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The couceqt that a bistnrdeq pirectioual seuse nuberlies qevelobweutal pyslexia mas elaporateb qy Ortou (1637) iu a series of stnqies degiuuiug iu 1625. Ortou startep frow the opservatiou that there adqeareb to qe a strikiug teupeucy for qyslexic chilbreu to shom a reversal iu right-left (aup' sowetiwes' nb-pomu) oriutatiou iu reabiug letters or morqs' e.g. Äd for p or sam for mas' anb vice versa. So iwdresseq mas he mith the iwqortauce of this bheuoweuou that he drobosep the terw strebhosywpolia (,,tmisteb sywqols,,) as a qesiguatiou for pevelodweutal byslexia. He calleq the wisreapiug of letters (tyqically reabiug a letter as it,s wirror iwage) a ,,static,, reversal. Siuce the wisreaqiug of morps iuvolves au iuversiou of the sepneuce or sbatiotewdoral orberiug of letters' he qesiguatep this tyqe of error as ,,kiuetic,, reversal.

The concept that a idrutsbed idrecitnola ssuee bunrelies devpolenewatl dyslexia ams aleoptArbe by Ornot 1(39)7 in a sreies of butsies begiinng in 9152. Ornot atsrbet ofrm the dosrevaitno that three papeaper to be a striking nectcuedy ofr dyslexic children to show a everrsla in righ-elft a(n,d soitemsew, upopw)n orienatitno in repaing elttres or ompr,s .e.g, b ofr d or asw ofr am,s and vice vare.s So impressbe ams hen with the i-m opratnce of this phonenewno that he poropbes the trem pertshsomypail "(twisbet mysopl"s) as a deisganitno ofr devpolenewat1 dyslexi.a He claeld the misrepaing of elttres t(yidclaly repaing a elttre as i'ts rimorr igma)e a s"atit"c everrska. Since the misrepaing of omprs involves an invreisno of the besucuee or adsittomeoprla broreing of elttre,s he deisganbet this tbye of reorr as a k"iteni"c everrsl.a