Fast trial pacing in a lexical decision task reveals a decay of automatic semantic activation

Acta Psychologica 133 (2010) 127–136

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Fast trial pacing in a lexical decision task reveals a decay of automatic semantic activation q James H. Neely *, Patrick A. O’Connor, Gennaro Calabrese Department of Psychology, University at Albany, State University of New York, Albany, NY 12222, United States

a r t i c l e

i n f o

Article history: Received 8 July 2009 Received in revised form 9 October 2009 Accepted 2 November 2009 Available online 4 December 2009 PsycINFO classification: 2346 Keywords: Semantic priming Trial pacing Intertrial interval Expectancy Relatedness proportion

a b s t r a c t We report an experiment showing that reducing attentional resources by presenting trials with a short, 400 ms intertrial interval (ITI) (a) did not affect semantic priming at a 160 ms prime-to-target stimulusonset asynchrony (SOA), relative to a 2500 ms ITI, and (b) eliminated the priming that occurred at a 1200 ms SOA when the ITI was 2500 ms. However, the elimination of priming at the 1200 ms SOA occurred only when the relatedness proportion (RP, proportion of related primes and targets) was .25 and not when it was .75. We interpret these results as showing that attentional/strategic priming occurs with an RP as low as .25, but only when sufficient attentional resources are available. Equally important, this is the first direct evidence that automatic semantic activation decays within 1200 ms in the standard semantic-priming/lexical-decision paradigm when attentional resources are not being used to maintain the goal of sustaining prime activation. We further argue that the frequent occurrences of related primes and targets with a high RP serve as reminders to maintain that goal such that cognitive load does not reduce long-SOA priming when the RP is high. Ó 2009 Elsevier B.V. All rights reserved.

1. Introduction ‘‘Semantic” priming is the finding that responses to a target word such as lion are faster when it is preceded by a semantically or associatively related prime (tiger) rather than an unrelated prime (ankle). This effect (see McNamara, 2005; Neely, 1991, for reviews) has often been attributed to two mechanisms: automatic spreading activation and expectancy (Neely, 1977; Posner & Snyder, 1975). Automatic spreading activation (ASA) is fast-acting, strategy-free, can occur without intention or awareness and does not require attentional resources. It produces facilitation for targets related to the prime but no inhibition for unrelated targets (Neely, 1977). Presumably, ASA decays rapidly so as to allow the cognitive system to select only recently activated (likely relevant) information for further attention-based processing and to avoid interference from less recently activated (likely irrelevant) information. Indeed, in his ACT* model, Anderson (1983) explicitly postulated an activation-damping mechanism that generates a rapid decay of ASA. The second priming mechanism, expectancy, is

q The first and second authors are at the Department of Psychology, University at Albany, State University of New York. This research fulfilled a requirement for the third author’s Honors Program in Psychology at the University at Albany. These data were presented at the May, 2006, Association for Psychological Science meetings. * Corresponding author. Tel.: +1 518 442 5013; fax: +1 518 442 4867. E-mail address: [email protected] (J.H. Neely).

0001-6918/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.actpsy.2009.11.001

slow-acting, strategic, and requires intention and attentional resources. It produces facilitation for expected (typically related) targets and inhibition for unexpected (typically unrelated) targets (Neely, 1977). Neely (1977) dissociated these two priming mechanisms in a lexical decision task in which the word or nonword target was immediately preceded by a silently read category-name prime or a string of Xs that served as a neutral prime. In some conditions, participants were induced to use the category-name prime (e.g., BODY) as a cue to generate an expectancy for word targets (e.g., ceiling, floor, and window) that were members of a pre-specified different category (‘‘BUILDING PARTS”). With a prime-to-target stimulus-onset asynchrony (SOA) of 250 ms, which presumably did not allow enough time for an expectancy to be generated from the prime, priming was inferred to be caused only by ASA that is not under strategic control. This inference was supported by the findings that relative to the XXXX neutral prime, the BODY prime produced facilitation for rarely occurring ‘‘unexpected” related targets such as stomach but neither facilitation nor inhibition for unrelated targets, including even the frequently occurring ‘‘expected” but unrelated ‘‘BUILDING PARTS” targets such as door. However, with SOAs of 700 and 2000 ms, there was evidence that priming was now being produced by expectancy because the BODY prime now yielded facilitation for ‘‘expected” but unrelated targets such as door and inhibition rather than facilitation for ‘‘unexpected” related targets such as stomach.

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Of particular relevance to the present research was the finding that inhibition was consistently less for unexpected, related targets (BODY-stomach) than for unexpected, unrelated targets (BODY-robin). Specifically at the 250, 400, 700, and 2000 ms SOAs, inhibition was, respectively, 36, 36, 17 and 24 ms less for the BODY-stomach condition than for the BODY-robin condition. This suggests that ASA persisted for at least 2000 ms, serving to reduce the inhibition caused by the target’s being unexpected. However, many researchers have cited these data as showing that ASA rapidly decays within 500–700 ms. This standard interpretation is likely based on the 17 ms difference between BODY-stomach and BODY-robin not having been statistically significant at the 700 ms SOA.1 However, the fact that inhibition was significantly reduced by 24 ms in the BODYstomach condition relative to the BODY-robin condition at the 2000 ms SOA suggests that ASA did not decay within 2000 (or 700) ms. Additional support for the absence of decay comes from the nonsignificant 17 ms reduction of inhibition in the BODY-stomach condition at the 700 ms SOA not having been statistically different from the significant 36 ms reduction at the 250 ms SOA. (In the only other lexical decision experiment that used Neely’s, 1977 category-shift instructions and included both the unexpected-related and unexpected-unrelated conditions, Burke, White, & Diaz, 1987 also failed to find evidence of decay. The priming differences in these two conditions were 41 and 37 ms at their 410 and 1550 ms SOAs.) However, the standard view that if ASA is not being sustained via attentional processing it decays within 1 s or so could still be correct. That is, participants may have had sufficient time to rehearse/activate the expectancy instructions during the 700 or 2000 ms prime–target SOAs. If so, the activation of ‘‘BODY” in the rehearsed ‘‘BODY-BUILDING” instruction could have resulted in the decaying ASA of ‘‘body parts” having been refreshed/reactivated in close temporal proximity to the target’s appearance, such that the initial decay that actually occurred would not have been observed.2 This ‘‘rehearsal” problem was potentially avoided in five studies (cited at the end of this paragraph) that used the more standard priming procedures in which participants silently read the prime and were not instructed to expect targets unrelated (or related) to the prime. In these studies, the targets unrelated to the primes were never sampled from the same, pre-specified semantic category, and the prime–target SOA was manipulated between participants, with the shortest SOA being 240 ms or shorter and the longest SOA being 1040 ms or longer. These five studies also manipulated the relatedness proportion (RP), which is the proportion of word-prime/word-target trials in which the prime and target are related. In all five studies, at SOAs of 300 ms or longer when expectancy could be operating, increases in RP led to increases in priming, the so-called RP effect. This suggests that as RP increases, participants become more motivated to use the prime to generate an expectancy for a related target, thereby increasing expectancy-

1

There is another likely reason that Neely’s (1977) results are cited as showing that ASA decays within 700 ms when it is not being sustained via attentional processing or expectancy. In his Table 1 in which he derived ordinal predictions for the various conditions in his experiment, as a simplifying assumption Neely entered a 0 for the effect of ASA at the long SOA. He made this simplying assumption that ASA would have completely decayed based in part on results reported by Loftus (1973) in a category-exemplar generation task. However, his most crucial ordinal predictions would have also held had there been no decay of ASA during the longer SOAs. Hence, the decay of ASA is not necessarily supported by the confirmation of these predictions, even though they were based on the simplifying assumption that ASA completely decays within 700 ms. 2 Although we discuss the implications that our results have for the decay of ASA along links connecting localist word nodes, we believe these implications apply with equal force to the decay of activation in distributed computational models (e.g., Masson, 1995) that assume that priming is produced by activation in distributed semantic features shared by the prime and target. It is important to note that the present experiment was not designed to differentiate between ASA and feature/ representation overlap views of automatic priming.

based priming. However, at SOAs shorter than 300 ms when expectancies would not have enough time to have been generated and priming should be produced only by fast-acting ASA, RP had no effect on priming. Because the RP effect at the longer SOAs suggests that expectancy-based priming was operating at these longer SOAs, any priming occurring at these longer SOAs could be due to expectancy rather than persisting (nondecaying) ASA. However, this ambiguity can presumably be resolved by examining long-SOA priming with an RP of .25 or lower, which is supposedly low enough to eliminate the motivation to use an expectancy strategy at the longer SOAs. In the five studies that have done this, longSOA priming with an RP of .25 or lower was always significant and statistically equivalent to short-SOA priming. Specifically, the short-SOA/long-SOA priming effects were as follows: de Groot (1984), 58/59 ms; den Heyer, Briand and Dannenbring (1983), 30/20 ms; Hutchison, Neely, & Johnson, 2001, 26/34 ms; Stolz, Besner, and Carr (2005), 28/19 ms; and Stolz and Neely (1995), 34/ 45 ms, with the overall mean for these five studies being 35/ 35 ms. This suggests that ASA did not decay within 1040 ms despite the RP always being less than .25, which presumably should have curtailed sustained attentional processing of the prime and minimized strategic expectancies.3 Two possible explanations for the seeming lack of ASA decay in these five studies are that (a) contrary to popular belief, ASA persists for at least one or two seconds when it is not supplemented by either sustained attentional processing of the prime or an expectancy and (b) these experiments did not completely eliminate either sustained attentional processing of the prime or expectancies at the long SOAs even at the low RPs, in which case ASA may indeed decay rapidly when it is not being maintained by these mechanisms, congruent with popular belief. In favor of the latter possibility is that to our knowledge no study has provided direct evidence that RPs of .25 or lower entirely eliminate sustained attentional processing of the prime or expectancies, although it has been amply demonstrated that expectancy-based priming is less for lower RPs than for higher RPs. Data suggesting that low RPs may not eliminate attention-based priming are reported by O’Connor and VanVoorhis (2004). They found that priming with a low RP of .25 was moderated by working memory capacity at a 1200 ms SOA, but not at a 300 ms SOA.4 Presumably, sustained attentional prime processing and generating an expectancy depend on working memory capacity but ASA does not. Because these two mechanisms are more likely to contribute to priming at long than short SOAs, these data suggest that even at low RPs long-SOA priming for at least some participants (i.e., those with high working memory capacity) is based on sustained attentional prime processing and/or expectancy.5 In the present experiment we sought to determine whether ASA does indeed decay within 1200 ms at a .25 RP when sustained

3 In Section 4 we discuss the results from studies that have used nonstandard priming procedures in which participants responded to both the prime and target and in which unrelated words intervened between the prime and its related target. 4 Hutchison (2007) has reported the related finding that working memory capacity is positively correlated with the RP effect for priming at a long SOA but not at a short SOA. However, for his .22 RP he failed to find that priming decreased significantly from a 267 ms SOA to a 1240 ms SOA for individuals with a low working memory capacity. However, it should be noted that he did not use the standard RP manipulation. That is, whether the target had a .22 or .78 probability of being related to the prime was cued on each trial; the overall probability of the target being related to its prime was .5 in the whole list. 5 Although we have focused on the role that the strategic mechanism expectancy might play in concealing the decay of ASA, it is also possible that another strategic mechanism, semantic matching (see Neely, 1977; Neely & Keefe, 1989; Neely, Keefe, & Ross, 1989), could be doing so as well. We consider this possibility further in Section 4. However, because semantic matching also consumes attentional resources (see Tse & Neely, 2007a, for some evidence of this), the predictions we later make for the effects of cognitive load on expectancy-based priming also hold if semantic matching is mediating priming at our long SOA for our .25 RP.

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attentional prime processing and expectancy are undermined by cognitive load. To accomplish this, we used a short intertrial interval (ITI) of 400 ms, assuming that this more rapid pacing of trials would deplete attentional resources and greatly reduce or eliminate sustained attentional prime processing and expectancies. More specifically, our design factorially crossed the variables of Prime Type (related vs. unrelated), SOA (160 ms vs. 1200 ms), RP (.25 vs. .75), and ITI (400 ms vs. 2500 ms). In line with prior studies that have typically used ITIs longer than 1500 ms (which should yield a relatively low cognitive load), we expect that with our 2500 ms ITI, priming will be (a) unaffected by RP at our 160 ms SOA but will increase as RP increases at our 1200 ms SOA and (b) significantly greater at the 1200 ms SOA than at the 160 ms SOA when the RP is 0.75. This would replicate previous results and suggest that short-SOA priming is automatic and long-SOA priming is strategically/attentionally mediated. For the .25 RP with our 2500 ms ITI, we also expect that priming will not decrease as SOA increases, replicating previous findings. Moreover, if the priming observed at our 160 ms SOA is truly automatic, then it should be affected by neither cognitive load (ITI) nor RP. The more important and novel issue is what the relative magnitudes of priming at our short and long SOAs will be with an RP of .25 with our short, 400 ms ITI, which will presumably increase cognitive load and eliminate or greatly reduce sustained attentional prime processing and expectancy. If the priming previously observed at long SOAs with a low RP and ITIs longer than 1500 ms was being mediated in part by sustained attentional processing of the prime or expectancy, the increased cognitive load produced by the 400 ms ITI should greatly reduce (or perhaps even eliminate) these sources of priming, thereby revealing whether or not ASA decays during the 1200 ms SOA. If a null priming effect now occurs at the 1200 ms SOA when there is cognitive load, it would suggest that (a) long-SOA priming with long ITIs is mediated by sustained attentional prime processing and/or expectancy even when the RP is only .25 and (b) ASA decays within 1200 ms when cognitive load reduces/eliminates sustained attentional processing of the prime and expectancy. To provide a manipulation check of whether shortening the ITI actually made it less likely that a participant would generate an expectancy or allocate attentional resources to the prime, in a post-session questionnaire we asked participants to estimate how often they ignored the prime. (They were also asked to estimate the percentage of trials that contained semantically related primes and targets.) If the short ITI did reduce attentional resources that would have been devoted to prime processing, compared to participants who received the longer ITI, participants receiving the short ITI should report having ignored the prime more frequently. 2. Method 2.1. Design The experiment employed a 2 (Prime Type: related or unrelated)  2 (RP: .25 or .75)  2 (SOA: 160 or 1200 ms)  2 (ITI: 400 or 2500 ms) mixed factorial design with ITI and RP as between-participants factors and SOA and Prime Type manipulated within the participants. SOA was blocked into separate halves of the experiment, and block order was counterbalanced across participants. Each Prime Type occurred randomly within each block for each participant. 2.2. Participants The 246 undergraduates from the University at Albany, State University of New York, who participated did so for extra credit

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or for a research requirement for an introductory psychology course. All were native speakers of English and self-reported having normal or corrected-to-normal vision. 2.3. Materials Two-hundred and eighty semantically/associatively related word pairs served as the related prime–target pairs. For 120 pairs, the target words were altered to form pronounceable nonword targets by replacing one or two interior letters. The primes for these 120 nonword targets were then randomly re-paired such that no nonword target looked like a word related to its prime. Eighty of the remaining 160 word-target pairs were critical pairs that were rotated through all conditions and their results analyzed. The 80 critical target words ranged from three to six letters in length, had a mean (with 95% confidence interval) log HAL frequency of 4.368 ± .146 and an average lexical decision RT of 595 ± 11 ms from the ELP database (Balota et al., 2002). The length of the 80 accompanying prime words ranged from three to eleven letters, and the primes had an average log HAL frequency of 3.600 ± .197 and an average lexical decision RT (from ELP) of 658 ± 16 ms. The mean forward associative strength of the critical pairs was .67 ± .03 and the mean backward associative strength of these pairs was .16 ± .05 based on the Nelson, McEvoy, and Schreiber (1998) norms. Sixteen different versions of the experiment were created by rotating each target word through each level of the two levels for Prime Type, SOA, RP, and ITI. In these 16 lists, the order in which the targets were presented was exactly the same with the Prime-Type counterbalancing being accomplished by rotating the primes. Each participant received 20 trials representing each Prime Type  SOA condition. The 80 remaining filler pairs were all unrelated in the .25 RP lists and all related in the .75 RP lists. 2.4. Procedure Once seated at a computer running E-Prime software (Schneider, Eschman, & Zuccolotto, 2002), participants were told to pay attention to the fixation symbol (+), to read the uppercase prime word silently, and to respond as quickly and accurately as possible to the following target with either a ‘‘word” or a ‘‘nonword” keypress with their left or right index fingers, respectively. Stimuli appeared centered on the monitor in white, bold, 18-point Courier New font on a black background. The fixation point appeared for 310 ms, followed by a 110 ms blank screen, yielding a 420 ms warning signal interval, which was followed by a 110 ms prime, and then a blank screen for either 50 or 1090 ms before the target appeared. The response triggered a blank screen of either 400 or 2500 ms (the ITI), creating a target response-to-prime interval of 820 or 2920 ms, respectively. Because the 420 ms warning signal interval was the same for both ITIs, any effect of ITI that occurs cannot be attributed to differences in the amount of time participants had to prepare for the next prime’s appearance following their responses to the targets. Fifteen initial warmup trials were given, with an ITI of 1450 ms, a target response-to-prime interval of 1870 ms and an SOA of 585 ms, which are the averages of the two ITIs, the two target-to-prime intervals and the two SOAs used in the experiment. After the warmup trials, participants were informed that the ITI and SOA would either get ‘‘shorter” or ‘‘longer” and were given 15 practice trials with the ITI that would be used for the rest of the session, and the SOA that would be used for the first half of that session. Another 15 practice trials with the other SOA were given before the start of the second half of each session. Each half of the experimental trials consisted of three blocks of 47, 47, and 46 trials with self-paced breaks in between. All three blocks within a half were presented with either the 160 or 1200 ms SOA. A short computerized questionnaire followed

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the lexical decision task. Participants were first asked the following: ‘‘Please estimate the percentage of trials that had two related words. Type your response using the number keys.” Then they were asked, ‘‘Did you ever find yourself ignoring the first, uppercase word? If so, how often do you think you did this?” and told to press the 1 key for ‘‘Never/Almost Never”, the 2 key for ‘‘Sometimes”, or the 3 key for ‘‘Often”. Including the brief post-task questionnaire, the session lasted 40 min. 3. Results and discussion Data were discarded from (a) 12 participants (2, 3, 1, and 6 in the .25/400 ms, .25/2500 ms, .75/400 ms and .75/2500 ms groups, respectively) who had less than 80% accuracy in any single condition or an overall mean RT greater than 3.5 standard deviations from the sample mean for their groups and (b) 10 participants who failed to follow instructions or experienced a computer crash. There were 56 participants in each of the four RP  ITI groups, with 14 participants receiving each of the four SOA  Prime-Type counterbalancing lists. For correct responses, RTs more than 3.5 standard deviations from a participant’s overall mean (2.2%) were discarded prior to analysis as were RTs for errors (2.2%). The means for the retained RTs and the mean percentage of errors made are presented in Table 1 for all cells of the experiment. Fig. 1 displays the data of central interest, which are the RT priming effects (unrelated RT minus related RT) for all cells in the experiment. Unless otherwise noted, all reported p-values are two-tailed and effects called significant were associated with p-values less than .05, two-tailed. Each reported effect is accompanied by its 95% confidence interval. In the following sections we focus on comparing those priming effects within our complex 4-factor design that are pertinent to the predictions made in Section 1. We do not discuss the error data in much detail because the error rates (see Table 1) were generally low, ranging from 1.2% to 4.7% and because there were no significant priming effects in the error data that had a sign opposite to that of the significant priming effects in RTs. Indeed, priming effects for errors were typically in the same direction as their corresponding priming effects for RTs, though the error priming effects were statistically significant less often than the RT priming effects. (The 95% confidence intervals for the individual priming effects and the RP effects for errors are given in Table 1.) Thus, there were no speed/accuracy trade-off problems. However, we do describe statistics for errors when they yield statistically significant differences that were not significant for RTs. Before turning to the planned comparisons outlined in Section 1, we note that neither RTs nor errors were affected by the ITI manip-

Fig. 1. Mean priming effects in ms for the present experiment as a function of SOA, RP, and ITI. Asterisks denote statistically significant simple effects. ‘‘CL” stands for cognitive load.

ulation (both Fs < .48). On its face, this would seem to indicate that cognitive load was not greater for the 400 ms ITI than for the 2500 ms ITI. This issue will be addressed later in Section 3.4.

3.1. Replication of prior results with the 2500 ms ITI As shown in the left half of Fig. 1, with the 2500 ms ITI which presumably yielded a relatively low cognitive overload, we replicated the standard Prime Type  RP  SOA interaction, although the three-way interaction in our three-way mixed-factor ANOVA, with Prime Type and SOA as within-participant factors and RP as a between-participant factor, did not quite reach conventional levels of statistical significance [F(1, 110) = 3.21, MSe = 934.79, p = .076]. That is, at the 1200 ms SOA, priming increased by 18.2 ± 18.5 ms as RP increased from .25 to .75 (p = .03, one-tailed), whereas at the 160 ms SOA the – 3 ± 16 ms effect of increasing RP did not approach significance (p > .75). The 21 ± 23 ms difference between the RP effects at the long and short SOAs was also significant by a one-tailed test [t(110) = 1.79 [SEdiff = 11.56], p = .038]. Also as predicted for the long ITI and .75 RP, the 47 ± 14 ms priming effect at the 1200 ms SOA was greater than the 14 ± 10 ms priming effect at the 160 ms SOA. This 33 ± 15 ms increase in priming as SOA increased was significant [t(55) = 4.34 [SEM = 7.47]. Finally, as indicated by the arrow in the left panel of Fig. 1, our long ITI data with the .25 RP also replicated prior results by failing to show a decay of ASA. That is, the 28 ± 13 ms priming effect at the 1200 ms SOA was somewhat greater, not less, than the 17 ± 13 ms priming effect at the 160 ms SOA. However, the 11 ± 18 ms difference between these two priming effects was not significant [t(55) = 1.33, SEM = 8.82, p = .19].

Table 1 Mean reaction time (RT), percent errors (PE), and simple priming effects with 95% confidence intervals as a function of stimulus-onset asynchrony (SOA), relatedness proportion (RP), and intertrial interval (ITI). SOA

Prime

2500 ms ITI

400 ms ITI

.25 RP

160 ms Priming (RT) Priming (PE) 1200 ms

Unrelated Related

Unrelated Related

Priming (RT) Priming (PE) * **

p < .05, two-tailed. p < .05, one-tailed.

.75 RP

RT

PE

RT

PE

579 562 17 ± 13* 0.9 ± 1.2 591 562 28 ± 13* 1.4 ± 1.0*

1.7 2.6

587 573 14 ± 10* 0.6 ± 1.0 615 568 47 ± 14* 2.5 ± 1.3*

2.0 1.3

2.6 1.2

.25 RP RPE

2 ± 16 1.5 ± 1.5** 4.2 1.7 18 ± 18** 1.2 ± 1.6

.75 RP

RT

PE

RT

PE

600 588 12 ± 10* 0.6 ± 0.9 594 598 4 ± 12 0.1 ± 1.6

2.2 1.7

583 567 16 ± 7* 1.4 ± 1.6** 604 562 43 ± 16* 2.0 ± 1.2*

3.1 1.7

2.5 2.4

RPE

5 ± 12 0.8 ± 1.8 3.2 1.3 47 ± 20* 1.9 ± 2.0**

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3.2. Is priming at the 160 ms SOA automatic? A three-way mixed-factor ANOVA on the RT data for the 160 ms SOA, with Prime Type as a within-participant factor and RP and ITI as between-participant factors, revealed that the only significant effect was the priming main effect [F(1, 220) = 34.72, MSe = 701.43]. All other effects were nonsignificant (all Fs < .6). Though numerically small, for the 2500 ms ITI the individual 17 ± 13 ms and the 14 ± 10 ms priming effects for the .25 and .75 RPs, respectively, were both significant, as were the corresponding 12 ± 10 ms and the 16 ± 7 ms priming effects for the 400 ms ITI. Most importantly, the fact that these priming effects were unaffected by our RP and ITI manipulations suggests that they were caused by ASA and not by attentionally mediated priming mechanisms. 3.3. Assessing the decay of ASA for the .25 RP To assess whether ASA decays with the low, .25 RP when attentional resources are reduced by cognitive load with the 400 ms ITI, we conducted a three-way mixed-factor ANOVA on the RTs for the .25 RP, with Prime Type and SOA as within-participant factors and ITI as a between-participant factor. The three-way interaction was significant [F(1, 110) = 5.34, MSe = 1014.65], confirming that the changes in priming across SOA differed for the two ITIs for the .25 RP. For the 2500 ms ITI, priming was numerically greater at the 1200 ms SOA than at the 160 ms SOA. However, this 12 ± 18 ms [t(55) = 1.33, SEM = 8.82, p = .19] difference was not significant. In contrast, as shown by the arrow in the right panel of Fig. 1, when cognitive load was presumably increased by the 400 ms ITI, there was a nearly significant 16.1 ± 16.4 ms reduction in priming at the long SOA relative to the short SOA [t(55) = 1.96, SEM = 8.20, p = .028, one-tailed], with the 12 ± 10 ms priming effect at the 160 ms SOA being significant and the 4 ± 12 ms priming effect at the 1200 ms SOA not even approaching significance. This finding suggests that if attentional resources are depleted by shortening the ITI, ASA decays within 1200 ms when the RP is .25. An analogous ANOVA on the error data also revealed a significant Prime Type  SOA  ITI interaction [F(1, 110) = 4.76, MSe = 10.57], with no other significant effects (all Fs < 2.2). With the long ITI, priming for errors increased significantly by 2.2 ± 1.6% (from a nonsignificant 0.9 ± 1.6% to a significant +1.4 ± 1.0%) as the SOA increased from 160 ms to 1200 ms [t(55) = 2.78, SEM = 0.81]; with the short ITI, priming for errors showed a numerical 0.5 ± 1.9% decrease (from a nonsignificant +0.6 ± 0.9% to a nonsignificant +0.1 ± 1.6%) as SOA increased. Because the significant 2.2% ± 1.6% increase in priming for errors from the short to the long SOA for the 2500 ms ITI converges with the (nonsignificant) 12 ± 18 ms increase in priming for RTs, overall the data provide evidence that when there is no cognitive overload, sustained attentional processing on the prime and/or expectancy contributes to priming at the long SOA with the .25 RP. 3.4. Does cognitive load reduce expectancy priming with the .75 RP? ITI (cognitive load) had virtually no effect on the expectancybased priming that was presumably occurring with the .75 RP at the 1200 ms SOA. That is, the 43 ± 16 ms priming effect for the 400 ms ITI was virtually identical to the 47 ± 14 ms priming effect for the 2500 ms ITI [t(110) = .37, SE = 10.62, p = .71]. This is surprising because (a) expectancy, which requires attention, should be reduced by the increased cognitive load produced by the short ITI, and (b) the short ITI seemed to have eliminated sustained attentional processing on the prime and expectancy at the long SOA when the RP was .25. However, Kane and Engle’s (2003) goalmaintenance framework offers a plausible account for this finding.

That is, when working memory is taxed by short ITIs, the frequently occurring related prime–target pairs in the .75 RP lists repeatedly serve as external reminders that the participants should maintain the goals of sustaining prime activation or of generating expectancies. However, these goals are not maintained with cognitive load in the .25 lists, which do not provide these frequent reminders. The claim that a high RP provides ‘‘external support” for maintaining the task-relevant goals of sustaining prime activation via attentional processing of the prime even when cognitive load from the short ITI taxes working memory capacity (WMC) is supported by Kane and Engle’s (2003) findings. They compared Stroop interference for high and low WMC individuals as a function of the proportion of incongruent trials in the session. For errors, low WMC participants showed significantly more Stroop interference from an incongruent color word (relative to a letter string baseline) than did high WMC participants when the proportion of color-word trials that were incongruent with the to-be-named ink color was low (.25); however, low WMC participants showed no greater interference than high WMC participants when that proportion was high (100%). This suggests that low WMC participants were just as able as high WMC participants to maintain the goal ‘‘ignore the word and identify the color” when the high proportion of incongruent trials served as repeated reminders to maintain that goal, but neglected that goal when the low proportion of incongruent trials only provided infrequent reminders to maintain that goal. (See also de Jong, 2000, 2001, for conceptually similar effects occurring for older adults in visual attention and task-switching paradigms.) Our foregoing extension of Kane and Engle’s (2003) analysis can also explain how the 400 ms ITI could have increased cognitive load, yet not increase RTs and errors. In our extension, we argued that the cognitive load from the short, 400 ms ITI undermined the maintenance of the goals of using attentional resources to sustain prime activation or to generate an expectancy in the .25 list but was not severe enough to also deplete the attentional processing of the prime associated with that goal when that goal was being maintained by the repeated ‘‘goal reminders” provided by the frequently occurring related prime–target pairs in the .75 RP list. Because the participant’s primary goal was to respond rapidly and accurately to the target, the target processing operations associated with that goal should have been the least likely to have resources strategically re-allocated away from them. Hence, given that the cognitive load imposed by the short, 400 ms ITI was not great enough to affect the mental operations associated with the secondary goal of attentional processing of the prime as long as that goal was being maintained, it is not surprising that it did not affect the mental operations associated with the primary goal of responding rapidly and accurately to the target. 3.5. Questionnaire data on RP estimates Five participants failed to provide an RP estimate. The mean RP estimates for the remaining participants are displayed in the lefthand portion of Table 2 as a function of RP and ITI. A betweengroups 2 (RP)  2 (ITI) ANOVA revealed that RP estimates were 15 ± 6% greater with the .75 RP (60 ± 4%) than with the .25 RP

Table 2 Post-task questionnaire data. ITI

400 ms 2500 ms ITI effect

RP estimates (%)

Ignore estimate

.25 RP

.75 RP

RPE

.25 RP

.75 RP

43 ± 5.5 45 ± 5.5 2 ± 7.1

56 ± 5.5 63 ± 5.5 7 ± 8.6

13 ± 7.5 18 ± 8.2

2.18 ± .18 1.98 ± .18 .20 ± .26

2.04 ± .18 1.84 ± .18 .20 ± .25

RPE .14 ± .25 .14 ± .26

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[44 ± 4%; F(1, 215) = 30.41, MSe = 429.92]. Although participants underestimated the .75 RP and overestimated the .25 RP (and to similar degrees, likely due to a tendency for estimates to be biased towards a 50% estimate), the fact that there was a significant effect of RP shows that participants were nevertheless aware that the RP was above or below 50%. The main effect of ITI and the RP  ITI interaction were not significant for the RP estimate data. These data suggest that participants who received the short ITI (and presumably experienced more cognitive load) were aware of the RP to the same degree as those who received the long ITI. This validates a necessary assumption of our analysis that the frequent occurrence of related trials in the .75 RP lists served as continuous reminders that participants should maintain the goals of sustaining prime activation via attentional processing of the prime or of engaging strategically mediated priming mechanisms such that these goals were maintained even when the short ITI increased cognitive load. That the RP estimates were highly similar for the low RP lists for both ITIs suggests that the absence of expectancy at the long SOA with the shorter ITI was not due to participants’ lack of knowledge (that primes and targets were sometimes related). Rather it was due to their not acting on this knowledge because they did not have sufficient cognitive resources to maintain the goal of using attentional prime processing. 3.6. Questionnaire data regarding ignoring the prime Notwithstanding our foregoing arguments concerning how the increased cognitive load created by the short, 400 ms ITI affected priming and the phenomenologically based face validity that presenting trials every 400 ms led to more cognitive load than presenting them every 2500 ms, one still might be concerned as to whether shortening the ITI actually depleted attentional resources. This concern can be addressed by the self-report data on how often participants ignored the prime. Overall, 51 participants reported that they rarely ignored the prime (a 1 response), 119 reported they sometimes ignored it (a 2 response), and 53 reported they often ignored it (a 3 response). (One participant failed to provide an RP estimate.) The means for the ‘‘ignoring” ratings are displayed in the left-hand portion of Table 2 as a function of RP and ITI. Participants reported ignoring the prime significantly more frequently at the 400 ms ITI (2.11) than at the 2500 ms ITI (1.91) [t(221) = 2.17, SE = 0.09, p =.03]. This is congruent with the claim that the increased cognitive load associated with the 400 ms ITI curtailed attentional processing of the prime. However, it is problematic for our analysis that participants in the 400 ms ITI/.25 RP group did not report ignoring the prime more frequently than participants in the 2500 ms ITI/.25 group. One speculative interpretation of this is that participants understood the query as asking for the frequency with which they noticed the prime rather than the frequency with which they attentionally and strategically processed the prime, and that they were more likely to retrospectively notice the prime when the prime and target were related, thereby accounting for the equivalent RPEs for the ‘‘ignoring the prime” ratings for the two ITIs. A separate analysis revealed that frequent ignoring was negatively correlated with long-SOA priming across both RPs and both ITIs [r(222) = .21, p = .002], but was not correlated with shortSOA priming (r(222) = .01, p = .91]. To explore this effect further, an ANOVA with SOA as a within-participants factor and ‘‘Ignoring Estimate” (1, 2, or 3) as a group factor was conducted on the priming effects for RTs. The SOA  Ignoring Estimate interaction was significant [F(2, 220) = 3.65, MSe = 2075.02], reflecting that priming decreased as the ignoring estimates increased (1 = 47 ms, 2 = 27 ms, and 3 = 14 ms) at the 1200 ms SOA [F(2, 220) = 5.05, MSe = 2914.74] but not at the 160 ms SOA (1 = 17 ms, 2 = 13 ms, and 3 = 18 ms) [F(2, 220) = 0.39, MSe = 1401.00, p = 0.68]. These

data suggest that ‘‘noticing” the prime, which increases as RP increases and is presumably a necessary precursor to attentional/ strategic processing of the prime, has no effect on ASA priming at the short SOA but does influence attentionally mediated priming at the long SOA.

4. General discussion It is widely believed that when attentional resources are not being used to sustain prime activation via attentional processing of the prime or to engage strategically mediated priming mechanisms, ASA from a prime decays within 1 s or less in a standard lexical decision task in which the silently read prime and its related target are not separated from each other by intervening unrelated items. However, as delineated in Section 1, the empirical support for this belief has been ambiguous. That is, prior results could be explained either by ASA actually not decaying or by sustained attentional processing of the prime or expectancy operating even when the RP is low, thereby concealing the decrease in priming that results from rapidly decaying ASA when these attentional sources of priming are not operating. The present results resolve this issue and reveal that ASA does indeed decay within 1200 ms, but only under conditions unfavorable to the operation of strategic/attentional priming (i.e., when cognitive load is increased by a rapid pacing of the trials and a low RP of .25 is used). It is necessary to use a low, .25 RP to reveal ASA decay because even when cognitive load is increased by rapidly presented trials in .75 RP lists, the frequently occurring related prime–target pairs serve as repeated external reminders that participants should maintain the goal of using the attentional resources that remain to sustain prime activation and/or to generate an expectancy. However, when the short ITI increases cognitive load, this goal is not maintained in the .25 RP lists, which only intermittently provides these reminders (cf., Kane & Engle, 2003). Our findings also imply that cognitive load may have dissociable effects on goal maintenance (cf. de Jong, 2000, 2001; Kane & Engle, 2003) and the mental processes necessary to attain a goal. That is, when the RP is .25 and there are too few related prime–target pairs to serve as frequent external reminders to maintain the goals of sustaining prime activation via attentional processing of the prime or of engaging strategically mediated priming mechanisms, increased cognitive load from the short ITI eliminates attentional priming by undermining maintenance of these goals. However, when the RP is .75, plentiful related prime–target pairs serve as continual external reminders to maintain the goals of sustaining prime activation via attentional processing of the prime or of engaging strategically mediated priming mechanisms. Apparently, when these goals are maintained, increased cognitive load from a short ITI is not great enough to reduce attentional resources below the level needed to instigate attentional prime processing and/or implement strategic priming mechanisms. Clearly, future research should address the generality of ITI effects on priming as well as the effects of alternative methods of inducing cognitive load. (See Neely & Kahan, 2001, for a review of the few studies that have used such alternative methods.) Such effects are of importance because they provide a crucible for testing automatic/strategic two-process models of priming and for distinguishing the role of attention in goal maintenance and the mental operations necessary to attain a goal. Our data also suggest that even a low RP of .25 is sufficient to support attentional/strategic priming at a 1200 ms SOA if attentional resources are not being depleted by the cognitive demands of responding to rapidly presented trials. In support of the assumption that strategic priming occurs with a low RP in the .2 to .25 range, O’Connor, Hutchison and Neely (2008) reported a significant

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increase in semantic/associative priming when the RP increased from 0.07 to 0.20 with SOAs of 600 ms and 1200 ms. It is also important to note that our finding that a cognitively demanding short ITI eliminated priming at the 1200 ms SOA with an RP of .25 cannot be accounted for by the shortened ITI’s having reduced the initial level of semantic activation instead of (or as well as) having reduced strategic/attentional priming. This account does not work because we obtained significant and statistically equivalent 12–17 ms priming effects at our 160 ms SOA regardless of the RP and ITI. Because our RP and ITI manipulations were shown to affect priming at the long, 1200 ms SOA when strategic/attentional priming mechanisms can operate, the fact that they did not affect priming at the short, 160 ms SOA suggests that (a) priming at the 160 ms SOA is being mediated by ASA and not by attentional mechanisms, (cf., Neely, 1977; Posner & Snyder, 1975) and (b) the initial level of semantic activation produced by the prime is independent of attentional resources. However, it must be acknowledged that our priming effects were numerically small at the 160 ms SOA. Thus, we cannot be certain that activation decay would have been complete within 1200 ms had our 160 ms SOA priming effects been larger. Nor can we be certain decay was complete for the somewhat small priming effects we observed here because it is risky to ‘‘accept” the null hypothesis. Notwithstanding these caveats, with the level of priming that we obtained with our materials and our 160 ms SOA as a baseline, we obtained unambiguous evidence that ASA does indeed decay (at least partially) within 1200 ms when no other item intervenes between the prime and target and conditions are unfavorable to the operation of strategic/attentional priming mechanisms. Although we have thus far focused on the role that the strategic mechanism expectancy might play in concealing the decay of ASA, it is also possible that another strategic mechanism, semantic matching (see Neely, 1977; Neely & Keefe, 1989; Neely et al., 1989), could be doing so as well. Unlike ASA and expectancy, which are initiated when the prime is presented, semantic matching is not initiated until after the target appears. During the time that participants are processing the target, doing a spelling check and then selecting which response to make, the semantic matching mechanism determines if the target is related to the prime that precedes it. Because nonword targets are typically derived from words that are unrelated to their preceding primes, knowledge that the target is related to its prime provides strong evidence that the target is a word. To the degree that the probability that a target is a nonword given that it is unrelated to its prime (called the nonword ratio by Neely et al., 1989) is greater than the overall probability of a nonword, knowledge that the target is unrelated to its prime provides evidence that the target is likely to be a nonword. If the nonword ratio is high, for unrelated target-prime pairs the semantic matching mechanism gives rise to a bias to respond ‘‘nonword,” which lengthens ‘‘word” RTs following unrelated word primes, thereby producing a priming effect. Because target–prime relatedness by itself only provides information regarding whether the target is a word or a nonword but not how it is pronounced, semantic matching is utilized for lexical decisions but not in pronunciation. This explains why at a long SOA, backward priming (prime: hop; target: bell) occurs in the lexical decision task but not in pronunciation (see Kahan, Neely, & Forsythe, 1999, for a summary of backward priming effects). Whenever the probability of a nonword target is held constant across variations in RP, there is a perfect confounding between the nonword ratio and RP. In the present experiments in which the overall probability of nonword targets was .43 for both the .25 and .75 RPs, the corresponding nonword ratios were .5 and .75. Because the .16 backward target-to-prime associative strength (Nelson et al., 1998) was significantly greater than 0 [t(79) = 7.01 SEM = .02, p < .001)], the significant RP effects at the long SOA for both ITIs could in part

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be due to semantic matching as well as expectancy. They could also be due to other retrospective priming mechanisms such as episodic prime retrieval (e.g., Bodner & Masson, 2001). But even if semantic matching or some other retrospective priming mechanism were contributing to our long-SOA priming effect6, because these retrospective priming mechanisms presumably consume attentional resources (see Tse & Neely, 2007a, for some evidence that semantic matching consumes attentional resources) our major point remains unchanged: when (a) attentional resources are not available to maintain the goals of engaging a strategic priming mechanism (be it expectancy or a retrospective mechanism) or of sustaining the prime’s activation and (b) a low RP does not provide sufficient reminders to maintain those goals, ASA from a prime decays within 1200 ms in the standard semantic-priming paradigm. In our conceptual analysis of prospective priming, we have distinguished between two general ways in which attentional resources could contribute to priming at a long SOA. One way is that they are used to fuel the aforementioned strategic priming mechanisms of expectancy and semantic matching; the other is that they are allocated to sustaining prime activation. The latter possibility was introduced to explain why Neely (1977) failed to find evidence of ASA decay from a prime during a 2000 ms interval in which participants were using the prime to generate an expectancy for targets unrelated to the prime. That is, when participants were using the prime BODY to generate an expectancy for ‘‘building part” targets, inhibition was less to the same degree across SOAs ranging from 250 to 2000 ms for unexpected, related targets (BODY-stomach) than for unexpected, unrelated targets (BODY-robin). Although this suggests that ASA from BODY to stomach had not detectably decayed during 2000 ms, an alternative explanation was that the rehearsal/ reactivation of ‘‘BODY” in the rehearsed ‘‘BODY-BUILDING” instruction could have resulted in the decaying ASA of ‘‘body parts” having been refreshed/reactivated in close temporal proximity to the target’s appearance, such that the initial decay would not have been observed. An interesting issue, which to our knowledge has not been previously considered, is whether in the standard priming paradigm the priming effects that have been attributed to expectancy are in actuality being generated by this activation-maintenance mechanism rather than an active expectancy for specific targets such as that postulated in Becker’s (1980) theoretical analysis and adopted by Neely and Keefe (1989) in their three-process theory of priming. We believe that this interesting possibility should be examined in future research. But once again, even if expectancy is merely a maintenance of activation via prolonged attentional processing of the prime, because this also consumes attentional resources our major point remains unchanged: in the standard semantic-priming paradigm in which no other item intervenes between the prime and its related target, ASA decays within 1200 ms in the absence of attentional processing of the prime. The decay of ASA has also been investigated using nonstandard priming procedures in which unrelated words separate the prime and its related target. For example, Balota and Paul (1996) had participants silently read two primes and compared priming for ankle cat DOG to priming for cat ankle DOG. Decay of ASA is inferred from priming in the latter condition being less than priming in the former condition. Balota and Paul tested both pronunciation and lexical decision tasks and data from both tasks suggested that ASA 6 Our discussion of semantic matching focuses on long-SOA priming because a signature of semantic matching, the nonword facilitation effect (faster RTs to a nonword target when it follows a word prime relative to when it follows a neutral XXXX prime), does not occur at a short SOA. (See Neely, 1991, for a review.) But even if semantic matching did contribute to our short-SOA priming, if the increase in cognitive load produced by the short ITI eliminated semantic matching at the long SOA, it should have also eliminated it at our short SOA as well. That it did not suggests that our short-SOA priming was not produced by semantic matching or any other retrospective priming mechanism that consumes attentional resources.

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partially decays within 300 ms when an unrelated prime intervenes between the related prime and target. In a pronunciation task, when the SOA between the first related prime and the target was 400 ms Masson (1995) found a +3.3 ms priming effect (p = .08, one-tailed) in the cat ankle DOG condition. Although he did not include the ankle cat DOG condition as a baseline for assessing the magnitude of ASA decay, he did find a significant +13 ms priming effect in a cat xxxx DOG condition. This suggests that the reduced priming obtained in the cat ankle DOG condition was due to interference rather than decay per se. Masson (1995) interpreted this result within a connectionist model that assumes that short-term semantic priming is produced by an overlap in the semantic features of the prime and target rather than to ASA. (However, see Dalrymple-Alford & Marmurek, 1999, for some concerns about this account.) When overt responses are made to all primes in the intervening-unrelated-prime paradigm and RTs to the primes are included in the decay time, the results depend on the type of processing performed on the primes (and targets). When the primes and targets are all read aloud, ASA partially decays within 735 ms (Joordens & Besner, 1992); when lexical decisions are made to the primes and targets, priming completely decays within 650 ms in a lexical decision task (McNamara, 1992). However, in a lexical decision task with pseudohomophonic nonwords (e.g., brane), which induce deep semantic processing of all items, priming still occurs when up to 12 s filled with 3–8 intervening unrelated primes separates the related prime and target, and all primes are overtly responded to (Joordens & Becker, 1997; Tse & Neely, 2007b). If this very longterm priming effect were based on ASA (which we do not believe it is), it would suggest that the decay rate of ASA seems to depend on how deeply the prime word is processed. But even if this were so, it would not mean that the initiation of ASA demands attentional resources, as some (e.g., Stolz & Besner, 1999) have argued. That is, although ASA occurs to the same degree independently of attentional resources, once ASA is initiated, its perseverance can be prolonged by additional deep semantic processing or its decay can be hidden by the overlaid effects of attentional priming mechanisms, such as expectancy or semantic matching. (See Neely & Kahan, 2001; Tse & Neely, 2007a, for a similar point.) Although we have focused on ASA as the automatic mechanism underlying priming at short SOAs, we must acknowledge an alternative compound-cuing mechanism postulated by Ratcliff and McKoon (1988). According to their account, participants use a cue combining the prime and target (with more weight given to the target) to access memory and then determine target lexicality based on the familiarity of the compound cue. Because words are generally more familiar than nonwords, a highly familiar cue can be given a quick word response, whereas a highly unfamiliar cue can be given a quick nonword response (cf., Balota & Chumbley, 1984). Priming occurs because cues containing semantically/associatively related words are more familiar than cues containing unrelated words. Although compound cuing shares some of the properties of semantic matching (e.g., it can account for backward priming and presumably is not utilized in pronunciation because the familiarity of the compound cue does not provide information as to how the target should be pronounced), Ratcliff and McKoon intended that compound cuing be considered as a replacement for ASA. Although the concept of decay does not fit neatly within the compound-cuing framework, one could argue that the greater is the amount of time that separates the prime and target, the less likely it is that a compound cue would be formed between them. If our short ITI did indeed reduce attentional resources as we have argued, our results could be construed as showing that attentional resources are needed to form a compound cue between a prime and target when their onsets are separated by 1200 ms or more but not when they are separated by only 160 ms.

In focusing on ASA as the mechanism responsible for automatic priming effects, we have assumed that the short ITI had its effects on priming via the depletion of attentional resources. An alternative account is that ITI does not deplete attentional resources but rather affects how participants temporally group the primes and targets (cf., Neill, 1997; Neill & Valdes, 1992) and that temporal grouping could affect mechanisms that produce priming via ‘‘retrospective” retrieval of the prime when the target is presented (e.g., episodic prime retrieval, Bodner & Masson, 2001; semantic matching, Neely & Keefe, 1989; Neely et al., 1989; compound cuing, Ratcliff & McKoon, 1988). Here we focus on temporal grouping of the prime and target without delineating the details of how these various retrospective mechanisms actually give rise to priming. The basic idea (cf., Neill & Valdes, 1992) is that the likelihood that two events will be grouped (retrieved) together depends on the temporal proximity of these two events compared to the temporal proximity of each of them to other preceding events. When one adds the 420 ms warning signal interval to the ITI, the prime followed the response to the prior target by 820 or 2920 ms for the 400 and 2500 ms ITIs, respectively. Thus, the 1200 ms SOA/ 400 ms ITI condition is the only SOA/ITI condition for which the prime is temporally closer to the target that preceded it than it is to the target that followed it. A probable result of this is that the prime in this condition is less likely to be temporally grouped with its target than in the other three SOA/ITI conditions and this should lead to reduced priming. Thus, this account easily explains the reduction in priming we observed with the 400 ms ITI and 1200 ms SOA when the RP was .25. However, we did not observe such a reduction when the RP was .75, which seems contrary to the prediction of the temporal grouping account. Nevertheless, the temporal grouping hypothesis can also explain why the 400 ms ITI did not reduce priming at the long SOA when the RP was .75 RP by making an assumption highly similar to the assumption we added to our cognitive load interpretation to account for this. Specifically, it can be assumed that the large number of related primes and targets in the .75 RP list served as frequent reminders to override the natural tendency to group the current prime with the temporally closer prior target and instead group it with the current target so as to facilitate performance on the frequently related prime–target trials. A more serious challenge to the temporal grouping hypothesis seems to come from the ‘‘frequency of ignoring primes” ratings. Whereas our cognitive load account easily accommodates lower ratings for the 2500 ms ITI than for the 400 ms ITI, it is unclear what the temporal grouping hypothesis predicts. One possible and incorrect prediction is that these ratings are not influenced by which of the two targets (the immediately preceding one or the immediately following one) the prime gets temporally grouped with. Another possibility is that primes were reported as being more frequently ignored when they were grouped with the immediately preceding target rather than with the immediately following target and that a high RP decreases the former grouping. This would account for our findings that the frequency of ignoring the prime ratings were higher for the short ITI than for the long ITI and for the low RP than for the high RP, if one makes the plausible assumption that the high RP enhances temporal grouping of the target with its immediately preceding prime. However, as does our cognitive load account, the temporal grouping hypothesis incorrectly predicts an RP  ITI interaction such that the frequency of ignoring the prime ratings should be especially high for the 400 ms ITI/.25 RP condition. As noted earlier, our cognitive load account can handle the equivalent frequency of ignoring the prime ratings in the .25 RP lists for the 400 ms and 2500 ms ITIs by making the ad hoc assumption that participants understood the frequency of ignoring the prime query as asking for the frequency with which they noticed the prime rather than the frequency with

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which they attentionally and strategically processed the prime. It is not clear to us what ad hoc assumption could be added to the temporal grouping hypothesis that would allow it to predict the equivalent frequency of ignoring the prime ratings in the .25 RP lists for the 400 ms and 2500 ms ITIs and at the same time predict the main effects of RP and ITI that were observed. Nor is it clear how the temporal grouping hypothesis can handle our result showing that ratings of how often the prime was ignored were negatively correlated with priming at the long SOA but not at the short SOA. This is easily accommodated by our cognitive load account, which assumes that attentional resources are needed for long-SOA priming but not short-SOA priming, which is being produced by ASA. Thus, we believe our cognitive load account provides a more parsimonious explanation for our results than does a temporal grouping hypothesis. Before closing it is important to note that in a lexical decision task with pseudohomophonic nonwords (e.g., brane), which induce deep semantic processing of all items, priming still occurs over a 12 s prime-to-target interval filled with 3–8 overt lexical decisions to intervening unrelated primes (Joordens & Becker, 1997; Tse & Neely, 2007b). This long-term semantic priming effect cannot be easily accommodated by ASA, which based on the present results would be very unlikely to perseverate for 12 s, even when the prime is deeply processed. Nor can it be easily accounted for by compound cuing because it seems highly unlikely that a compound cue would contain up to 8 items. Joordens and Becker (1997) interpreted their long-term priming effects as supporting the idea that priming is produced by a connectionistic learning mechanism. However, it is not clear to us how this mechanism can account for the complex four-way interaction that was obtained in our results. Thus, until it can be shown that this connectionist learning mechanism can account for the full array of results that is rather easily accommodated by the ASA mechanism, we believe that the most prudent approach is to assume that short-term priming is mediated by ASA (see McNamara, 2005, for a review of the evidence favoring the ASA account over the compound-cuing account) and that long-term priming is mediated by a connectionist learning mechanism. If this approach is taken, the present results can be interpreted as showing that ASA decays within 1200 ms when sufficient attentional resources are not allocated to the goal of maintaining the semantic activation that automatically occurs when a word is presented.

5. Conclusion The effect of cognitive load (ITI) on long-SOA semantic priming has both methodological and theoretical implications. Regarding priming methodology, if the goal is to isolate automatic priming from strategic priming, one should use a low RP in conjunction with a short ITI to increase cognitive load so as to better ensure that the obtained priming effect is indeed automatic. Also, by using a short ITI one reduces the length of the testing session, which can be important for fMRI and event-related-potential experiments. It is especially important to use a short ITI for procedures using a long SOA, because the present results (and those of O’Connor, Hutchison & Neely, 2008) suggest that decreasing the RP to .25 may not be sufficient to eliminate attention-driven priming in the standard priming paradigm. In the theoretical domain, virtually all theories that have postulated ASA have assumed that ASA decays in less than 1 s even though the extant data have not strongly supported that assumption. What the present results suggest is that under conditions in which (a) deep semantic processing of the prime is not required, (b) cognitive load from rapidly presented trials depletes attentional resources and (c) the RP is low and does not provide external sup-

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port for maintaining the goal to sustain activation from the prime and/or engage strategic priming mechanisms, ASA decays within 1200 ms in the standard semantic-priming paradigm with silently read primes even when no other items intervene between the prime and target.

References Anderson, J. R. (1983). The architecture of cognition. Cambridge, MA: Harvard University Press. Balota, D. A., & Chumbley, J. I. (1984). Are lexical decisions a good measure of lexical access? The role of word frequency in the neglected decision stage. Journal of Experimental Psychology: Human Perception and Performance, 10, 340–357. Balota, D. A., Cortese, M. J., Hutchison, K. A., Neely, J. H., Nelson, D., & Simpson, G. B., et al. (2002). The English Lexicon Project: A web-based repository of descriptive and behavioral measures for 40,481 English words and nonwords . Balota, D. A., & Paul, S. T. (1996). Summation of activation: Evidence from multiple primes that converge and diverge within semantic memory. Journal of Experimental Psychology: Learning, Memory, and Cognition, 22, 827–845. Becker, C. A. (1980). Semantic context effects in visual word recognition: An analysis of semantic strategies. Memory and Cognition, 8, 493–512. Bodner, G. E., & Masson, M. E. J. (2001). Prime validity affects masked repetition priming: Evidence for an episodic resource account of priming. Journal of Memory and Language, 45, 616–647. Burke, D. B., White, H., & Diaz, D. L. (1987). Semantic priming in young and older adults: Evidence for age constancy in automatic and attentional processes. Journal of Experimental Psychology: Human Perception and Performance, 13, 79–88. Dalrymple-Alford, E. C., & Marmurek, H. C. (1999). Semantic priming in fully recurrent network models of lexical knowledge. Journal of Experimental Psychology: Learning, Memory, and Cognition, 25, 758–775. de Groot, A. M. B. (1984). Primed lexical decision: Combined effects of the proportion of related prime–target pairs and the stimulus-onset asynchrony of prime and target. The Quarterly Journal of Experimental Psychology, 36A, 253–280. de Jong, R. (2000). An intention-activation account of residual switch costs. In S. Monsell & J. Driver (Eds.), Attention and performance XVIII: Control of cognitive processes (pp. 357–376). Cambridge, MA: MIT Press. de Jong, R. (2001). Adult age difference in goal activation and goal maintenance. European Journal of Cognitive Psychology, 13, 71–89. den Heyer, K., Briand, K., & Dannenbring, G. L. (1983). Strategic factors in a lexicaldecision task: Evidence for automatic and attention-driven processes. Memory and Cognition, 11, 374–381. Hutchison, K. A. (2007). Attentional control and the relatedness proportion effect in semantic priming. Journal of Experimental Psychology: Learning, Memory, and Cognition, 33, 645–662. Hutchison, K. A., Neely, J. H., & Johnson, J. D. (2001). With great expectations, can two ‘‘wrongs” prime a ‘‘right”. Journal of Experimental Psychology: Learning, Memory, and Cognition, 27, 1451–1463. Joordens, S., & Becker, S. (1997). The long and short of semantic priming effects in lexical decision. Journal of Experimental Psychology: Learning, Memory, and Cognition, 23, 1083–1105. Joordens, S., & Besner, D. (1992). Priming effects that span an intervening unrelated word: Implications for models of memory representation and retrieval. Journal of Experimental Psychology: Learning, Memory, and Cognition, 18, 483–491. Kahan, T. A., Neely, J. H., & Forsythe, W. (1999). Dissociated backward priming effects in lexical decision and pronunciation tasks. Psychonomic Bulletin and Review, 6, 105–110. Kane, M. J., & Engle, R. W. (2003). Working-memory capacity and the control of attention: The contributions of goal neglect, response competition, and task set to Stroop interference. Journal of Experimental Psychology: General, 132(1), 47–70. Loftus, E. F. (1973). Activation of semantic memory. American Journal of Psychology, 86, 331–337. Masson, M. E. J. (1995). A distributed memory model of semantic priming. Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 3–23. McNamara, T. P. (1992). Theories of priming: I. Associative distance and lag. Journal of Experimental Psychology: Learning, Memory, and Cognition, 18, 1173–1190. McNamara, T. P. (2005). Semantic priming: Perspectives from memory and word recognition. New York: Psychology Press. Neely, J. H. (1977). Semantic priming and retrieval from lexical memory: Roles of inhibitionless spreading activation and limited-capacity attention. Journal of Experimental Psychology: General, 106, 226–254. Neely, J. H. (1991). Semantic priming effects in visual word recognition: A selective review of current findings and theories. In D. Besner & G. W. Humphreys (Eds.), Basic processes in reading (pp. 264–336). Hillsdale, NJ: Erlbaum. Neely, J. H., & Kahan, T. A. (2001). Is semantic activation automatic? A critical reevaluation. In H. L. Roediger, J. S. Nairne, I. Neath, & A. M. Surprenant (Eds.), The nature of remembering: Essays in honor of Robert G. Crowder (pp. 69–93). Washington, DC: American Psychological Association. Neely, J. H., & Keefe, D. E. (1989). Semantic context effects on visual word processing: A hybrid prospective/retrospective processing theory. In G. H.

136

J.H. Neely et al. / Acta Psychologica 133 (2010) 127–136

Bower (Ed.). The psychology of learning and motivation (Vol. 24, pp. 207–248). New York: Academic Press. Neely, J. H., Keefe, D. E., & Ross, K. L. (1989). Semantic priming in the lexical decision task: Roles of prospective prime-generated expectancies and retrospective semantic matching. Journal of Experimental Psychology: Learning, Memory, and Cognition, 15, 1003–1019. Neill, W. T. (1997). Episodic retrieval in negative priming and repetition priming. Journal of Experimental Psychology: Learning, Memory, and Cognition, 23, 1291–11305. Neill, W. T., & Valdes, L. A. (1992). Persistence of negative priming: Steady state or decay? Journal of Experimental Psychology: Learning, Memory, and Cognition, 18, 565–576. Nelson, D. L., McEvoy, C. L., & Schreiber, T. A. (1998). The University of South Florida word association, rhyme, and word fragment norms. . O’Connor, P. A., & VanVoorhis, B. A. (2004). Working memory capacity predicts strategic, but not automatic semantic priming. Poster presented at the 45th Annual Meeting of the Psychonomics Society, Minneapolis, MN. O’Connor, P. A., Hutchison, K. A., & Neely, J. H. (November, 2008). Relatedness proportion effects in semantic priming occur even for relatedness proportions below .25. Poster presented at the 49th annual meeting of the Psychonomic Society, Chicago, IL.

Posner, M. L., & Snyder, C. R. R. (1975). Attention and cognitive control. In R. L. Solso (Ed.), Information processing and cognition: The Loyola symposium. Hillsdale, NJ: Erlbaum. Ratcliff, R., & McKoon, G. (1988). A retrieval theory of priming in memory. Psychological Review, 95, 385–408. Schneider, W., Eschman, A., & Zuccolotto, A. (2002). E-prime user’s guide. Pittsburgh: Psychology Software Tools. Stolz, J. A., & Besner, D. (1999). On the myth of automatic semantic activation in reading. Current Directions in Psychological Science, 8, 61–65. Stolz, J. A., Besner, D., & Carr, T. H. (2005). Implications of measures of reliability for theories of priming: Activity in semantic memory is inherently noisy and uncoordinated. Visual Cognition, 12, 284–336. Stolz, J. A., & Neely, J. H. (1995). When target degradation does and does not enhance semantic context effects in word recognition. Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 596–611. Tse, C.-S., & Neely, J. H. (2007a). Semantic priming from letter-searched primes occurs for low- but not high-frequency targets: Automatic semantic access may not be a myth. Journal of Experimental Psychology: Learning, Memory, and Cognition, 33, 1143–1161. Tse, C.-S., & Neely, J. H. (2007b). Semantic and repetition priming effects for Deese/ Roediger-McDermott (DRM) critical items and associates produced by DRM and unrelated study lists. Memory and Cognition, 35, 1047–1066.