Here is an example of input for the SPSS procedure found under analyze:scale: multidimensional scaling. 

The input are pairs (i,j) of times of one subject to correctly respond to semantic category j immediately after identifying category i. The matrix is asymmetric and contains dissimilarities (the default) as higher RTs suggest more dissimilarity between a pair of stimuli.

||||||||||||||<14% style="TEXT-ALIGN: center"> '''stimulus''' ||<14% style="TEXT-ALIGN:center"> '''a'''||<14% style="TEXT-ALIGN:center"> '''b''' ||<14% style="TEXT-ALIGN:center"> '''c''' ||<14% style="TEXT-ALIGN:center"> '''d''' ||<14% style="TEXT-ALIGN:center"> '''e''' ||<14% style="TEXT-ALIGN:center"> '''f''' ||
||||||||||||||<14% style="TEXT-ALIGN: center"> '''a''' ||<14% style="TEXT-ALIGN:center"> 48 ||<14% style="TEXT-ALIGN:center"> 56 ||<14% style="TEXT-ALIGN:center"> 23 ||<14% style="TEXT-ALIGN:center"> 123 ||<14% style="TEXT-ALIGN:center"> 45 ||<14% style="TEXT-ALIGN:center"> 460 ||
||||||||||||||<14% style="TEXT-ALIGN: center"> '''b''' ||<14% style="TEXT-ALIGN:center"> 78 ||<14% style="TEXT-ALIGN:center"> 84 ||<14% style="TEXT-ALIGN:center"> 79 ||<14% style="TEXT-ALIGN:center"> 210 ||<14% style="TEXT-ALIGN:center"> 39 ||<14% style="TEXT-ALIGN:center"> 25 ||
||||||||||||||<14% style="TEXT-ALIGN: center"> '''c''' ||<14% style="TEXT-ALIGN:center"> 80 ||<14% style="TEXT-ALIGN:center"> 237 ||<14% style="TEXT-ALIGN:center"> 200 ||<14% style="TEXT-ALIGN:center"> 145 ||<14% style="TEXT-ALIGN:center"> 178 ||<14% style="TEXT-ALIGN:center"> 127 ||
||||||||||||||<14% style="TEXT-ALIGN: center"> '''d''' ||<14% style="TEXT-ALIGN:center"> 78 ||<14% style="TEXT-ALIGN:center"> 160 ||<14% style="TEXT-ALIGN:center"> 150 ||<14% style="TEXT-ALIGN:center"> 478 ||<14% style="TEXT-ALIGN:center"> 256 ||<14% style="TEXT-ALIGN:center"> 290 ||
||||||||||||||<14% style="TEXT-ALIGN: center"> '''e''' ||<14% style="TEXT-ALIGN:center"> 65 ||<14% style="TEXT-ALIGN:center"> 250 ||<14% style="TEXT-ALIGN:center"> 67 ||<14% style="TEXT-ALIGN:center"> 312 ||<14% style="TEXT-ALIGN:center">   4 ||<14% style="TEXT-ALIGN:center"> 345 ||
||||||||||||||<14% style="TEXT-ALIGN: center"> '''f''' ||<14% style="TEXT-ALIGN:center"> 410 ||<14% style="TEXT-ALIGN:center"> 340 ||<14% style="TEXT-ALIGN:center"> 312 ||<14% style="TEXT-ALIGN:center"> 324 ||<14% style="TEXT-ALIGN:center"> 367 ||<14% style="TEXT-ALIGN:center"> 367 ||

The code below, which may also be run from the menu, runs the multidimensional scaling procedure
specifying a 6x6 asymmetric matrix of user input for six stimuli and the ordinal level of measurement.

{{{
ALSCAL
  VARIABLES= a b c d e f
  /SHAPE=ASYMMETRIC
  /LEVEL=ORDINAL
  /CONDITION=MATRIX
  /MODEL=EUCLID
  /CRITERIA=CONVERGE(.001) STRESSMIN(.005) ITER(30) CUTOFF(0) DIMENS(2,2) .
}}}