The development of sustained visual attention in infants from 14 to 26 weeks of age.

The development of sustained visual allention was examined in Infants cross-seclionally at 14, 20, and 26 weeks of age. lIearl rate, hearl rate variablllt)., and respiralory sinus arrhythmia were measured in a S-min baseline period. Two methods for measuring ,'isual altention "'Cre used. The "infanl conlrol" method consisted of checkerboard presentations which were terminated when Ihe infanllooked awa)' from Ihem. The "interrupled slimulus" method consisted of a blinking panel in addition 10 the checkerboard palterns in order to altempt to actively terminate the lixation. The visual and cardiac responses during the inlerrupled stimulus method "'ere more highly correia led ".lth baseline respiratory sillus arrhylhmia than were the responses during the infant conlrol trials. The long latenc)' hearl rale responses during Ihe inlerrupled stimulus Irials showed a developmenlal change toward more mature response pallerns from 141026 weeks of age. It ma)' be concluded that: I) sllstained allenlion, measured with Ihe inlerrupled slimulus method, increases from 14 to 26 ,,'eeks of age; and 2) haseline respiralory sinus arrhylhmia is correlated with suslained allenlion respllnses and Iheir developmenl. DEscRllyroRS: Infancy, I leart rale, Resplralory sinus arrhylhmia, Visual allenlion, Suslained allention. crgic activity in Ihe ccnlral ncrvous systcm which inhibits ongoing behavior and allows the focusing of allenlion. This should be parlicularly Irue for "sustained" attention, which is subjccl-controlled, endogenous attenlion, occurring after Ihe firsl 5 10 6 seconds of "reactivc" attenlion, and which involves Ihe inhibilion of motor behavior. Individual differences in attention Iherefore could be indexed ifone had an adequate measure oflhe "cholinergic nervous systcm." II is Ihe case Ihal hearl rale variability occurring al the same frequency as rcspiralion, respiralory sinus arrhYlhmia, is largely produced by vagal efferenl inOuences on the heart (Anrep, Pascual, & Rossler, 1935; Kalona & Jih, 1975; Porges, McCabe, & Yongue, 1982). Sincc Ihe vagal control of the heart is mediated by acelylcholine, Ihe extenl of sinus arrhYlhmia is an index of the strength of the cholinergic syslem, and Iherefore should index individual differences in attention responses. Presumably, Ihis should not be limited to hearl rate responses, bul be related 10 other componenls of altenlion, such as lixation. One oflhe weaknesses oflhe studies lesling this Iheory with infants is Ihe lack of a good measure of sustained visual attenlion. Previous sludies of infanl visual attention have used eilher fixed duration trials or Ihe infanl conlrol procedurc 10 de409 Heart rate variabililY, particularly variability due \0 respiratory sinus arrhythmia, is known to index Ihe a\tenlional responsivity ofinfanls. Several sludies wilh newborn infants (e.g., Porges, 1974; Porges, Arnold, & Forbes, 1973; Porges, Slamps, & Waller, 1974; Vranekovic, rHock, Isaac, & Cordero, 1974; Williams, Schacler, & Tobin, 1967) have shown Ihal hearl rale responses 10 psychological slimulation occur more often and with grealer slrenglh in infants with greater variabililY in heart rale. More recenlly, Richards (1985) found Ihallhe slrength of respiralory sinus arrhythmia recorded during a baseline period was associaled wilh the slrenglh of the heart rale decelerative response during visual a\tenlion in 14 and 20 week old infanls. It was even the case in Ihat study Ihat more mature visual Iixation duralions were correia led with the exlenl of sinus arrhylhmi;l measured during Ihe baseline condilion. An explanation for the relationship between heart rale variability and a\tenlional responses has been offered by Porges (Porges, 1976, 1980). 1\ is argued Ihat a\tention processes arc facililaled by cholinAddress requests for reprints to: John E. Richards, Departmenl of Psychology, University of Soulh Carolina, Columbia, SC 29208. '"