship between spatial thinking and number representation, suchthat numbers are represented along a continuous, left-to-right mentalnumber line with smaller quantities located to the left of larger ones.Some evidence comes from the joint deficits of space and numbers pro-cessing in left-neglect patients. These patients, when required to indicatewhich number is halfway between two orally presented numbers thatdefine a numerical interval, may displace the midpoint progressivelyrightwards as the interval grows. This raises the question of whethershifting attention within a mental representation produces a correspond-ing attentional shift in the visual field, and vice-versa. To address thisquestion, we selected 10 neglect patients with the aforementioned patternof numerical error. The same numerical intervals were then employed ina “numerical-endpoint task” that consisted of two conditions: 1) MarkingCognitive Neuroscience Society 177Poster Session F Monday, April 14, 1:00 - 3:00 pmthe midpoint of the empty space enclosed between two numericalextremes; 2) Same as 1), but now patients were asked to mark the mid-point by writing down the number that is numerically halfway betweenthe two numerical extremes. The results indicate that the size of numeri-cal intervals equally influenced the rightward numerical bias in the num-ber bisection and in the “numerical-endpoint” tasks. The same was nottrue for spatial bias (defined as the position of the bisector number): inthis case no modulation by the size of the numerical interval was present.These results suggest that attention shift across internal spatial represen-tation and external space might be underpinned by (at least some) differ-ent mechanisms.F10THE INFLUENCE OF REWARD AND PUNISHMENT ONATTENTION: EVIDENCE USING ERPS Nikki Pratt1, Dennis Molfese1;1University of Louisville — Event-related potentials (ERPs) investigatedthe influence of motivation and expectation on the neural processesinvolved in selective visual attention. The research design was adaptedfrom Derryberry & Reed’s (1994) paradigm. Cues preceded target loca-tion in peripheral boxes that contained positive or negative incentives.Points were awarded for a fast response in the positive incentive box andsubtracted for a slow response in the negative incentive box. The electro-physiological recordings utilized a 256-hydrocel electrode net to investi-gate valid and invalid targets in positive and negative boxes. The currentanalysis examined the ERP to targets with cues predicting target locationin 80% of the trials. Preliminary results indicated that the P1 in the occipi-totemporal region generated a larger response to trials with congruentcue and target locations. This was enhanced for targets that appeared inthe negative incentive box. The N1 in the occipitotemporal region gener-ated a larger response to incongruent cue and target locations. Specifi-cally, a greater N1 response occurred to invalid targets in the negativeincentive box. A cue presented in the positive incentive box followed by atarget in the negative incentive box generated the largest N1. The resultssuggest that early selective attention in the occipital cortex is influencedby motivation as well as target validity.F11THE RIGHT TIME AND THE LEFT TIME: SPATIALASSOCIATIONS OF ENDOGENOUS TEMPORAL CUES AFFECTTARGET DETECTION IN RIGHT BRAIN-DAMAGED PATIENTSCarson Pun1, Maha Adamo1, Ulrich W. Weger2, Sandra E. Black3, Susanne Ferber1;1University of Toronto, Canada, 2Keynes College, University of Kent, Canterbury,United Kingdom., 3L.C. Campbell Cognitive Neurology Research Unit,Neurosciences Research, Sunnybrook Health Sciences Centre, Canada — Rightbrain-damaged patients have slowed reaction times in detecting visualtargets presented on the contralesional (left) side of space when a priorcue is presented on the ipsilesional (right) side. Typically, the types ofcues used to demonstrate this are sudden onsets in the periphery leadingto exogenous shifts in attention. The role of endogenous cues, however, isstill unclear. Some studies have shown that endogenous processes can berelatively intact after right brain damage, though generally slowed. Wetested stroke patients with right hemisphere lesions on a spatio-temporalcueing task to see whether spatial associations of endogenous temporalcues would elicit the same cognitive deficits as do typical exogenouscues. An association between the representation of time and space hasbeen found in healthy subjects using a spatio-temporal cueing task withcentrally presented time words, such as “yesterday” or “future.” Suchtime cues are mapped onto a mental timeline that holds temporally ear-lier events on the left side of space and temporally later events on theright side. We administered a spatio-temporal cueing task to right brain-damaged patients and manipulated the spatial validity of a target follow-ing the central presentation of a time word. Our patients demonstratedthe greatest disengagement deficit for targets presented on the contrale-sional side of space when the centrally presented time word cued them tothe ipsilesional side. Our results indicate that the deficit in disengagingfrom invalidly cued locations persists for endogenous cues that elicit spa-tial mental representations.F12ATTENTION PLAYS A ROLE IN SUBITIZING: ANINATTENTIONAL BLINDNESS STUDY Henry Railo1,2, MikaKoivisto1,2, Antti Revonsuo1,2,3 Minna M. Hannula1,4; 1University of Turku,Finland, 2Centre for Cognitive Neuroscience, University of Turku, Finland,3School of Humanities and Informatics, University of Skövde, Sweden, 4SacklerInstitute for Developmental Psychobiology, Weill Medical College of CornellUniversity — Subitizing refers to the effortless process of enumeratingsmall numbers of items. Whether subitizing rests purely on parallel pre-attentive processeses, or, is actually an attention demanding process, hasbeen debated previously. Previous studies that have examined the atten-tional requirements of subitizing have based their conclusions on condi-tions where the participants have explicitly attended on the task ofenumeration and attention has been focused on the item location. Enu-meration latencies have also been shown to increase already in the sub-itizing range, suggesting that some serial, attentional components may beinvolved. The present study is the first that directly contrasts the preat-tentive and the attentive models of subitizing. We used inattentionalblindness paradigm to test whether enumeration is possible when theeffects of attention are minimized by presenting the items unexpectedlywhile the participants were focusing on another task. Divided- and full-attention conditions were also included. The results showed that onlynumbers one and two could be enumerated under inattention, that is,when the effects of attention were minimized. Moreover, freeing atten-tional resources in the divided- and full-attention conditions increasedthe enumeration accuracies considerably, including for number two.Thus, the results suggest that even for enumerating small numbers, theattentional demands increase as the number of objects increases.F13EVENT-RELATED POTENTIAL INDICES OF ASYMMETRIES INATTENTIONAL GRADIENTS John C. Richiedei1, William Bush1, LisaD. Sanders1, Kyle Cave1; 1University of Massachusetts, Amherst — Previousevidence suggests that if the possible locations of stimulus presentationare delineated, spatial attention affects processing in a graded manner.Specifically, stimuli presented close to cued regions elicit larger visualevoked potentials (VEPs) than those presented farther away. However,both position in the visual field and allocation of attention may contributeto the observed gradients. These relative contributions can be distin-guished by comparing responses on physically identical trials whenattention is directed to locations at various distances from the stimuli. Inthe current study, participants attended to one of 12 squares arranged ina circle around fixation. Letters appeared individually, each in one of thesquares; 80% were O’s (standards) and 20% were X’s (deviants). Partici-pants pressed a button when an X appeared at the attended location.VEPs elicited by standards showed evidence of asymmetric attentionalgradients. Specifically, the largest amplitude N1s were observed whenparticipants attended to the location where a standard was presented.Responses were also larger to standards when attention was directlyabove the stimulus compared to when it was directly below. However, allof these conditions resulted in larger amplitude N1s than when partici-pants were attending to more distant locations. These results confirm thatattention can be applied to visual processing in a spatial gradient andreveal its asymmetric distribution.F14DEFICITS IN EARLY DETECTION AND DISCRIMINATIONPROCESSES OF ATTENTION DURING NICOTINEABSTINENCE Anthony Rissling1, Dana Smith1, Irene Yang1, MichaelDawson1, Anne Schell2, Keith Nuechterlein3; 1University of Southern California,2Occidental College, 3University of California Los Angeles — Impaired perfor-mance during continuous performance tasks (CPTs) has been reliablyreported in smokers following nicotine abstinence when compared tonicotine intake. However, the specific processes of attention that account

Mental imagery and visual perception of the mental number line

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Mental imagery and visual perception of the mental number line

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