Halliday & Matthiessen (2014: 414):
As the examples illustrate, verbs of motion are phased temporally to indicate durative motion (‘continue to go’) and spatially to indicate directed motion (‘go’ + direction). With the second type, the verb often denotes some specific manner of motion such as flit and clamber in the examples above; the phrasal verb thus makes it possible to combine manner and direction: verb [manner] + adverb [direction]. Similar patterns are found in languages with ‘serial verb constructions’ and ‘verb compounding’. Direction occurs naturally with motion, of course; but it may also be used as a phasal extension verbs of other kinds, as with direction of perception:
Frodo and Sam gazed out in mingled loathing and wonder on this hateful land.
To be clear, on grammatical criteria, gaze and gaze out serve as behavioural Processes, not mental Processes of perception. For example, neither affords a Phenomenon — * gaze (out) this hateful land — but instead, like some other behavioural Processes, can take a Location circumstance that indicates the orientation of the behaviour, such as gaze (out) on this hateful land.