Since 1991 Brooks has distinguished between situatedness and embodiment as two separate properties a machine or creature can have.

True: a Brooks publication dated 1991 (for example 'Intelligence Without Reason' or 'New Approaches to Robotics') defines situatedness and embodiment as distinct properties, and his later work keeps the distinction. Mostly true: the distinction appears in his published work no later than 1992, or in 1991 in slightly different form (the two concepts are clearly separated but not framed explicitly as 'either, neither, or both'). Mixed: he discussed both concepts in 1991 but without clearly separating them, and the explicit distinction comes several years later. Mostly false: the explicit distinction first appears well after 1991 (for example 1995 or later), and the 1991 work only touches on the ideas. False: his 1991 writings treat the two terms as the same thing, or neither concept appears in his work until much later.

Set before the research began.

1. E1 Intelligence Without Reason International Joint Conferences on Artificial Intelligence (IJCAI) · 1991 Own record

   “There are two reasons that embodiment of intelligent systems is critical. First, only an embodied intelligent agent is fully validated as one that can deal with the real world.”

2. E2 [PDF] New Approaches to Robotics - People | MIT CSAIL MIT CSAIL (author's hosted copy of 'New Approaches to Robotics' by Rodney A. Brooks) Own record

   “There are two subtly different central ideas that are crucial”

3. E3 cambrian intelligence - brooks Scribd (copy of Brooks, 'Cambrian Intelligence: The Early History of the New AI', MIT Press) · 1999 Own record

   “My work fits within the framework described above in terms of situatedness, embodiment, intelligence and emergence.”

4. E4 New Approaches to Robotics Author's MIT web page (people.csail.mit.edu/brooks); the page does not name the journal or give a date Own record

   “There are two subtly different central ideas that are crucial”

5. E5 Intelligence Without Reason International Joint Conferences on Artificial Intelligence (IJCAI) · 1991

   “PY - 1991”

6. E6 cambrian intelligence - brooks Scribd (copy of Brooks's 1999 MIT Press book Cambrian Intelligence) · 1999 Own record

   “Section 5 (Ideas) introduces the two cornerstones to the new approach to Artificial Intelligence, situatedness and embodiment, and discusses both intelligence and emergence in these contexts.”

7. E7 Intelligence Without Reason - Massachusetts Institute of Technology MIT (people.csail.mit.edu, Brooks's own paper page) Own record

   “Section 5 (Ideas) introduces the two cornerstones to the new approach to Artificial Intelligence, situatedness and embodiment, and discusses both intelligence and emergence in these contexts.”

8. E8 Intelligence Without Reason - Massachusetts Institute of Technology MIT (people.csail.mit.edu, Brooks's own paper page) Own record

   “The agents should be embodied as mobile robots, situated in unmodified worlds found around our laboratory27. This confronts the embodiment issue.”

9. E9 Intelligence Without Reason - Massachusetts Institute of Technology MIT (people.csail.mit.edu, Brooks's own paper page) Own record

   “when furniture is rearranged, when lighting or other environmental conditions change, and when their sensors and actuators drift in calibration. This confronts the situatedness issue.”

The IJCAI proceedings record dates 'Intelligence Without Reason' to 1991 (E6, E1). That paper names situatedness and embodiment as "the two cornerstones" of the new approach (E9). It also ties each to a separate principle: embodiment to agents built as mobile robots (E10), and situatedness to robots that keep working when the world around them changes (E11). His 1999 book still frames his work in terms of situatedness and embodiment (E4, E7). The available quotes show the two concepts clearly separated in 1991, but they do not show the paper's actual definitions or the explicit "either, neither, or both" framing, which matches the criteria for mostly true.