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Prenatal Exposure to Temporal and Spatial Stimulus Properties Affects Postnatal Responsiveness to Spatial Contiguity in Bobwhite Quail Chicks

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Prenatal Exposure to Temporal and Spatial Stimulus Properties Affects Postnatal Responsiveness to Spatial Contiguity in Bobwhite Quail Chicks
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  Prenatal Exposure to Temporaland Spatial Stimulus PropertiesAffects Postnatal Responsivenessto Spatial Contiguity inBobwhite Quail Chicks* Mark JaimeRobert Lickliter Department of Psychology, Infant Development Research Center, FloridaInternational University, Miami, FL 33199 E-mail: licklite@fiu.edu   ABSTRACT:  Little is known about how experiential factors guide and organize thedevelopment of intersensory perception. This study manipulated the amount of late prenatal and early postnatal experience with the temporal synchrony and spatialcontiguity of audio–visual stimulation available to bobwhite quail embryos and hatchlings to explore this question. Results revealed that only embryos exposed totemporally synchronous and spatially contiguous audio–visual stimulation prior to hatching subsequently preferred spatially contiguous audio–visual maternalinformation following hatching, despite being denied postnatal visual experience. In contrast, embryos that did not receive exposure to both temporal synchrony and spatial contiguity (and were also denied postnatal visual experience) failed to showa preference for the spatial contiguity of maternal auditory and visual information following hatching. These results suggest that prenatal exposure to the amodal properties of temporal synchrony and spatial contiguity facilitate chicks’ emergingsensitivity to the spatial contiguity of audio–visual information in the period  following hatching.   2006 Wiley Periodicals, Inc.  Dev Psychobiol 48: 233–242,2006.  Keywords:  perceptual development; intersensory perception; prenatal sensoryexperience; spatial contiguity INTRODUCTION How young organisms respond to the temporal andspatial features of sensory stimulation has receivedincreasing research attention in both the neural and psy-chological sciences (Calvert, Spence, & Stein, 2004). Incontrast to the large body of work on human infants’capacity to perceive temporally based intersensoryrelations (see Lewkowicz, 2000 for a review), relativelyfewstudieshaveinvestigatedtheroleofspatialcontiguityin the development of intersensory perception. The fewstudies that have investigated infants’ responsiveness tospatial information present a mixed set of results, butdo suggest that younger infants have a relatively hightolerance for audio–visual spatial discrepancy and thatthis tolerance for spatial discrepancy appears to decreasewith age (see Field, 1987; Morrongiello, 1994 foroverviews).Morrongiello and her colleagues (Fenwick & Morron-giello,1998;Morrongiello,1994;Morrongiello,Fenwick,& Nutley, 1998) have proposed that infants are initiallymore sensitive to temporal elements of sensory stimula-tion in the weeks and months following birth, but that Received 19 May 2005; Accepted 7 September 2005*Portions of these data were presented at the International Societyfor Developmental Pyschobiology Annual Meeting, New Orleans,November, 2003. Correspondence to : R. LickliterContract grant sponsor: NIMHContract grant number: R01 MH62225Contract grant sponsor: NICHDContract grant number: R01 HD048423Published online in Wiley InterScience(www.interscience.wiley.com). DOI 10.1002/dev.20131  2006 Wiley Periodicals, Inc.  spatialcontiguitycomestoplayanincreasinglyimportantrolein intersensoryintegration with additional perceptualexperience. In support of this view, they providedevidence that spatial contiguity becomes more salientover the course of development, with 6- and 8-month-oldinfants exhibiting a lower tolerance for audio–visualspatial disparity when compared to younger 2-and 4-month-old infants. For example, younger infants asso-ciatedsynchronousobjectsandsoundsdespitesubstantialviolations in spatial contiguity, whereas older infants didnot (Morrongiello et al., 1998). Bahrick and Lickliter(1998)obtainedevidencethatconvergedwiththefindingsof Morrongiello et al. (1998). Specifically, 2.5-, 3.5-, and4.5-month old infants demonstrated a developmentaltrend of increased sensitivity to spatial contiguity infor-mationwithincreasingagewhenpresentedwithtwoside-by-sidefilmsofmovingobjectsandthematchingauditorystimulus to one of the objects emanated from a remotespatial location. Two and a half month-old infants weretolerant of spatial disparity when the audio–visual infor-mation was temporally synchronized. However, the 3.5-and 4.5-month old infants required greater spatialcontiguity to relate the auditory and visual information.Although not yet examined systematically, this develop-mental trend of a greater demand for spatial contiguity of auditory and visual stimulation is likely the result of infants’ongoingexperienceinthemonthsfollowingbirthwith multimodal objects and events whose sights andsounds emanate from the same location at the same time.Studies that manipulate the amount or type of sensoryexperience involved in the development of intersensoryintegration are, however, difficult to undertake withhuman infants and comparative research using animalsubjects offers a useful approach to investigate theseissues. A wide variety of studies of nonhuman animalinfants have shown sensitivity to temporal and spatialinformation during early development (see Lewkowicz &Lickliter, 1994; Lickliter & Bahrick, 2000, for reviews).Sincemostanimalinfantsareabletowalksoonafterbirthorhatching(anddonotrequirerestraintinaninfantseatasdo human subjects in perception research), comparativeinvestigators have capitalized on movement and proxi-mity seeking behaviors to investigate infants’ sensitivityto the spatial contiguity of bimodal stimulation.For example, Lickliter, Lewkowicz, and Columbus(1996) utilized the bobwhite quail chick to examine theeffects of early postnatal sensory experience on theneonate’s responsivenessto the spatialcontiguity of audi-tory and visual sensory stimulation. This study assessedwhether the amodal property of spatial contiguity wouldhave developmental priority over modality-specific sti-mulus properties. Amodal stimulus properties are thosecommon to more than one sensory modality (Gibson,1969; Gibson & Pick, 2000). For example, temporalsynchrony and spatial contiguity are both amodal proper-ties present in multimodal events. In contrast, modality-specific properties are those available only to one sensorymodality, such as color or pitch. Also of interest waswhether chicks’ sensory experience during the periodbetweenhatchingandtestingcontributedtotheirabilitytorespond to the spatial contiguity between sights andsounds. Results of this study revealed that quail chickspreferred a nonconspecific scaled quail hen colocatedwith a bobwhite quail maternal call over a spatiallydisparate(butspecies-specific)bobwhitehen orbobwhitematernal call. A subsequent study showed that chicksdenied normal patterns of postnatal auditory or visualexperiencewiththeirsiblingsfollowinghatching,showedalackofapreferenceforspatialcontiguityovermodality-specific features when compared to unmanipulatedcontrol chicks (Columbus, Sleigh, Lickliter, & Lewko-wicz, 1998), suggesting the importance of postnatalsensory experience in the development of sensitivity tospatial features of bimodal stimulation. To further extendour understanding of the development of auditory-visualintegration, the present study focused on the influence of experience with temporal and spatial features of sensorystimulation during prenatal development on subsequentpostnatal responsiveness to spatial features of sensorystimulation.Theprenatalenvironmentprovidesanarrayofongoingsensory stimulation to the developing embryo or fetus(Lickliter, 2000, 2005), raising the interesting question asto whether prenatal experience with temporally and/orspatially integrated features of multimodal stimuli mightplay a role in the emergence of intersensory responsive-ness during early postnatal development. The notion thatprenatal experience with temporally and spatially inte-grated properties could contribute to the emergence of intersensory development seems plausible when oneconsiders the types of sensory stimuli that are typicallypresent in the prenatal milieu. For example, the move-ments and vibrations that accompany the sounds of speech, laughter, or sneezing produced by the mother canprovide temporally synchronous and spatially contiguousbimodal (i.e., auditory and tactile/vestibular) stimulationto the human fetus. Likewise, bird embryos can receivetemporally synchronous and spatially contiguous vestib-ular and auditory stimulation when their maternal henvocalizes as she sits on her clutch of eggs. Do these typesof prenatal experiences contribute to the neonate’semerging responsiveness to spatially contiguous multi-modal events or is it the case that infant responsiveness tospatialcontiguity isbased whollyonpostnatal experiencewith integrated multimodal stimulation?To begin to address this question, the present studyutilized bobwhite quail embryos and hatchlings to assesswhether prenatal exposure to temporally synchronous Developmental Psychobiology. DOI 10.1002/dev  234  Jaime and Lickliter   and spatially contiguous audio–visual information couldbias bobwhite quail chicks’ preferences for unifiedaudio–visual stimuli (spatial contiguity) over modality-specificauditoryorvisualstimulation (call orhen) duringearly postnatal development. Given that several studieswith human infants have suggested that the temporaland spatial features of audio–visual stimulation interactduring early periods of intersensory development (e.g.,Lawson, 1980; Lyons-Ruth, 1977), we were particularlyinterested in whether prenatal experience with bothtemporally synchronous and spatially contiguous audio–visual stimulation was necessary to promote postnatalintersensory responsiveness to spatial contiguity, or alter-natively, whether prenatal exposure to only temporallysynchronous or only spatially contiguous audio–visualstimulation would be sufficient to promote postnatalintersensory responsiveness. GENERAL METHODS Certainfeatures ofthis experimentaldesign were common to allexperiments.Thesefeaturesaredescribedfirstbeforedescribingthe particular details of each experiment. Subjects Subjects were 120 incubator-reared bobwhite quail chicks( Colinus virginianus ). Fertilized unincubated eggs werereceived weekly from a commercial supplier and set in a BSS-160 Grumbach Incubator maintained at 75–80% relativehumidity and 37.5  C. Embryonic age was calculated on thebasis of the first day of incubation as Day 0, second day of incubationasDay1,andsoon.Tocontrolforpossiblevariationsin developmental age, only those birds that hatched on Day 23were used as subjects. Subjects were drawn from two or moredifferent batches of eggs to control for possible between-batchvariation in behavior. Following hatching, groups of 15–20 subjects were reared in a ventilated light-attenuated rearingbox until time of testing. Chicks had continuous access to foodand water. Ambient air temperature was maintained atapproximately 30  C. Apparatus Approximately24hrpriortohatching,embryosweretransferredto a sound attenuated stimulation room and placed in a Model1602N Hova-Bator portable hatcher, maintained at approxi-mately 37.5  C and 80% relative humidity. This hatcher allowedembryos to receive audio–visual stimulation via a transparentplastic window located directly above the embryos. Audio–visual stimulus presentations (described below) were deliveredvia a custom-designed software program running a Proxima2810desktopprojectorlocated22cmdirectlyabovetheportablehatcher window and a speaker placed on top of a small hole onthe top of the hatcher, immediately adjacent to the window.Postnatal behavioral tests took place in an arena 130 cm indiameter, surrounded by a wall 60 cm in height. The arenasurface was painted flat black and the walls of the testing arenawere insulated with a special layer of foam to attenuatereverberation. The arena walls were covered with an opaqueblack curtain. Avideo camera mounted directly above the arenaallowed for remote observation and data collection. Three semi-circular approach areas, each comprising approximately 5% of the total area of the testing arena, were demarcated on a remotevideo monitor (these were not marked on the testing arena’ssubstrate). Two of the three approach areas contained a 4-inchspeaker mounted to the arena wall and hidden behind the black curtain (to allow for auditory stimulation). Both speakers werepowered by separate RCA SA-155 integrated stereo amplifiersand the auditory stimuli were played by two Sony CDP-XE370compact disk players. Taxidermically prepared models of anadult bobwhite quail hen were placed in the appropriateapproach areas (to provide visual stimulation). Ambient roomtemperature was maintained between 29  and 32  C. Procedure Bobwhite quail embryos were divided into three experimentalconditions: (1) the Temporally Synchronous and SpatiallyContiguous Group was exposed to an individual variant of thebobwhite maternal call concurrently with a pulsing lighttemporally synchronized with the notes of the call for 10 min/ hrduringthe24hrpriortohatching(thepositionofthelightandcall were spatially contiguous). The auditory component of thestimulus consisted of a call burst of five notes with a complexrhythmic pattern. The duration of the burst was 3 s (rate of notesaveraged1.7notes/s)andwasfollowedbyaninter-burstintervalof 1 s. The notes of the call varied in duration, intensity, andfundamentalfrequency.Temporalsynchronyoftheauditoryandvisual stimulation was achieved by recreating the temporalpatterning of the maternal auditory call in the visual componentof the stimulus (the patterned light) and presenting the call andlight simultaneously. This presentation was controlled by acomputer program specifically designed to temporally coincidethe auditory and visual stimuli (see Lickliter, Bahrick, &Honeycutt,2002).(2)ATemporallyAsynchronousandSpatiallyContiguous Group was exposed to the same maternal callpresented concurrently with a pulsing light out of synchronywith the notes of the call (the position of the light and call werealso spatially contiguous). The patterned light pulsed at aconstantratethatdidnotcoincidewiththetemporalpatterningof the maternal call. (3) ATemporally Synchronous and SpatiallyDisparateGroupwasexposedtothesamesynchronizedauditoryand visual stimuli as the Temporally Synchronous and SpatiallyContiguousGroup,however,thespeakerpresentingthematernalcall was spatially separated from the pulsing light by 60 cm.Because this study focused on prenatal experiential factors,the possible contribution of chicks’ postnatal experience withintegrated auditory and visual stimulation was controlled byrearingallsubjectsindarknessfromhatchingtotesting.Previousresearch has shown that dark-reared chicks fail to demonstratepreferential responsiveness to spatial contiguity in the daysfollowing hatching (see Lickliter et al., 1996). Thus, by rearingDevelopmental Psychobiology. DOI 10.1002/dev  Prenatal Exposure to Temporal and Spatial Properties  235  chicks in darkness in the present study, any preferences forspatial contiguity during subsequent postnatal testing wouldsuggest that prenatal sensory experience with temporal syn-chrony and/or spatial contiguity is sufficient to facilitate chicks’responsiveness to spatial contiguity during early postnataldevelopment. Testing Testing consisted of a 5 min (300 s) simultaneous-choice testbetween (1) a stuffed adult bobwhite quail hen spatiallycontiguous with an unfamiliar bobwhite incidental call, (2) astuffed bobwhite hen, and (3) an unfamiliar incidental callspatially separated by 60 cm. Thus, chicks could respond to asilent bobwhite hen, an incidental call, or the bobwhite henspatially colocated with the same call (see Fig. 1). Since thebobwhite incidental call (see Heaton, Miller, & Goodwin, 1978,foracoustical details) and the bobwhite hens used during testingwere novel, this procedure required chicks to respond based ontheir preferences for (a) audio–visual spatial contiguity, (b)modality-specific visual cues, or (c) modality-specific auditorycues, rather than on familiarity with the test stimuli. The soundintensity of each call was adjusted to peak at 65 dB, measuredfrom the start box where each chick was introduced into thearena. The locations of the hens and calls presented duringtestingwerecounterbalancedacrossindividualtrialstopreventapossible side bias from affecting results.Eachchickwastestedonlyonce.Chickswerescoredonboththeir latency of approach and the duration of time they spent ineach of the three approach areas by an observer blind to theexperimental condition. Latency was defined as the amount of time(inseconds) thatelapsedfromtheonset ofthetrialuntilthechick entered an approach area. Duration was defined as thecumulativeamountoftime(inseconds)thechickremainedinanapproach area. Any chick that did not enter any approach areareceived a score of 300 s for latency (i.e., the length of the trial)and 0 s for duration and was considered a nonresponder. Thesechicks were excluded from subsequent analyses. A preferencefor a given stimulus was scored if a chick stayed in an approachareaforat leasttwice thetime spentinopposingapproach areas.No preference for a stimulus was scored if a chick approachedtwoorthreeareasduringatrialbutdidnotspendatleasttwiceasmuch time in one approach area as the other. These measures of preference constituted the primary dependent variable. AVisualBasic computer program allowed semi-automated collection of latency and duration of response to the test stimuli. Data Analysis The data of interest in each experiment were the measures of preference for the auditory and visual stimuli presented duringthe testing trials. Several measures were analyzed: (1) differ-ences in the latency of initial response and (2) duration of timespent in each approach area by subjects in a group. These scoreswerecomparedbytheWilcoxonmatched-pairssigned-rankstestto determine whether latency and duration scores for one stimu-lus differed from that of the others within a condition. (3) Themeasure of primary interest was the individual preference score(usedinanumberofpriorstudiesofperceptualdiscriminationinbobwhite quail, see Lickliter & Hellewell, 1992; Lickliter &Lewkowicz, 1995 for examples), assigned to any chick thatstayedinoneareaformorethantwiceaslongaseitherotherarea.These preferences were evaluated by the chi-square goodness-of-fit test to determine if subjects in a condition showed asignificant preference for any test stimulus presented in thethree-choicetest.Significancelevelsof   p < .05(two-tailed)wereused to evaluate all results.We utilized nonparametric tests in the present study forseveral reasons. Previous studies of bobwhite quail usingmethods comparable to those reported here have shown thatchicks’responselatencyanddurationscoresinthesimultaneouschoice test vary widely within an experiment and acrossexperiments (e.g., Lickliter & Hellewell, 1992; Lickliter &Lewkowicz, 1995; Lickliter et al., 2002). The data from thepresent experiments showed similar patterns of variance. Thewide range of scores obtained when measuring latency andduration of response make measures of central tendency hard tointerpret. Nonparametric statistics are preferable under theseconditions (Thorne & Giesen, 2000). EXPERIMENT 1: EFFECTS OF PRENATALEXPOSURE TO TEMPORAL SYNCHRONYAND SPATIAL CONTIGUITY ON POSTNATALRESPONSIVENESS TO SPATIAL CONTIGUITY Previous research has demonstrated that bobwhite quailembryos are sensitive to auditory and visual stimulipresented during late prenatal development and that thetypes of audio–visual stimulation available to bobwhite Developmental Psychobiology. DOI 10.1002/dev FIGURE 1  Top view of the behavioral testing arena. (a) Areacontaining the spatially contiguous hen and call, (b) areacontaining only the incidental call, (c) area containing only thehen, (d) area used for counterbalancing the position of the areacontaining only the hen.  236   Jaime and Lickliter   quail embryos can have varying effects on perceptualresponsiveness,learning,andmemory(seeLickliter,2000for a review). For example, when bimodal audio–visualstimulation is presented concurrently but out of syn-chrony, it can interfere with prenatal perceptual learning(Gottlieb, Tomlinson, & Radell, 1989; Honeycutt &Lickliter, 2001; Lickliter & Hellewell, 1992; Radell &Gottlieb, 1992). In contrast, prenatal exposure to bimod-ally redundant and temporally synchronous (amodal)audio–visual stimuli appears to facilitate perceptuallearning and enhance memory during the late prenatalperiods (Lickliter et al., 2002; Lickliter, Bahrick, &Honeycutt,2004).Thesestudieshaveexposedembryostotemporally synchronous or temporally asynchronousaudio–visual stimulation and assessed how these tem-poralconfigurationsaffectchicks’abilitytorecognizeandprefer an individual maternal call they were exposed toprenatally.In this experiment, embryos were exposed to tempo-rally synchronous and spatially contiguous audio–visualstimulation during late prenatal development and theirpostnatal responsiveness to the spatial contiguity of unfamiliar audio–visual stimuli was assessed. In otherwords, we did not assess perceptual learning but ratherwhetherchicks’responsivenesstothespatialcontiguityof audio–visual stimulation over modality-specific featuresof maternal stimulation would be affected followingprenatal exposure to temporal synchrony and spatialcontiguity. Method Sixty bobwhite quail embryos, divided into two groups,served as subjects. Embryos from Group A ( n ¼ 30) didnot receive prenatal exposure and served as controls.Embryos from Group B ( n ¼ 30) were exposed to anindividual variant of a bobwhite maternal call and apatterned light temporally synchronized to the notes of the call (as described in the General Method section) for10 min per hour during the 24 hr prior to hatching.Subjects from both groups were transferred to a lightattenuatedrearingboxafterhatchingwheretheyremainedfor 72 hr. At 72 hr following hatching, all chicks receivedan individual simultaneous choice test between (a) aspatially contiguous maternal hen and bobwhite inciden-tal call, (b) a bobwhite hen alone, and (c) an incidentalbobwhite call alone. Results and Discussion AsillustratedinFigure2,embryosthatdidnotreceiveanysupplemental prenatal stimulation (Group A), and weredarkrearedfromhatchingtotesting,didnotdemonstrateasignificantpreferenceforthespatiallycontiguoushenandcalloverthehenaloneorcallalone, w 2 (2,  N  ¼ 20) ¼ .400;  p ¼ .819. Analyses of the latency scores from Group A(Tab. 1) showed a significant difference between the areacontaining the hen and the area containing the call,  z ¼ 2.012,  p ¼ .044.However,nosignificantdifferencesin duration scores between the spatially contiguous henand call, the call, and the hen alone were found. Incontrast,embryos exposedto the temporallysynchronouslight and call (Group B) significantly preferred thespatially contiguous hen and call over both the hen aloneand the call alone,  w 2 (2,  N  ¼ 27) ¼ 9.00;  p ¼ .029.Analysis of latency scores did not reveal significantdifferences between the spatially contiguous hen andincidental call, the hen, or the call. However, there weresignificantdifferencesindurationofresponsebetweenthespatially contiguous hen and call and the call alone,  z ¼ 2.595,  p ¼ .009(Wilcoxontest).Further,the  p -valuefor the difference in duration scores between the spatiallycontiguous hen and call and hen approached statisticalsignificance,  z ¼ 1.898,  p ¼ .058 (Wilcoxon test). Theseresults suggest that prenatal exposure to temporal syn-chrony and spatial contiguity biased chicks’ responsive-ness to spatial contiguity during postnatal testing, despitethe fact that subjects were reared in darkness and deniedongoing spatially contiguous audio/visual experiencefrom hatching to testing.One possible explanation for these results is thattemporal synchrony and spatial contiguity are amodalstimulus properties and prenatal experience with theseamodal properties somehow fostered embryos’ respon-siveness to the amodal properties of auditory and visualevents during postnatal tests. Previous work has demon-strated that embryos exposed to bimodal stimulationappeartoformanattentionalbiastowardsholisticfeaturesof bimodal stimulation and will demonstrate greaterresponsiveness to these features during postnatal tests(Honeycutt & Lickliter, 2002). In the present experiment, Developmental Psychobiology. DOI 10.1002/dev FIGURE 2  Preferences of chicks at 72 hr following hatchingexposed to prenatal bimodal temporal synchrony and spatialcontiguity and controls in Experiment 1. Prenatal Exposure to Temporal and Spatial Properties  237 
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