tag:blogger.com,1999:blog-9192597712746432631.post8065201397728204312..comments2024-03-09T09:06:35.288+00:00Comments on Notes from Two Scientific Psychologists: Perceiving long distances in action scaled unitsAndrewhttp://www.blogger.com/profile/16732977871048876430noreply@blogger.comBlogger9125tag:blogger.com,1999:blog-9192597712746432631.post-75674172304708244612011-06-10T20:02:50.354+01:002011-06-10T20:02:50.354+01:00Strength is obviously part of the deal for executi...Strength is obviously part of the deal for executing a throw. But think of John McEnroe; little skinny guy with one hell of a serve. A big chunk of maximising release velocity is timing, not strength, and QBs are mainly big for other reasons. <br /><br />But this isn't about the act of throwing - it's about perception of affordances. People can perceive the affordance of an object's 'throwability to a maximum distance' if they have some level of throwing ability. Variation in that ability is not explained by any obvious body scale metric; therefore body scale (in terms of things like lengths of bits of you) isn't the action relevant variable used to scale <i>perception</i>. Body scale things like eye height units also probably won't do the trick for scaling the perception of distance, because they aren't obviously action related. However, we haven't run those studies yet.Andrewhttps://www.blogger.com/profile/16732977871048876430noreply@blogger.comtag:blogger.com,1999:blog-9192597712746432631.post-71327390227369654162011-06-10T16:42:34.406+01:002011-06-10T16:42:34.406+01:00Sorry, bad punctuation and a wrong word:
So, wit...Sorry, bad punctuation and a wrong word: <br /><br />So, within a limited range of physical differences, and given people who - based on body size and shape - are afforded the task, it is difficult to predict who DOES perform and who DOES not.Eric Charleshttps://www.blogger.com/profile/17412168482569793996noreply@blogger.comtag:blogger.com,1999:blog-9192597712746432631.post-20685131329289498622011-06-10T16:17:01.179+01:002011-06-10T16:17:01.179+01:00"If body scale variables aren't explainin..."If body scale variables aren't explaining performance, they clearly aren't the dimension along which performance is organised." <br /><br />I know Arther and Geoff's work a little, but obviously not as well as you do. In any case, this seems like an exaggeration. My four year old daughter cannot throw a football 60 yards, your average large, muscular NFL quarterback can. The physical differences between the quarterback and my daughter seem non-trivially related to throwing ability. <br /><br />So, within a limited range of physical differences, and given people who - based on body size and shape are afforded the task - it is difficult to predict who can perform and who cannot. Looking for good predictors in such a case is a perfectly good for an empirical research program. But if we don't frame the problem carefully I think it can lead to big confusion between (not within) research programs, and creates false problems in understanding how different projects fit together in a bigger whole (i.e., a coherent research field).Eric Charleshttps://www.blogger.com/profile/17412168482569793996noreply@blogger.comtag:blogger.com,1999:blog-9192597712746432631.post-19678553352100662042011-06-08T22:10:58.062+01:002011-06-08T22:10:58.062+01:00well... but lots of body scale parameters are rele...<i>well... but lots of body scale parameters are relevant to the affordance of throwing. </i><br />Such as? Geoff and Arthur have already tried a bunch related to hand span, etc, and none predicted judgements of the affordance. Effecting a throw is more about coordination between limb segments that simple sizes.<br /><br /><i>I suspect that most of the questions you are asking only make sense if we all already agree that our subjects can, in fact, perform the task.*</i><br />Ruling out people who cannot possibly effect the affordance for some straight forward reason, like quadriplegics, is ok by me. The ball does not afford throwing to them; their perception of the distance to the target is not scaled in locomotion or throwing scaled units.<br /><br /><i>Such investigations are really very straightforward to describe if we stick to body size, shape, etc.<br /><br />If we try to talk about "ability" in more sophisticated ways, I think it gets awfully hard to talk sensibly about what we are doing. </i><br />Straightforward does not equal true. If body scale variables aren't explaining performance, they clearly aren't the dimension along which performance is organised. Warren clearly got a bit lucky with stair climbing - leg length is a pretty good proxy for ability-to-raise-your-leg. There are no such obvious proxies for throwing. (I'll get more into this as I blog more on throwing, I think, a lot of this comes up in the papers by Arthur and Geoff.)Andrewhttps://www.blogger.com/profile/16732977871048876430noreply@blogger.comtag:blogger.com,1999:blog-9192597712746432631.post-24156526547358409002011-06-08T20:55:57.781+01:002011-06-08T20:55:57.781+01:00@ Gavin,
Yeah... embarrassing. Right after sending...@ Gavin,<br />Yeah... embarrassing. Right after sending that message I thought "Hey, haven't I seen talks in which lots of those manipulations were done. That might explain why I thought of them so quickly." I was hoping no one would notice.Eric Charleshttps://www.blogger.com/profile/17412168482569793996noreply@blogger.comtag:blogger.com,1999:blog-9192597712746432631.post-74860559346285664922011-06-08T20:15:51.593+01:002011-06-08T20:15:51.593+01:00well... but lots of body scale parameters are rele...well... but lots of body scale parameters are relevant to the affordance of throwing. It is certainly difficult, for example, for a quadriplegic. I suspect that most of the questions you are asking only make sense if we all already agree that our subjects can, in fact, perform the task.* So, the behavior IS afforded by the match between organism and environment: We then go on to study whether or not the afforded action is realized, and test hypotheses as to why certain afforded things happen while others do not. Such investigations are really very straightforward to describe if we stick to body size, shape, etc. <br /><br />If we try to talk about "ability" in more sophisticated ways, I think it gets awfully hard to talk sensibly about what we are doing. <br /><br /><br />*Unless you are specifically interested in threshold judgements, which are not as clean as the statistics make them seem either.Eric Charleshttps://www.blogger.com/profile/17412168482569793996noreply@blogger.comtag:blogger.com,1999:blog-9192597712746432631.post-31043582886051053182011-06-08T07:18:12.658+01:002011-06-08T07:18:12.658+01:00Eric, Gavin is right; Proffitt's group special...Eric, Gavin is right; Proffitt's group specialise in manipulating effort in exactly the ways you suggest. This paper uses the treadmill manipulation because it has been shown to have task specific results. <br /><br /><i>I'm increasingly suspicious of this approach. On the one hand, it is clearly true. On the other hand, I'm worried that the ecological approach loses some of its cleanness. 'Ability' is a messy, messy word. You seem to admit this when you call Chemero's suggestion 'hand wavy'.</i><br />Actually I was calling out Proffitt and 'effort', but I agree with this entirely. It certainly seems to be the case that 'ability' is the way to go, and it really is a worry.<br /><br />But I don't accept that we can't get into it. Especially in the throwing case, which is what I'm actually interested in right now; there are no clear body scale parameters accounting for affordance judgements in this task, and as I was writing this post I realised that eye height units aren't functional in any obvious way - they aren't about performance of the task, mostly. So it's interestingly messy, and it needs a solution, because people can throw objects to targets at set distances.Andrewhttps://www.blogger.com/profile/16732977871048876430noreply@blogger.comtag:blogger.com,1999:blog-9192597712746432631.post-12491169040270812302011-06-08T04:57:40.543+01:002011-06-08T04:57:40.543+01:00Although I can't recall the specific reference...Although I can't recall the specific references, Proffit and co have done almost all the effort manipulations you can think of (hill steepness, wearing backpacks, glucose depletion etc etc)Gavin Buckinghamhttps://www.blogger.com/profile/08539613027114375642noreply@blogger.comtag:blogger.com,1999:blog-9192597712746432631.post-7890684791982955592011-06-08T03:31:20.928+01:002011-06-08T03:31:20.928+01:00Random thoughts:
"body scale is probably only...Random thoughts:<br />"body scale is probably only a proxy measure for ability to perform the action" <br />I'm increasingly suspicious of this approach. On the one hand, it is clearly true. On the other hand, I'm worried that the ecological approach loses some of its cleanness. 'Ability' is a messy, messy word. You seem to admit this when you call Chemero's suggestion 'hand wavy'.<br />----<br /><br />Effort also seems problematic. If you think people are basing perception on effort, why not manipulate effort in more obvious ways -- have them walk the same distance up hill vs. down hill, or over obstacles, or on an oiled floor, or while wearing a heavy back-pack, etc. <br /><br />---<br /><br />The cleanest stories you can tell in ecological psychology are about how the shape of the body makes certain actions possible, and organisms are attuned to information specifying the layout of the environment in terms relevant to their particular bodies. Anything more than that requires more care in talking about than we like to think.Eric Charleshttps://www.blogger.com/profile/17412168482569793996noreply@blogger.com