Page:Mind (Old Series) Volume 11.djvu/555

554 J. JASTROW: THE PERCEPTION OF SPACE, ETC. ing Table the number of errors in 10 judgments and the average confidence are recorded as in the former Table. |.Moli<m(Ann).l S|>;m(II;iml)- I Absolute Length : 100 mm. Absolute Length : 25 mm. Difference of ;,). Difference ofyoo- Difference of - 5 V. Difference of -,,',0. No. of errors in 10. Av. con- fidence. No. of errors in 10. Av. con- fidence. No. of errors in 10. Av. con- fidence. No. of errors in 10. Av. con- fidence. Seeing.. Blind... 1-3 5 58 1-84 3'5 2-2 27 1-56 1-2 9 65 1-77 3.3 2'4 20 1-57 Seeing.. Blind... 3-2 1-6 19 1-39 ... ... 3'8 2-3 16 1-37 As in seeing persons, the sense of Span has a finer sensibility than that of Motion. In both senses the blind show a marked supe- riority over the seeing. 1 By his thumb and forefinger the blind person can appreciate quite as fine distinctions as the seeing person by sight. Moreover, the confidence of the former is unusually high, indicating a reliance on these senses unknown to the latter. Conclusion. A reference to the classification of the Space-senses will show how small a portion of the problem has been investigated. Only one in each of the three most disparate methods of gaining linear impressions has been experimented upon. However, the method of experimentation employed is equally applicable to the others (and with some modifications to the study of the Time-sense). Very possibly future research in this direction will greatly supplement and modify the conclusions above reached, although these are based on no less than 28,000 observations, extending over a period of eighteen months. My thanks are due to the very many persons who in various ways kindly gave up their time to the interests of this rather extended research. Hiiltimore, Jan. 1886. 1 The fact that the discriminative sensibility of the blind is finer luit their error in reproducing sensations larger than that of seeing persons, indicates that these two kinds of faculty do not go together. This is borne out by the fact that those individuals who make the greatest error in reproducing sensations are able to judge fine differences as well as or better than others.