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Response programming hierarchy: A word of caution when parallel programming of output parameters is indicated
Human Movement North-Holland
RESEARCH
201
Science 6 (1987) 201-204
NOTE
RESPONSE PROGRAMMING HIERARCHY: A WORD OF CAUTION WHEN PARALLEL PROGRAMMING OF OUTPUT PARAMETERS IS INDICATED * Eric BUCKOLZ
and Cam O’DONNELL
The University of Western Ontario, London, Canada
Buckolz, E. and C. O’Donnell, 1987. Response a word of caution when parallel programming indicated (Research Note). Human Movement
programming hierarchy: of output parameters is Science 6, 201-204.
Larish and Frekany (1985) and to some extent Zelaznik and Hahn (1985) have claimed support for the notion of a motor programming hierarchy while concurrently proposing that these same parameters are prepared in parallel. The logical incongruity of this position and the likely reason for its appearance are considered.
Some time ago, Requin (1980) launched the notion that the programming of response parameters might have to proceed in a fixed or hierarchical order, stating, by way of an example, that it may be of little use to know the action one will have to execute if one does not also know the limb which will have to perform this action. Subsequent research using the precuing paradigm, while avoiding a possible procedural confounding present in some earlier work (see Zelaznik (1978) for details), has yielded, upon initial inspection at least, antithetical positions with respect to the existence of an output programming hierarchy (e.g., Zelaznik et al. 1982; Zelaznik and Hahn 1985; Larish and Frekany 1985). Zelaznik and Hahn (1985) have proposed that the inconsistency among the data reported to date has likely been caused by the fact that both ‘fixed’ and ‘variable’ precuing methods have been * This work was supported by a grant to the first author from the Natural Science Engineering Research Council of Canada (P019A2). Send correspondence to E. Buckolz, Thames Hall, Faculty of Physical Education, University of Western Ontario, London, Ontario, Canada N6A 3K7.
0167-9457/87/$3.50
0 1987, Elsevier Science Publishers
B.V. (North-Holland)
and The
202
E. Buckob,
C. O’Donnell / Programming
hierarchy
utilized and that only with the former method will evidence supportive of a programming hierarchy be obtained. The position adopted here is somewhat different. It holds that the apparently discordant conclusions can be reconciled quite readily on the basis that the claim of the existence of a limited programming hierarchy by Larish and Frekany (1985) is, in fact, incompatible with their own data (this same argument would hold for a similar claim made by Zelaznik and Hahn (1985)). The purpose of this note is to illustrate this assertion through a consideration of the results reported by Larish and Frekany (1985). If one can properly assume that pre and post stimulus output programming share the same characteristics, the results yielded by the precue method must establish the presence of a ‘necessary knowledge’ constraint if the notion of an output programming hierarchy is to be sustained. To do this, one must (i) simply demonstrate that the ability to preprogramme a particular parameter depends upon a concurrent knowledge of another parameter(s), and, in addition, (ii) to show that the response parameters under study are programmed in a more or less sequential fashion. In this latter regard, it is not obligatory to demonstrate strictly additive effects on RT because, for example, either partial parallel processing and/or inflation of the estimates of the processing times for single parameters due to transmission lags would produce underadditive latency changes with the precue method; however, neither of these circumstances would stand in opposition to the existence of a programming hierarchy. Obviously, the size of any observed underadditivity would be important to consider. The intent at this point is to examine the data of Larish and Frekany (1985) in light of the requirements listed above ((i) and (ii)) with a view to determining whether a conclusion in favour of a programming hierarchy is warranted. Larish and Frekany (1985) studied three movement parameters (arm = A, direction = D, and extent = E) and utilized a modified precuing procedure which avoided the confounding present in Rosenbaum’s (1980) work. The collective results of the following three comparisons among their conditions supported the constraint of ‘necessary knowledge’ and led Larish and Frekany (1985) to conclude that a limited programming hierarchy existed for motor parameters: (a) when direction (D) was not known in advance, increases in the number of precued parameters did not produce a decline in latency magnitude (i.e., RT (D) = RT (DE) = RT (ADE), where the parameter(s) identi-
E. Buckolz,
C. O’Donnell / Programming
hierarchy
203
fied within the brackets were not foretold). Knowing A and/or E, a priori, did not facilitate RT, presumably because they could not be programmed in advance when D was unknown; (b) when D only was precued, RT decreased significantly relative to the no-precue condition (i.e., RT (AE) = RT (ADE)). This latter finding, together with (a) above, indicated that one’s ability to preprogramme arm or extent was predicated upon a knowledge of direction. On the basis of these combined findings, Larish and Frekany (1985) stated that a ‘limited’ programming hierarchy existed wherein direction had to be programmed first, with arm and extent being completed in any order thereafter. Perhaps ironically, the comparisons identified in (a) above, which contributed to the conclusion that a limited programming hierarchy of response parameters existed, in fact, provide a strong basis for arguing against such a contention. As Larish and Frekany (1985) emphasized, the comparisons noted in (a) revealed that increasing the number of post-stimulus parameters which had to be programmed did not produce a concurrent, progressive elevation in RT size, thereby indicating that the programming of these output parameters was accomplished in parallel. This being the case, it follows that: (1) with stimulus processing time held constant, RT magnitude would be determined by the longest single processing time associated with the parameter(s) to be programmed, a posteriori (Hawkins 1969) (in this instance, taken individually, direction registered the longest programming time, with arm and extent being faster, yet equivalent to one another); (2) precuing parameters whose single processing times are faster (i.e., arm and extent) than that of the slowest individual latency registered (direction) should produce no RT change whether such parameters can be preprogrammed or not; (3) RT size should register a reduction relative to the no-precue condition only when the parameter(s) with the slowest (or comparably slower) individual processing time(s) is (are) precued; and, finally, (4) RT decreases as a consequence of precuing should be predictable on the basis of the individual processing time differentials among the parameters being investigated. In this case, for example, the precuing of direction alone should reduce RT, relative to the no-precue condition, by an amount equal to the latency difference between the direction and the other two parameters in terms of their single processing time. The results of Larish and Frekany (1985), some of which were outlined in (a), (b) and (c) earlier, all comply with these
204
E. Buckoiz, C. O’Donnell / Programming hierarchy
expectations. In so doing, they provide further clear support for the position that the output parameters they examined were programmed in parallel. It is obvious then that the need to demonstrate some adequate level of sequential programming, if a programming hierarchy is to be supported, was not met. It follows that the appearance of the need for ‘necessary knowledge’, in this case movement direction, was artifactual, evolving simply as a by-product of the fact that the parameters studied had unequal single programming times. In its very simplest form, one can summarize all of the foregoing by stating that it is logically incongruent to contend that certain response parameters are programmed in parallel while concurrently claiming that these same parameters must be hierarchically processed to some extent (Larish and Frekany 1985). As well, there seems to be a failure to recognize that parallel parameter programming may produce the appearance of the need for ‘necessary knowledge’ which, if taken in isolation, would tempt one to conclude, erroneously, that a programming hierarchy is indicated. In the final analysis, then, the results currently available are all compatible with the position that a programming hierarchy for motor parameters has not yet been demonstrated.
References Hawkins, H.L., 1969. Parallel processing in complex visual displays. Perception & Psychophysics 5, 56-64. Larish, D.D. and G.A. Frekany, 1985. Planning and preparing expected and unexpected movements: reexamining the relationships of arm, direction, and extent of movement. Journal of Motor Behavior 17, 168-189. Requin, J., 1980. ‘Toward a psychobiology of preparation for action’. In: G. Stelmach and J. Requin (eds.), Tutorials in motor behavior. Amsterdam: North-Holland. Rosenbaum, D., 1980. Human movement initiation: specification of arm, direction, and extent. Journal of Experimental Psychology: General 109, 444474. Zelaznik, H.N., 1978. Precuing response factors in choice reaction time: a word of caution. Journal of Motor Behavior 10, 77-79. Zelaznik, H.N. and R. Hahn, 1985. Reaction time methods in the study of motor programming: the precuing of hand, digit and duration. Journal of Motor Behavior 17, 190-218. Zelaznik, H.N., D.C. Shapiro and M.C. Carter, 1982. The specification of digit and duration during motor programming: a new method of precuing. Journal of Motor Behavior 14, 57-68.
RESEARCH
201
Science 6 (1987) 201-204
NOTE
RESPONSE PROGRAMMING HIERARCHY: A WORD OF CAUTION WHEN PARALLEL PROGRAMMING OF OUTPUT PARAMETERS IS INDICATED * Eric BUCKOLZ
and Cam O’DONNELL
The University of Western Ontario, London, Canada
Buckolz, E. and C. O’Donnell, 1987. Response a word of caution when parallel programming indicated (Research Note). Human Movement
programming hierarchy: of output parameters is Science 6, 201-204.
Larish and Frekany (1985) and to some extent Zelaznik and Hahn (1985) have claimed support for the notion of a motor programming hierarchy while concurrently proposing that these same parameters are prepared in parallel. The logical incongruity of this position and the likely reason for its appearance are considered.
Some time ago, Requin (1980) launched the notion that the programming of response parameters might have to proceed in a fixed or hierarchical order, stating, by way of an example, that it may be of little use to know the action one will have to execute if one does not also know the limb which will have to perform this action. Subsequent research using the precuing paradigm, while avoiding a possible procedural confounding present in some earlier work (see Zelaznik (1978) for details), has yielded, upon initial inspection at least, antithetical positions with respect to the existence of an output programming hierarchy (e.g., Zelaznik et al. 1982; Zelaznik and Hahn 1985; Larish and Frekany 1985). Zelaznik and Hahn (1985) have proposed that the inconsistency among the data reported to date has likely been caused by the fact that both ‘fixed’ and ‘variable’ precuing methods have been * This work was supported by a grant to the first author from the Natural Science Engineering Research Council of Canada (P019A2). Send correspondence to E. Buckolz, Thames Hall, Faculty of Physical Education, University of Western Ontario, London, Ontario, Canada N6A 3K7.
0167-9457/87/$3.50
0 1987, Elsevier Science Publishers
B.V. (North-Holland)
and The
202
E. Buckob,
C. O’Donnell / Programming
hierarchy
utilized and that only with the former method will evidence supportive of a programming hierarchy be obtained. The position adopted here is somewhat different. It holds that the apparently discordant conclusions can be reconciled quite readily on the basis that the claim of the existence of a limited programming hierarchy by Larish and Frekany (1985) is, in fact, incompatible with their own data (this same argument would hold for a similar claim made by Zelaznik and Hahn (1985)). The purpose of this note is to illustrate this assertion through a consideration of the results reported by Larish and Frekany (1985). If one can properly assume that pre and post stimulus output programming share the same characteristics, the results yielded by the precue method must establish the presence of a ‘necessary knowledge’ constraint if the notion of an output programming hierarchy is to be sustained. To do this, one must (i) simply demonstrate that the ability to preprogramme a particular parameter depends upon a concurrent knowledge of another parameter(s), and, in addition, (ii) to show that the response parameters under study are programmed in a more or less sequential fashion. In this latter regard, it is not obligatory to demonstrate strictly additive effects on RT because, for example, either partial parallel processing and/or inflation of the estimates of the processing times for single parameters due to transmission lags would produce underadditive latency changes with the precue method; however, neither of these circumstances would stand in opposition to the existence of a programming hierarchy. Obviously, the size of any observed underadditivity would be important to consider. The intent at this point is to examine the data of Larish and Frekany (1985) in light of the requirements listed above ((i) and (ii)) with a view to determining whether a conclusion in favour of a programming hierarchy is warranted. Larish and Frekany (1985) studied three movement parameters (arm = A, direction = D, and extent = E) and utilized a modified precuing procedure which avoided the confounding present in Rosenbaum’s (1980) work. The collective results of the following three comparisons among their conditions supported the constraint of ‘necessary knowledge’ and led Larish and Frekany (1985) to conclude that a limited programming hierarchy existed for motor parameters: (a) when direction (D) was not known in advance, increases in the number of precued parameters did not produce a decline in latency magnitude (i.e., RT (D) = RT (DE) = RT (ADE), where the parameter(s) identi-
E. Buckolz,
C. O’Donnell / Programming
hierarchy
203
fied within the brackets were not foretold). Knowing A and/or E, a priori, did not facilitate RT, presumably because they could not be programmed in advance when D was unknown; (b) when D only was precued, RT decreased significantly relative to the no-precue condition (i.e., RT (AE) = RT (ADE)). This latter finding, together with (a) above, indicated that one’s ability to preprogramme arm or extent was predicated upon a knowledge of direction. On the basis of these combined findings, Larish and Frekany (1985) stated that a ‘limited’ programming hierarchy existed wherein direction had to be programmed first, with arm and extent being completed in any order thereafter. Perhaps ironically, the comparisons identified in (a) above, which contributed to the conclusion that a limited programming hierarchy of response parameters existed, in fact, provide a strong basis for arguing against such a contention. As Larish and Frekany (1985) emphasized, the comparisons noted in (a) revealed that increasing the number of post-stimulus parameters which had to be programmed did not produce a concurrent, progressive elevation in RT size, thereby indicating that the programming of these output parameters was accomplished in parallel. This being the case, it follows that: (1) with stimulus processing time held constant, RT magnitude would be determined by the longest single processing time associated with the parameter(s) to be programmed, a posteriori (Hawkins 1969) (in this instance, taken individually, direction registered the longest programming time, with arm and extent being faster, yet equivalent to one another); (2) precuing parameters whose single processing times are faster (i.e., arm and extent) than that of the slowest individual latency registered (direction) should produce no RT change whether such parameters can be preprogrammed or not; (3) RT size should register a reduction relative to the no-precue condition only when the parameter(s) with the slowest (or comparably slower) individual processing time(s) is (are) precued; and, finally, (4) RT decreases as a consequence of precuing should be predictable on the basis of the individual processing time differentials among the parameters being investigated. In this case, for example, the precuing of direction alone should reduce RT, relative to the no-precue condition, by an amount equal to the latency difference between the direction and the other two parameters in terms of their single processing time. The results of Larish and Frekany (1985), some of which were outlined in (a), (b) and (c) earlier, all comply with these
204
E. Buckoiz, C. O’Donnell / Programming hierarchy
expectations. In so doing, they provide further clear support for the position that the output parameters they examined were programmed in parallel. It is obvious then that the need to demonstrate some adequate level of sequential programming, if a programming hierarchy is to be supported, was not met. It follows that the appearance of the need for ‘necessary knowledge’, in this case movement direction, was artifactual, evolving simply as a by-product of the fact that the parameters studied had unequal single programming times. In its very simplest form, one can summarize all of the foregoing by stating that it is logically incongruent to contend that certain response parameters are programmed in parallel while concurrently claiming that these same parameters must be hierarchically processed to some extent (Larish and Frekany 1985). As well, there seems to be a failure to recognize that parallel parameter programming may produce the appearance of the need for ‘necessary knowledge’ which, if taken in isolation, would tempt one to conclude, erroneously, that a programming hierarchy is indicated. In the final analysis, then, the results currently available are all compatible with the position that a programming hierarchy for motor parameters has not yet been demonstrated.
References Hawkins, H.L., 1969. Parallel processing in complex visual displays. Perception & Psychophysics 5, 56-64. Larish, D.D. and G.A. Frekany, 1985. Planning and preparing expected and unexpected movements: reexamining the relationships of arm, direction, and extent of movement. Journal of Motor Behavior 17, 168-189. Requin, J., 1980. ‘Toward a psychobiology of preparation for action’. In: G. Stelmach and J. Requin (eds.), Tutorials in motor behavior. Amsterdam: North-Holland. Rosenbaum, D., 1980. Human movement initiation: specification of arm, direction, and extent. Journal of Experimental Psychology: General 109, 444474. Zelaznik, H.N., 1978. Precuing response factors in choice reaction time: a word of caution. Journal of Motor Behavior 10, 77-79. Zelaznik, H.N. and R. Hahn, 1985. Reaction time methods in the study of motor programming: the precuing of hand, digit and duration. Journal of Motor Behavior 17, 190-218. Zelaznik, H.N., D.C. Shapiro and M.C. Carter, 1982. The specification of digit and duration during motor programming: a new method of precuing. Journal of Motor Behavior 14, 57-68.