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Published on Mar 25, 2014
Direct perception: Ecological realism and perception-action - philosophical foundations. An invited philosophy department seminar given by Dr. PJ Treffner in New Zealand plus 30 mins Q & A. Time tags below.
Almost all theories of perception are a variant of the same theory: INDIRECT PERCEPTION. Supposedly, WE CAN NOT KNOW our world DIRECTLY. All we can "know" directly are physical, meaningless "sensations" at our body's sensory surfaces and then INFER ("perceive") a meaningful world that's "represented" inside our brain. Our awareness of "the world" is one step removed from reality! Thus, they say, we incorrectly believe we perceive the chair (a stance pejoratively called "naive realism") because a brain only has access to a retinal "image" and INFERS that a chair exists...we know nothing directly with certainty! We can only INDIRECTLY know (guess, infer) the world...they say.
Opposing this nonsense are serious, competent scientists from the tradition known as ECOLOGICAL PSYCHOLOGY. They promote a self-consistent theory based on modern scientific and empirical evidence, especially evolutionary theory and dynamical systems (complexity) theory. Philosophically, this approach argues for DIRECT PERCEPTION theory - that we CAN know our environments and apprehend the meaning of it DIRECTLY, without the assumption of internal mediation and a "neural representation". Brains are important, sure, but not sufficient.
Direct perception theory emphasises the need for (external) INFORMATION in the analysis. This was originator James Gibson's main point: perception is not based on sensations; it is based on information. Perception is not about images...it is about action and the awareness of AFFORDANCES - based on the detection of INFORMATION, not on the creation of internal models. This is exciting but difficult 21st Century science, not the simplistic 20th Century version of Cartesian dualism, and its variants. However, leading philosophers (eg, Searle - 1:01:08) now, finally, admit Gibson was in fact RIGHT.
00:55 - VIDEO - instability of perception 02:04 - cause of all the confusion - Descartes 04:36 - the nonsense of sensation-then-perception 07:38 - the assumed theory of perception 09:49 - the "argument" from illusion 12:19 - VIDEO - spinning ballet illusion 13:11 - illusions and importance of context 14:21 - illusions, retinal images, size constancy 15:08 - Gibson and texture gradient 17:19 - eye height information - (self) perception/size perception 19:01 - phenomenology...behaviourism...functionalism 21:12 - type-type vs. token-token identity theory 24:28 - problems of functionalism - "easy/hard problem" 30:40 - action and affordances - stair climbing 30:50 - VIDEO - climbing goats 31:07 - Warren's experiments on stair climbing 32:01 - maximum height perceivable? - results - scaling 33:29 - preferred height? 33:43 - preferred height: results - minimum energy 34:14 - preferred height perceivable? 34:28 - preferred height perceivable: results 35:01 - monument steps (and fail) 35:20 - affordances (Gibson): direct perception 37:54 - walking through doorways (Len Mark's research) 38:00 - walking through doorways: results 38:29 - passable doorway perceivable? 39:40 - other animals? (VIDEO during QT-Question Time) 41:33 - summary: Gibson's affordances and information 42:21 - information is detected; affordances are perceived 44:34 - VIDEO - motion information - occlusion 47:09 - VIDEO - now you see me now you don't! 47:23 - VIDEO - occlusion & point light displays 47:46 - summary - occlusion 48:58 - development and learning - kitten carousel 49:44 - EJ Gibson's visual cliff 50:58 - driving, optic flow, Gibson's field of safe travel 51:52 - VIDEO - optic flow (also during QT) 52:18 - VIDEO - our locomotion experiments 52:28 - moving room and vision for balance 52:44 - VIDEO - moving room (David Lee) (also during QT) 53:51 - VIDEO - artificial intelligence and affordances? 54:21 - indirect versus direct perception 55:07 - perception-action cycle 55:28 - driving inattention (phones) - our research 56:04 - the "hard problem"?-subjective consciousness?? 59:32 - the answer! 1:01:08 - VIDEO - Searle - Gibson: "I think he's on the right track" 1:03:05 - VIDEO - Searle - action fundamental for perception
-------- Question Time (with videos) --------
1:04:21 - Q. Misperception? VIDEO: optic flow 1:07:30 - VIDEO - optic flow driving (David Lee) 1:09:19 - VIDEO - moving room (full) 1:10:04 - Q. Innate perception vs. learning? 1:11:28 - VIDEO - climbing goats (full) 1:13:32 - VIDEO - Big Dog robot (full) 1:14:32 - Q. Does affordance change or perceiver change? 1:15:18 - VIDEO - animals' affordances - kea parrot 1:18:38 - Q. Virtual world affordances and "metaffordances"? 1:29:55 - Q. Was the (potential) affordance there before I existed?