528 J. M. CATTELL : As the determinations for the same letter were made at different times we find the mean variation larger than usual. Table XXXIII. gives besides the results obtained with aid of the sound- key, series made with aid of a second observer. The first observer simply named the letter as quickly as possible, and the second observer made the reaction on the sound in the manner above described. Mr. Wolfe acted as second observer ; in the Table I have subtracted his reaction-time on sound (150^) and his mean variation (10<r). TABLE XXXIII. Second Observer. 9. 30. I. Sound-Key. 5. 19. II. B C B C R V R' R V R' R V R' R V 11' A 398 444 466 421 400 432 453 435 395 408 432 412 421 429 410 459 446 422 431 425 428 463 421 465 433 431 25 30 36 18 11 31 31 20 26 29 18 20 44 38 15 64 28 20 33 25 22 32 42 46 20 12 405 436 477 417 402 434 446 441 403 417 438 418 400 419 404 442 461 435 431 432 434 460 4 05 471 in; 438 458 471 450 454 445 442 483 423 433 473 474 463 435 453 440 462 480 462 471 446 4(51 4(55 486 462 501 111!) 43 53 22 31 9 21 24 13 25 44 34 47 16 19 32 23 22 20 38 34 47 29 16 25 26 37 440 457 453 454 447 446 474 417 429 472 463 457 42.-> 460 436 4:..-) 469 469 479 454 471 401 481 460 493 507 430 414 417 394 396 405 402 356 394 399 395 393 389 384 395 392 428 385 391 398 391 383 363 381 405 393 18 26 88 61 30 30 48 20 24 42 25 22 2] 32 19 1!) 34 28 2~ 36 2-2 20 26 31 H 19 396 41 H; 417 400 397 412 395 352 394 410 101 3! 17 396 390 392 398 138 389 3!) 4 3!)() 3! Hi 378 364 388 415 392 462 418 421 1 1 2 ! 26 414
429 449 417 415 427 418 415 411 396 413 443 412 414 43!) 428 435 405 458 426 38 30 28 15 28 26 14 2G 36 21 27 34 2<> 36 16 16 22 18 22 18 14 26 24 29 33 2-2 476 413 424 411 424 420 426 422 451 415 409 423 422 422 409 393 418 446 410 409 441 423 132 412 463 421 B C D ... E . F G H I J K L M X
P Q E S T U V w X . . Y . . z A 430 431 461 459 395 396 424 424 AV 28 14 12!) 16 29 19 17 We thus see that it takes the observers about four-tenths of a second to see and name (/.e., read) a letter. In this connexion
