The proximodistal trend can be described as the direction of motor development.

The answer to the blank space is center-outward.

The proximodistal trend in general can be defined as a concept in developmental psychology where humans tend to develop more general functions of limbs before developing more specific fine motor skills – this is partially what the center to outward concept implies.

An example of this phenomenon would be how infants would learn how to use their arm before learning how to write.