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Concurrent Schedules: Effects of Blackout during the Changeover Delay
Jkhallioll1l1i Proroses. 18 (1m) 87·97
87
ElsClli
Harrie Boelen. 1 , Pietar F.K. Kop2 and J .L. Slangen3 1x,eiden University, Hooigracht 15, 2312 i\1I LIOiden 2srabont Uni,"Orsity, HogeschooUaan 225, 5000 LB !l'Uburg 3university of Utrecht, Sorbonoelaan 16, JS84 CA Utrecht, The Netherlands ( lu:eepted 17 Novomber 1988 )
ABSTRACT
Boeleos, H., Kop, P.I'.H. and' Slangen, J.L., 1988 •. Cor,=ent 8chedul~.. Effect. of bl ..cI
Sahav .
FO'1lX' homIng pigeons were exposed to concur~ent variable-interval 40-a variable-intorval 120-8 schedules of rein£orcOlUont " lth
~::~~:~::; ~~t:~: ~: ~~~z::~a~~~:1~~~ ~t!' ~:~B::~O: !It.. ::
wl tbout blackout of the experimental cllamb$r .1n dlfferent , condition.. Blackout eliminated or strongly reduced responding during the changeover delay.. It clecroased ~he run length of responding after th. cbangaovar ~lay in the variable-interval 120-s oomponent, bUt it had 110 IIl'lItematlC efiect. on the run length after the changeover delay in the v~riable-interval 40-. component . III both componente, the run length. after the changeover delay increased .with the duration of che delay. Blackout increased deviationo frail reoponee matching, cODputed from meaeureo of reoponding after the changeovor delay. Tbe doviatl.onD incre/Uled with th. "uration of the chang60ver delay. The re"ulto suggest ~.h.t the finding of ovetm.atch1ng with proced\1reg other thon the changeover dolay does not depend eKcluslvely on the absence of renpon<11nq in the interval that "lapses between initiation of tbe change to an alternaUve and ths first reaponoe eligible 'for reinforcement. , Key wordsa concurrent schedules, blackout, cllangeover delay, key peck, pigeon INTRODUCTION
Concurrent VI VI schedules 8pecif~· that two v4d. able~intezv81 (VI) achodules ol'&rate .imultanooUDly for different roaponse alternatives. '!'he diotrl.butJ.on of responding in thh situation ia adequately deocribed by the equation (1)
0376-6317/891$0).50 @ 1989 Ebevl" ScI,nce PIIbti.ben 8.V. (8lomedi"l1 Division)
88
where BJ.,2 represent the number,s of responses or the timua apeR't respond!n~ on alternatives 1 and 2, and RJ,2 "Nprssent trOll ntmbers of reinforcers provided by alternativo8 1 and 2 (84U11, 19n1 Taylor and Oavi.on, 1983). The parMeter. ~ and b ~re dete:rmined by fittl.nw Equation 1 to value. of the Band R variables. The parameter a 1. a ...".ure of th.e .e.aiti'-ity of the dietribution of reepondinw to a discrepancy between tbe nwnber. of relnforcer~ providod by the two alternatives . The CtlBeS "a<1 . 0, a=1.0, and ..>1.0 aro referred to 8.8 undennatch.J.ng, matching, and ovorm~tchLng, respectively. The parGneter b indicates a biao towar.au (lltGrnati\TG 1 when b>l.O and a bias toward, alternllU.ve 2 whe .. b<1.0. It has been found tbat the parueter a veri68 with procedurel variable.. PUakoff, Cicerone and NehOR (1978) and Pli.l,of! and Fettellnan (1981) vuied a fix.d-ratio requi.ement for chang.overs b.tween respon •• alternative.. Thoy obtained undematching with .moll and ovem.tching with larqe r.qui ..lII.nt.. Dunn (1992) varied the reinforcement m.gnitud •• provided by two alt~rnative. and obtained ove""'teh1ng with a large changeover requil'Or.J
89
Van Hoaren, 1981} . On the other hend, the other. procedu:te8 prevent responding in t~e interval t~at Glopses between in1 thUon of the change to' an alternative and the first reaponae eligible for reinforcemont. It is possible that the COD ond ot~er procedures lead to the same distribution of respondl.nC) in t~e time thst response. may be reinforced. If this 'is true and equal rate. of reopondlng occur during CODa in difforent schedul.e components, then "ubeti tution ,o f th~ COD by .nother procedure lIould l.ad to the elimination of equl.Il numbers of responso8 from t.ho totitlS on the aifferent alternative.. Thie produces a more extreme distribution of responding, IIhich leads to overmatching in the l'el'Jponso moasures. Thiu expl(1nat~on dot's not aCQount for tho dl.fferential effects on the time meaeureo, and it do.s not specify y'ho variables that control responding dnring CODe. However, it provides a general statement cor.cerning tho effoct. of different . procedures for eeparatIng schedule compoMnts that nssds to be verified, becaus .. it I
90
blackout of the experimental ohmer. METHOD
Sobj_oc.. Four homing pigeons, between three and five year. old, war" maintained at Be, of thou free-f""ding .. eight_ with s\lpplell'LElntal fee-dings .?lftGr each experimental session.. '!'hay had prior al(per~ence in r.onc:urrent schedules of food reinforcement.
Jlpparatuu.
Two otandard Lehigh Valley three-Jeey pigeon teoting chambers were used. The chambers were 36 em high, 31 em long, and 35 011 wide. only the left and the middle keys '""reoparative dudng this exped!lent. Both key. were 2. 5 em in diameter and required " force of approximately .15 N to be operated. The keys were spaced a. 3 em aport (centre to <:entre). The left key could ba illuminated by a white key light, and the middle key by either a red. or a green key liqht. A houee11ght, located above the middle key, provided general l11unination. Acce.o to otandard mixed pigeon gra1.n wa. provIded through " S-cm by 6-em aperture, centred on the BartLe wall, 11 em from the floor of the chamber. A fan provided freoh air .nd some maoking noise. A PDPB/E minicomputer (Digital Bquipment COrporation), located in an adjacent roOr:L 1 and SKED software (Snapper, Stephens, _and LeB,
1974} were used to control the oxperimental procoo'Jres and da.tll collection.
procedure. Subject. 13 and 35 had their experimental .e.oion. in one chamber, Subjects 14 and 36 in the other. Each subject was exposed to a BBguence of twal va condi tiona. A ch8ng~ver kay procedure for two-alternative concurrent scheduling (Findley, 1950) was used in each condition. Pecka on the left l white key (changeover key) changed the colour of the niddle key (main ka:n. Eacl) of two independent VI schedules was associated with a different colour of the main key. When the main key was groen, i;~:::!~.r.; on the key wel:e ~lnfo.Iced on a VI 40-6 schedule, and when it. was red, pecks an d,e; l;6Y .... ete reinforced on a VI 120-s schedule. A COD, timed from each peck 011 the changeover key, was 1n effect~ Pecks on the main key that occurred 'Within a specified interval after each peck on the oho.ng-eover key could not be reinforced. The VI schedules each conBisted of 15 intervals const.ructed using the method of rleahler and Hoffman (1962).
91
Dodng preaentation of. reinforcor (3 a preaontation of grain) bc.t li achedoloa halted, the feeder waa illWDI.noted by white light, and th" rest of the chumb.... vaa darkoned. In 80"& conditions the chamber was darkened d~J:ing each COD interval · (blackout). !rh"s" conditions WGr. identier.l to the other cOndition. in all othor re8pects (changeover key pecks ware otill effect!"" and oched"le • .contLnued to oporate). !!'he d"rations of the CODe were 0, 2, B, 4, 1,. 0, 2, 8, 4, 1, 1, and 1 8 in success1ve cond1tlolUJ. (Illi tially, a eecond purpose of the pr9 ••nt e>
92
that altE.'rJlOtlve). The xee~nse rates woro roughly equal in tho This was true · for both blackout and no-btacJtout conditions. 'lbe blackout eliminated or .trongly xeduced reopond.tng during COOs.' The 'r esponse rates were essentially zero ' in the blackout condition. for all oubjects .except Subject n. 'l'his aubject responded in blackout. of all durationa
TABLE 1
Response rates (responses/min) during CODs
COD ren-p-on-.-e-r-at-e-,-S""'ub""'j-ec-t--COD dur'(;t on
14
13
36
3S
"'"4oGi2O
40
120
40
120
40
120
NB
180
164
99
o
127 0
121
103
189
226 0
NB
177
69
184 76
154 1
147 0
153
o
107 0
166
159
NB B
168
151
139
183 0
168
o
158 0
132
159
NB ·8
155
155 1
131
108 0
168
116
86
128
Bl!~but B
B
27
3
o
3S
7
o
o
o
o
0
0
o
1
o
o
2
1
0
040 • VI 40-s: 120 = VI 120-s: (N)B' (No) Blackout Figure 1 shows the lengths of maln key response runs after the COO had expired. TheBe me.suxes were· obtained by dividing tile nwnber of responses 1n a component after the COD, by the nwnber of chanqeover key pecks in the compon!)nt ofter the COO. Run lengths increased with increasing COD duration. Th1.s effect was observed for both the VI 40-8 and the VI 120-s component, 9.nd for blackout as well as nO-blackout procedures. Blackout. reduced the run . length in the VI 120-8 corrponent . Analysis of variance revealed 4 statietically siqnificant effect of COO duration on the logarithm of the run length in tile VI 40-. component, F(3,9) " 56 . 36, p< . OOl. There was no evidence for an effect of (the presence/absence of) blackout or an interacti.on of COD duration and blackout (p> . 10) . The l"9arithm of the run length in the VI 120-s component showed significant effects of COO duration, F(3,9)=16.70, p<.OOl, and blackout, F(1,3)=10 . 31, p< . OS, but there was no evidence for an
93
interaction of COD duration and blackout ~p>.lO). Logarithmic transfornations were applied beC1luse it wae. a:£rsumecl that the
standard devlat.t.on of a rll1'J. length is proportiO'.:.al to its mean (Kirk, 1982). Anal~se8 01 the un-transformed data revealed significant main effGcts of COD duration and blackout on the r-..m length in the VI 120";'8 component (p<.05), but no other effects • •••• kAl:KOIJT.YJ4(1·S .... ,. eu.tlWl." Utl-S 0--0 lIOaJ.CkOUT.
B ,0>
g §
" III
n.o-s
"jl"l"I//"/ f / j-/ :
a--o 110
'000 '01
~u.clOUT.
VI 12O·S
a/
r~~:C"
.
~"'"""
. . ..
)1""
.~. .I I
"
"
COODUMUOII (S]
"
.
Figure 1. Run lengths of responding aftar the COD as a function of COD dura't ion. Run lengths were computed by dividing the nwnber of responses in a component after tbe COD, by the number of changeover key pecka in the component after the COD. No1;a
logarithmic vertical axis.
Figure 2 shows deviations from response matching. The deviations were calculated acc[,1i:ding to the formula log(Bl/82)-log(Rl/R2l, where the subscripts 1,2 .t.n~ for the VI 40-8 and the VI 120-s components, B for number of responses, and R for number of reinforcers. This expression is negative ~'hen tho proportion of responses in the VI 40-8 component is smaller than the proportion of reinforcers, ecr.1al to zero when matching of' the proportions occurs, and positive when the response proportion is' greater. The difference between logarithms of ratios was preferred to the difference between proportIons as a
measure of deviation from matching, because· the difference between proportions lTIust ,~aniBb &8 preference becomes extreme. The squares s~ow the deviations based on numbers of responses after
the COO. • ••••
I."
II
I ! ~
S
;
f
.I
t;;
fI'
,.
."
:l'
t
y
..
,:'
" Figure 2. duration.
"
II
~
i ,...
(Ut~
..·4 ELAtlCIIT. toO OQ.. O--OllOlWlDIT o--a 10 BLAUOUt, tee oa..
...
.
II • CGOo..'UUOIIISI
Deviations from reaponse matching 88 a funotion of COO The deviations are differenco. between logged ratio. of
response frequencies and l099ed ratios of reLnforcement frequencies . Numerators of the ratios aro the measures obtained
in the VI 40-a ' component .
.
The deviations frolll response raatching br..aed on all responses were positive for all durations of the COD with b"l ackout . They were negative when the blackout was not in effect . Tbe deviations from matching obtained with the blackout procedure, after eKclusion of responses during the COO, were identical to those based on all responses except for Subject 13 and the COOs of 1, 2, and 4 s. Of course, this follows from the fact that responding during blackouts occurred only in these cases , The deviations froIl response m~tching based on post-COD responses were q~ter in blackout than in no-blaCkout conditions. An analysis of variance applied to the deviations froll post-COD response natching revealed significant effects of COD duration, F(J,9)=5 . 32, p<.05, and
95
blackout, P(l,3)'2L~8, p<.OS, but no ev.tdence for an interaction of COD duration and blackout (p>.10). Durationa of Dtay in 'a component were determined by dividing the time .ponr. in c component after the COD, by the number of changeover key packs in the component ~fter tho COD. D~:tationB of stay increased 8~ a function of COD duration. 'Ibis wt:e true for both the VI 40-. and the VI 120-a component and for b ' )~ll blackout and no-blackout conditiona. The logarithm. of the atay durations showed neither a significant effoct of blackout, nor a significant interaction of blackout Bnd COD duration (p> . 10) , Deviations from time matching were calculated in the same \113)' as deviations from responoe matching . No significant effects of. COD duration, blackout, or their interaction wore apparont (p>. 05) , Thio was found both when timo .pont in COOs wac counted and when 1t wae not counted. DISCUSSION Blackout during the COD reduced tho moan number of poat-COD per stay in the VI 120-0 component, and it lncreasod deviations from post-COD response matching. These effecta can bo interpreted in differ.ont ways. One possibility is that blackout increSBed thebiaB (b in Equation 1) for the VI 40-B alternative. Another possibility is that it incroased a, the under/overmatching: paramet.sr . In ei thet' case, however, the results show .t~Qt blackout during · the COD affect. the distr1bution of respond1ng after the COD. Therefore, the result8 suqgest that tho difference between the effect of the COD and the effects of the other procedures for separating schedule components is not based only on the occurrence of responding during the COD. Another ac~onnt of the differential effects, which 1s consistent with· i.:~e present data, refers to .punlsJunent of changeo"V"ers (Elawn, 1982; Farloy, 1980). Punlahinq each changeover in two-alternative concurrent schedules produces ilpproximately equal amounts of total punishment for both l:e~ponses, because the nurnberD of changoovors can novor differ by more than one. If the total effective reinforcemont provided by an alternative equals total reinforcement minus total punislunent then the proportions of effective reinforcement will be at least as extreme as the reinforcemont proportions and may approximate e"treme behaviour proportions. reBponse~
96
Tho response rates during COOs were approximately equal for the two a1 ternati vas in both the blackout and no .. blackout conditions of the present experiment. IJIhis l'esult fails to replicate" J'1nding of Sil~&rberg and Pantino (lHD). illey found that COD Nsponse rates on the alternative with the lower reinforcement rate were greater than those on the other al ternative in the no-blackout conditiClns. Othex: failures to obtain this finding wera reported by Manlove (1975) r\nd Van Haaren (19Bl). A procedural variable tnat may be related to this discrepancy 1s the overall reinforcement rate . Sllberberg and Fantino scheduled 40 reinforce:o::s per hour I \{hich was lower l'han the rates scheduled in the other experiments. In conclusion, the r.esults of the present study ahow that blackout during the COD affects the distribution of responding in concurrent schedules after the COD. The results can be explained by referring to punishment of changeovers bet'1een response alternatives. RBl'ERBNCES
Bawn, W.N., 1979. Matching, undermatchlng, and ovematchinq in
8 tudii.:!~ of choice. J~ expo Analysis BehBY., 321 269-281. Baum, W1M., 1982 Cho.i."oe, changeover, and travel. J. exp. Analysis Behavo., 38: 35-49. I
Boelens, If. and Kap, P . P .M. , 1983. Concurreilt 8ched.ulElfj~ Spatial separation of response alternntives oJ. expo AnAlysls Sehav., 40: 35-45. de Villiers I P. I 1977. Choice in concurrent schedules lmd a quantitative fonnulation of the law of effect . In W. K. Honig and J.E.R. Staddon (Editors), Handbook of Operant BI~haviot'. Prentice-Hall, Englewood Cliffs, N.J., pp. 233-287. Dunn, R.M., 1982. Choice, relative reinforcer duration, and the changeover .rat:i.o. J. expo Analysis aehav., 38: 313-319. Farley I J., 1980. Reinforcement and punishment effects in concurrent schedules I A test of two models. J. exp. Analysis Behav .• 33, 311-326. Findley, J.D., 1958. Preference and switching under concurrent scheduling. J. expo Analysis Behav., 1z 123-144. FleshIer, M. and Hoffman, H.S., 1962. A progression for generating variable-interval schedules, J. expo Analysis Eehav., 51 529-530.
Herrnstein, R.J., 1961 . Relative and absolute strength of response as a function of frequency of reinforcement. J. expo Analysis .Behav., 4: 267-212.
Kirk, [t.E., 1.982. Bxpartmental Design; P:r:ocedures for the Behavioral Sciences. Brooks/Cole, Monterey, 911 pp. Menlove, R.L., 1975, Local patterns of responding in multiple and concurrent schedules. J. expo Analysis Seha ...·., 13: 309-337. Pliskoff, 5.5., Cicerone, R. and Nelson, T. O. , 1978. Local response-rate constancy on concurrent variable-interval schedules of reinforcement. J ° expo Analysis Behav., 29:
97
431-446. PUBkoff, S.S. and Fetteman, J.G., 1981. onder1Oatching and overmatching J '1ho fiJced-ratio changeover requirement . J. exp. Analysis Dehav., 36. 21-27. Silborberg, A. and Fantino, E. 1970 . Cllolce, rate of reinforcement, and the cbangeover delay. J . expo Ant\lyaia Dehov . , 13. 187-197. . Snapper, A.G ., Stephens, X.ft. and L.e, O.K. , 1974 . The SilEO Software System. State Systems, Kalamazoo. Ta~'l(ir, R. and Davison, K., 1983. Sensitivity to reinforc:ement in concurrent arl thJ1tetlc and exponential ac.:hedules . J. exp. Analysis aehov., 39. 191-198 . Van Heare n, P., 1981. The effects of changeover delays of f ixed or variable dUration on conCUrl'Gnt variablo-1ntervel performance in pigeons . Anim. Learn . Be.hav ., 9, 425-431. Weaxden, J.H., and Burgess, 1.5., 1982 . Motchinq since Bawn (1979) . J. expo Analysis Boh.v . , 38. 339-348. it Thls research was carried out at Brabant University. We thank Jan Theeuwos for assistance in data collection and analyeie. Address correspondence to Harrie Boelens, Department of P8ycholo~, Leiden University, Hooigracht 15, 2312 KlI Loiden, The Netherland • •
87
ElsClli
Harrie Boelen. 1 , Pietar F.K. Kop2 and J .L. Slangen3 1x,eiden University, Hooigracht 15, 2312 i\1I LIOiden 2srabont Uni,"Orsity, HogeschooUaan 225, 5000 LB !l'Uburg 3university of Utrecht, Sorbonoelaan 16, JS84 CA Utrecht, The Netherlands ( lu:eepted 17 Novomber 1988 )
ABSTRACT
Boeleos, H., Kop, P.I'.H. and' Slangen, J.L., 1988 •. Cor,=ent 8chedul~.. Effect. of bl ..cI
Sahav .
FO'1lX' homIng pigeons were exposed to concur~ent variable-interval 40-a variable-intorval 120-8 schedules of rein£orcOlUont " lth
~::~~:~::; ~~t:~: ~: ~~~z::~a~~~:1~~~ ~t!' ~:~B::~O: !It.. ::
wl tbout blackout of the experimental cllamb$r .1n dlfferent , condition.. Blackout eliminated or strongly reduced responding during the changeover delay.. It clecroased ~he run length of responding after th. cbangaovar ~lay in the variable-interval 120-s oomponent, bUt it had 110 IIl'lItematlC efiect. on the run length after the changeover delay in the v~riable-interval 40-. component . III both componente, the run length. after the changeover delay increased .with the duration of che delay. Blackout increased deviationo frail reoponee matching, cODputed from meaeureo of reoponding after the changeovor delay. Tbe doviatl.onD incre/Uled with th. "uration of the chang60ver delay. The re"ulto suggest ~.h.t the finding of ovetm.atch1ng with proced\1reg other thon the changeover dolay does not depend eKcluslvely on the absence of renpon<11nq in the interval that "lapses between initiation of tbe change to an alternaUve and ths first reaponoe eligible 'for reinforcement. , Key wordsa concurrent schedules, blackout, cllangeover delay, key peck, pigeon INTRODUCTION
Concurrent VI VI schedules 8pecif~· that two v4d. able~intezv81 (VI) achodules ol'&rate .imultanooUDly for different roaponse alternatives. '!'he diotrl.butJ.on of responding in thh situation ia adequately deocribed by the equation (1)
0376-6317/891$0).50 @ 1989 Ebevl" ScI,nce PIIbti.ben 8.V. (8lomedi"l1 Division)
88
where BJ.,2 represent the number,s of responses or the timua apeR't respond!n~ on alternatives 1 and 2, and RJ,2 "Nprssent trOll ntmbers of reinforcers provided by alternativo8 1 and 2 (84U11, 19n1 Taylor and Oavi.on, 1983). The parMeter. ~ and b ~re dete:rmined by fittl.nw Equation 1 to value. of the Band R variables. The parameter a 1. a ...".ure of th.e .e.aiti'-ity of the dietribution of reepondinw to a discrepancy between tbe nwnber. of relnforcer~ providod by the two alternatives . The CtlBeS "a<1 . 0, a=1.0, and ..>1.0 aro referred to 8.8 undennatch.J.ng, matching, and ovorm~tchLng, respectively. The parGneter b indicates a biao towar.au (lltGrnati\TG 1 when b>l.O and a bias toward, alternllU.ve 2 whe .. b<1.0. It has been found tbat the parueter a veri68 with procedurel variable.. PUakoff, Cicerone and NehOR (1978) and Pli.l,of! and Fettellnan (1981) vuied a fix.d-ratio requi.ement for chang.overs b.tween respon •• alternative.. Thoy obtained undematching with .moll and ovem.tching with larqe r.qui ..lII.nt.. Dunn (1992) varied the reinforcement m.gnitud •• provided by two alt~rnative. and obtained ove""'teh1ng with a large changeover requil'Or.J
89
Van Hoaren, 1981} . On the other hend, the other. procedu:te8 prevent responding in t~e interval t~at Glopses between in1 thUon of the change to' an alternative and the first reaponae eligible for reinforcemont. It is possible that the COD ond ot~er procedures lead to the same distribution of respondl.nC) in t~e time thst response. may be reinforced. If this 'is true and equal rate. of reopondlng occur during CODa in difforent schedul.e components, then "ubeti tution ,o f th~ COD by .nother procedure lIould l.ad to the elimination of equl.Il numbers of responso8 from t.ho totitlS on the aifferent alternative.. Thie produces a more extreme distribution of responding, IIhich leads to overmatching in the l'el'Jponso moasures. Thiu expl(1nat~on dot's not aCQount for tho dl.fferential effects on the time meaeureo, and it do.s not specify y'ho variables that control responding dnring CODe. However, it provides a general statement cor.cerning tho effoct. of different . procedures for eeparatIng schedule compoMnts that nssds to be verified, becaus .. it I
90
blackout of the experimental ohmer. METHOD
Sobj_oc.. Four homing pigeons, between three and five year. old, war" maintained at Be, of thou free-f""ding .. eight_ with s\lpplell'LElntal fee-dings .?lftGr each experimental session.. '!'hay had prior al(per~ence in r.onc:urrent schedules of food reinforcement.
Jlpparatuu.
Two otandard Lehigh Valley three-Jeey pigeon teoting chambers were used. The chambers were 36 em high, 31 em long, and 35 011 wide. only the left and the middle keys '""reoparative dudng this exped!lent. Both key. were 2. 5 em in diameter and required " force of approximately .15 N to be operated. The keys were spaced a. 3 em aport (centre to <:entre). The left key could ba illuminated by a white key light, and the middle key by either a red. or a green key liqht. A houee11ght, located above the middle key, provided general l11unination. Acce.o to otandard mixed pigeon gra1.n wa. provIded through " S-cm by 6-em aperture, centred on the BartLe wall, 11 em from the floor of the chamber. A fan provided freoh air .nd some maoking noise. A PDPB/E minicomputer (Digital Bquipment COrporation), located in an adjacent roOr:L 1 and SKED software (Snapper, Stephens, _and LeB,
1974} were used to control the oxperimental procoo'Jres and da.tll collection.
procedure. Subject. 13 and 35 had their experimental .e.oion. in one chamber, Subjects 14 and 36 in the other. Each subject was exposed to a BBguence of twal va condi tiona. A ch8ng~ver kay procedure for two-alternative concurrent scheduling (Findley, 1950) was used in each condition. Pecka on the left l white key (changeover key) changed the colour of the niddle key (main ka:n. Eacl) of two independent VI schedules was associated with a different colour of the main key. When the main key was groen, i;~:::!~.r.; on the key wel:e ~lnfo.Iced on a VI 40-6 schedule, and when it. was red, pecks an d,e; l;6Y .... ete reinforced on a VI 120-s schedule. A COD, timed from each peck 011 the changeover key, was 1n effect~ Pecks on the main key that occurred 'Within a specified interval after each peck on the oho.ng-eover key could not be reinforced. The VI schedules each conBisted of 15 intervals const.ructed using the method of rleahler and Hoffman (1962).
91
Dodng preaentation of. reinforcor (3 a preaontation of grain) bc.t li achedoloa halted, the feeder waa illWDI.noted by white light, and th" rest of the chumb.... vaa darkoned. In 80"& conditions the chamber was darkened d~J:ing each COD interval · (blackout). !rh"s" conditions WGr. identier.l to the other cOndition. in all othor re8pects (changeover key pecks ware otill effect!"" and oched"le • .contLnued to oporate). !!'he d"rations of the CODe were 0, 2, B, 4, 1,. 0, 2, 8, 4, 1, 1, and 1 8 in success1ve cond1tlolUJ. (Illi tially, a eecond purpose of the pr9 ••nt e>
92
that altE.'rJlOtlve). The xee~nse rates woro roughly equal in tho This was true · for both blackout and no-btacJtout conditions. 'lbe blackout eliminated or .trongly xeduced reopond.tng during COOs.' The 'r esponse rates were essentially zero ' in the blackout condition. for all oubjects .except Subject n. 'l'his aubject responded in blackout. of all durationa
TABLE 1
Response rates (responses/min) during CODs
COD ren-p-on-.-e-r-at-e-,-S""'ub""'j-ec-t--COD dur'(;t on
14
13
36
3S
"'"4oGi2O
40
120
40
120
40
120
NB
180
164
99
o
127 0
121
103
189
226 0
NB
177
69
184 76
154 1
147 0
153
o
107 0
166
159
NB B
168
151
139
183 0
168
o
158 0
132
159
NB ·8
155
155 1
131
108 0
168
116
86
128
Bl!~but B
B
27
3
o
3S
7
o
o
o
o
0
0
o
1
o
o
2
1
0
040 • VI 40-s: 120 = VI 120-s: (N)B' (No) Blackout Figure 1 shows the lengths of maln key response runs after the COO had expired. TheBe me.suxes were· obtained by dividing tile nwnber of responses 1n a component after the COD, by the nwnber of chanqeover key pecks in the compon!)nt ofter the COO. Run lengths increased with increasing COD duration. Th1.s effect was observed for both the VI 40-8 and the VI 120-s component, 9.nd for blackout as well as nO-blackout procedures. Blackout. reduced the run . length in the VI 120-8 corrponent . Analysis of variance revealed 4 statietically siqnificant effect of COO duration on the logarithm of the run length in tile VI 40-. component, F(3,9) " 56 . 36, p< . OOl. There was no evidence for an effect of (the presence/absence of) blackout or an interacti.on of COD duration and blackout (p> . 10) . The l"9arithm of the run length in the VI 120-s component showed significant effects of COO duration, F(3,9)=16.70, p<.OOl, and blackout, F(1,3)=10 . 31, p< . OS, but there was no evidence for an
93
interaction of COD duration and blackout ~p>.lO). Logarithmic transfornations were applied beC1luse it wae. a:£rsumecl that the
standard devlat.t.on of a rll1'J. length is proportiO'.:.al to its mean (Kirk, 1982). Anal~se8 01 the un-transformed data revealed significant main effGcts of COD duration and blackout on the r-..m length in the VI 120";'8 component (p<.05), but no other effects • •••• kAl:KOIJT.YJ4(1·S .... ,. eu.tlWl." Utl-S 0--0 lIOaJ.CkOUT.
B ,0>
g §
" III
n.o-s
"jl"l"I//"/ f / j-/ :
a--o 110
'000 '01
~u.clOUT.
VI 12O·S
a/
r~~:C"
.
~"'"""
. . ..
)1""
.~. .I I
"
"
COODUMUOII (S]
"
.
Figure 1. Run lengths of responding aftar the COD as a function of COD dura't ion. Run lengths were computed by dividing the nwnber of responses in a component after tbe COD, by the number of changeover key pecka in the component after the COD. No1;a
logarithmic vertical axis.
Figure 2 shows deviations from response matching. The deviations were calculated acc[,1i:ding to the formula log(Bl/82)-log(Rl/R2l, where the subscripts 1,2 .t.n~ for the VI 40-8 and the VI 120-s components, B for number of responses, and R for number of reinforcers. This expression is negative ~'hen tho proportion of responses in the VI 40-8 component is smaller than the proportion of reinforcers, ecr.1al to zero when matching of' the proportions occurs, and positive when the response proportion is' greater. The difference between logarithms of ratios was preferred to the difference between proportIons as a
measure of deviation from matching, because· the difference between proportions lTIust ,~aniBb &8 preference becomes extreme. The squares s~ow the deviations based on numbers of responses after
the COO. • ••••
I."
II
I ! ~
S
;
f
.I
t;;
fI'
,.
."
:l'
t
y
..
,:'
" Figure 2. duration.
"
II
~
i ,...
(Ut~
..·4 ELAtlCIIT. toO OQ.. O--OllOlWlDIT o--a 10 BLAUOUt, tee oa..
...
.
II • CGOo..'UUOIIISI
Deviations from reaponse matching 88 a funotion of COO The deviations are differenco. between logged ratio. of
response frequencies and l099ed ratios of reLnforcement frequencies . Numerators of the ratios aro the measures obtained
in the VI 40-a ' component .
.
The deviations frolll response raatching br..aed on all responses were positive for all durations of the COD with b"l ackout . They were negative when the blackout was not in effect . Tbe deviations from matching obtained with the blackout procedure, after eKclusion of responses during the COO, were identical to those based on all responses except for Subject 13 and the COOs of 1, 2, and 4 s. Of course, this follows from the fact that responding during blackouts occurred only in these cases , The deviations froIl response m~tching based on post-COD responses were q~ter in blackout than in no-blaCkout conditions. An analysis of variance applied to the deviations froll post-COD response natching revealed significant effects of COD duration, F(J,9)=5 . 32, p<.05, and
95
blackout, P(l,3)'2L~8, p<.OS, but no ev.tdence for an interaction of COD duration and blackout (p>.10). Durationa of Dtay in 'a component were determined by dividing the time .ponr. in c component after the COD, by the number of changeover key packs in the component ~fter tho COD. D~:tationB of stay increased 8~ a function of COD duration. 'Ibis wt:e true for both the VI 40-. and the VI 120-a component and for b ' )~ll blackout and no-blackout conditiona. The logarithm. of the atay durations showed neither a significant effoct of blackout, nor a significant interaction of blackout Bnd COD duration (p> . 10) , Deviations from time matching were calculated in the same \113)' as deviations from responoe matching . No significant effects of. COD duration, blackout, or their interaction wore apparont (p>. 05) , Thio was found both when timo .pont in COOs wac counted and when 1t wae not counted. DISCUSSION Blackout during the COD reduced tho moan number of poat-COD per stay in the VI 120-0 component, and it lncreasod deviations from post-COD response matching. These effecta can bo interpreted in differ.ont ways. One possibility is that blackout increSBed thebiaB (b in Equation 1) for the VI 40-B alternative. Another possibility is that it incroased a, the under/overmatching: paramet.sr . In ei thet' case, however, the results show .t~Qt blackout during · the COD affect. the distr1bution of respond1ng after the COD. Therefore, the result8 suqgest that tho difference between the effect of the COD and the effects of the other procedures for separating schedule components is not based only on the occurrence of responding during the COD. Another ac~onnt of the differential effects, which 1s consistent with· i.:~e present data, refers to .punlsJunent of changeo"V"ers (Elawn, 1982; Farloy, 1980). Punlahinq each changeover in two-alternative concurrent schedules produces ilpproximately equal amounts of total punishment for both l:e~ponses, because the nurnberD of changoovors can novor differ by more than one. If the total effective reinforcemont provided by an alternative equals total reinforcement minus total punislunent then the proportions of effective reinforcement will be at least as extreme as the reinforcemont proportions and may approximate e"treme behaviour proportions. reBponse~
96
Tho response rates during COOs were approximately equal for the two a1 ternati vas in both the blackout and no .. blackout conditions of the present experiment. IJIhis l'esult fails to replicate" J'1nding of Sil~&rberg and Pantino (lHD). illey found that COD Nsponse rates on the alternative with the lower reinforcement rate were greater than those on the other al ternative in the no-blackout conditiClns. Othex: failures to obtain this finding wera reported by Manlove (1975) r\nd Van Haaren (19Bl). A procedural variable tnat may be related to this discrepancy 1s the overall reinforcement rate . Sllberberg and Fantino scheduled 40 reinforce:o::s per hour I \{hich was lower l'han the rates scheduled in the other experiments. In conclusion, the r.esults of the present study ahow that blackout during the COD affects the distribution of responding in concurrent schedules after the COD. The results can be explained by referring to punishment of changeovers bet'1een response alternatives. RBl'ERBNCES
Bawn, W.N., 1979. Matching, undermatchlng, and ovematchinq in
8 tudii.:!~ of choice. J~ expo Analysis BehBY., 321 269-281. Baum, W1M., 1982 Cho.i."oe, changeover, and travel. J. exp. Analysis Behavo., 38: 35-49. I
Boelens, If. and Kap, P . P .M. , 1983. Concurreilt 8ched.ulElfj~ Spatial separation of response alternntives oJ. expo AnAlysls Sehav., 40: 35-45. de Villiers I P. I 1977. Choice in concurrent schedules lmd a quantitative fonnulation of the law of effect . In W. K. Honig and J.E.R. Staddon (Editors), Handbook of Operant BI~haviot'. Prentice-Hall, Englewood Cliffs, N.J., pp. 233-287. Dunn, R.M., 1982. Choice, relative reinforcer duration, and the changeover .rat:i.o. J. expo Analysis aehav., 38: 313-319. Farley I J., 1980. Reinforcement and punishment effects in concurrent schedules I A test of two models. J. exp. Analysis Behav .• 33, 311-326. Findley, J.D., 1958. Preference and switching under concurrent scheduling. J. expo Analysis Behav., 1z 123-144. FleshIer, M. and Hoffman, H.S., 1962. A progression for generating variable-interval schedules, J. expo Analysis Eehav., 51 529-530.
Herrnstein, R.J., 1961 . Relative and absolute strength of response as a function of frequency of reinforcement. J. expo Analysis .Behav., 4: 267-212.
Kirk, [t.E., 1.982. Bxpartmental Design; P:r:ocedures for the Behavioral Sciences. Brooks/Cole, Monterey, 911 pp. Menlove, R.L., 1975, Local patterns of responding in multiple and concurrent schedules. J. expo Analysis Seha ...·., 13: 309-337. Pliskoff, 5.5., Cicerone, R. and Nelson, T. O. , 1978. Local response-rate constancy on concurrent variable-interval schedules of reinforcement. J ° expo Analysis Behav., 29:
97
431-446. PUBkoff, S.S. and Fetteman, J.G., 1981. onder1Oatching and overmatching J '1ho fiJced-ratio changeover requirement . J. exp. Analysis Dehav., 36. 21-27. Silborberg, A. and Fantino, E. 1970 . Cllolce, rate of reinforcement, and the cbangeover delay. J . expo Ant\lyaia Dehov . , 13. 187-197. . Snapper, A.G ., Stephens, X.ft. and L.e, O.K. , 1974 . The SilEO Software System. State Systems, Kalamazoo. Ta~'l(ir, R. and Davison, K., 1983. Sensitivity to reinforc:ement in concurrent arl thJ1tetlc and exponential ac.:hedules . J. exp. Analysis aehov., 39. 191-198 . Van Heare n, P., 1981. The effects of changeover delays of f ixed or variable dUration on conCUrl'Gnt variablo-1ntervel performance in pigeons . Anim. Learn . Be.hav ., 9, 425-431. Weaxden, J.H., and Burgess, 1.5., 1982 . Motchinq since Bawn (1979) . J. expo Analysis Boh.v . , 38. 339-348. it Thls research was carried out at Brabant University. We thank Jan Theeuwos for assistance in data collection and analyeie. Address correspondence to Harrie Boelens, Department of P8ycholo~, Leiden University, Hooigracht 15, 2312 KlI Loiden, The Netherland • •