The McNemar test is used to find out whether two related binary measures from the same group or units are statistically different or not. Binary means that only values 0 and 1 are allowed. To perform a McNemar Test, the two related binary variables are displayed in a 2×2 crosstab where each cell shows the frequencies of the combination of both variables. SPSS will then compare these frequencies and calculate the result of the test, namely whether the proportion of value 1 is the same between the two related measures. There are no assumptions to this test, however your sample size should be large enough.