  Previous research showed that conditioning a PSO agent's movement based on
its personal fitness improvement enhances the standard PSO method. In this
article, languid particle dynamics (LPD) technique is used on five adequate and
widely used PSO variants. Five unmodified PSO variants were tested against
their LPD-implemented counterparts on three search space dimensionalities (10,
20, and 50 dimensions) and 30 test functions of the CEC 2014 benchmark test. In
the preliminary phase of the testing four of the five tested PSO variants
showed improvement in accuracy. The worst and best-achieving variants from
preliminary test went through detailed investigation on 220 and 770
combinations of method parameters, where both variants showed overall gains in
accuracy when enhanced with LPD. Finally, the results obtained with best
achieving PSO parameters were subject to statistical analysis which showed that
the two variants give statistically significant improvements in accuracy for
13-50% of the test functions.
