THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY2006, 59 (7), 1224 – 1236
Heinrich-Heine-Universita¨t, Du¨sseldorf, Germany
Performance of 28 schizophrenic patients and 28 matched controls was compared in an auditorypriming task. A large auditory negative priming effect was obtained for the patients as well as forthe control group, and the size of the negative priming effect was approximately the same for bothgroups. Under the same conditions, positive or repetition priming for the patients was enhancedcompared to that of the control group. The present findings from an auditory priming task are con-sistent with a growing body of evidence from the visual domain showing normal rather than reducedor eliminated negative priming in schizophrenic patients.
The negative priming phenomenon manifests
1977), negative priming reflects the operation of
itself in slowed-down or more error-prone
an inhibitory attentional selection mechanism
reactions to recently ignored stimuli compared to
that prevents access of recently ignored objects to
those for control stimuli that are unrelated to the
overt responses by suppressing competing distrac-
previous stimuli (for reviews, see Fox, 1995;
tor input. This inhibitory mechanism enables
May, Kane, & Hasher, 1995; Neill, Valdes, &
more efficient responding to the current target
Terry, 1995; Tipper, 2001). Several models are
under normal circumstances, but causes a delay
currently available to explain the negative
in responding when, as in a negative priming labo-
priming phenomenon. Of these models, the so-
ratory task, the previously ignored (and, hence,
called distractor inhibition model has a special
supposedly suppressed) distractor becomes the
status not only because it is historically the oldest
model that explains this phenomenon but also
This attentional explanation of the negative
because it suggests that the negative priming
priming phenomenon is interesting for schizo-
paradigm may be an appropriate task for testing
phrenia research because attentional impairment
predictions of loss-of-inhibition theories of the
is one of the fundamental cognitive deficits associ-
changes in cognitive functioning induced by
ated with schizophrenia. In particular, increased
schizophrenia, ageing, and other conditions.
distractibility in the presence of irrelevant infor-
According to the version of this model proposed
mation has been widely attributed to disrupted
by Tipper (1985; see also Dalrymple-Alford &
mechanisms responsible for the direction and
Budayr, 1966; Houghton & Tipper, 1994; Neill,
control of attention—that is, to the impaired
Correspondence should be addressed to Axel Buchner, Institut fu¨r Experimentelle Psychologie, Heinrich-Heine-University,
D-40225 Du¨sseldorf, Germany. Email: [email protected]
The research reported in this article was supported by a grant from the Deutsche Forschungsgemeinschaft (Bu 945/2–1). # 2006 The Experimental Psychology Society
functioning of inhibitory attentional mechanisms
priming, but only in subgroups of schizophrenic
(e.g., Frith, 1979; McGhie, 1977; McGhie &
patients. For instance, normal negative priming
Chapman, 1961). With respect to the negative
has been reported for chronic outpatients but not
priming paradigm, the assumption of impaired
for acutely psychotic schizophrenic inpatients
inhibitory attentional mechanisms in schizo-
(S. Park, Lenzenweger, Pu¨schel, & Holzman,
phrenia predicts less or no slow-down of the
1996; S. Park, Pu¨schel, Sauter, Rentsch, & Hell,
reactions of schizophrenic patients to previously
2002; see also Salo, Henik, Nordahl, & Robertson,
ignored distractors compared to those of normal
2002), and for medicated but not for unmedicated
controls, provided that the distractor inhibition
schizophrenic patients (Salo, Robertson, &
model is valid. The negative priming task itself
Nordahl, 1996; Salo, Robertson, Nordahl, &
appears particularly useful for testing the loss-of-
Kraft, 1997), as well as conversely for unmedicated
inhibition assumption in schizophrenia because a
but not for medicated schizophrenic patients
cognitive deficit is expressed in improved perform-
(David, 1995). In contrast, Moritz et al. (2001)
ance (no reaction slow-down), rather than impo-
reported that symptomatology and neuroleptic
verished performance, which is usually explained
medication did not moderate the size of the nega-
by a generalized cognitive deficit rather than a
tive priming effect. Interestingly, they noted that
specific inhibitory attentional impairment.
procedural details may determine whether or not
negative priming is observed in schizophrenic
Claridge (1989) started off such a research pro-
patients. In their study, control participants and
gramme and reported reduced negative priming
schizophrenic patients did not differ in terms of
in a group of schizophrenic patients compared to
negative priming when the prime presentation dur-
that in a control group. This finding was inter-
ation was 250 ms, but schizophrenic patients failed
preted as being consistent with the assumption
to show any priming when primes were presented
that schizophrenia implies a reduction in the ability
for 100 ms and were followed by a pattern mask,
of the cognitive system to inhibit and suppress
as in Beech et al. (1989). Moritz et al. argued that
previous findings of no or reduced negative
However, subsequent research has produced
priming in schizophrenic patients may have been
different and somewhat inconsistent results. For
due to a procedural artifact—that is, the very
instance, Laplante, Everett, and Thomas (1992)
short presentation durations combined with
did not find reduced negative priming in schizo-
pattern masking, which simply may have impaired
phrenic patients relative to depressive patients
the patients’ processing of the prime distractor.
and healthy control participants.1 Parallel results
have recently been reported in several studies
Wagner (2002) reported normal levels of identity
(Baving, Wagner, Cohen, & Rockstroh, 2001;
negative priming in schizophrenic patients in a
Moritz, Jacobsen, Mersmann, Kloss, & Andresen,
task that required selection by stimulus identity,
2000; Roesch-Ely, Spitzer, & Weisbrod, 2003;
but the patients showed reduced spatial negative
Wagner, Loeper, Cohen, & Rockstroh, in press).
priming when spatial position was incidental and
Other researchers also found preserved negative
not task relevant. However, MacQueen, Galway,
1 The reported negative priming effects were descriptively large for schizophrenic patients classified as negative (255 ms, N ¼ 10)
or positive (100 ms, N ¼ 8), for depressive patients (228 ms, N ¼ 21), and for control participants (69 ms, N ¼ 35). An analysis ofvariance (ANOVA) showed that the size of the effect did not differ significantly between groups. However, when the authors testedwhether the effect was significant within a particular group, statistically significant results emerged only for the depressive and controlparticipants. The problem with these group-specific tests and the conclusions drawn from them is that the sample size and, hence,the statistical power were so much smaller in the schizophrenic than in the other groups that results favouring the statistical nullhypothesis (“no negative priming”) are highly expected on purely methodological grounds and must not be interpreted as indicatingno negative priming in the schizophrenic groups.
THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 2006, 59 (7)
Goldberg, and Tipper (2003) reported reduced
to classify, by an appropriate key press, the
spatial negative priming of schizophrenic patients
attended tone as originating from an instrument
compared to control participants when spatial
or an animal. Each trial consisted of a prime pair
position was relevant and not incidental.
and a probe pair of stimuli. Trials were separated
purpose of the present research was to add
A preliminary version of this task using experi-
further evidence to the body of available findings
mental parameters that had previously been found
on the relation between negative priming and
appropriate for use with elderly participants
schizophrenia. In particular, we wanted to extend
(Buchner & Mayr, 2004) was implemented in a
the range of available findings from the visual to
pilot study to check its adequacy for a clinical
the auditory domain. While this empirical exten-
sample with diagnoses of schizophrenia. In this
sion into a new sensory modality may be regarded
pilot experiment, the participants’ task was to clas-
as interesting in its own right, another purpose for
sify the attended tones as belonging to either the
moving into the auditory modality was to provide
“wind instrument” (flute, trumpet, and saxophone)
for a potentially more sensitive test of the hypoth-
or the “string instrument” (piano, balalaika, and
esis of reduced negative priming in schizophrenia.
pizzicato violin) category by responding with an
Specifically, Banks, Roberts, and Ciranni (1995)
appropriate key press. Each trial consisted of a
argued that attending to a tone while avoiding
prime pair and a probe pair of stimuli, with a cue –
auditory distraction must operate almost entirely
target interval of 500 ms and an interval of 500 ms
by internal processing mechanisms. Visual selec-
between reaction to prime and the following probe
tion, in contrast, may be supported by peripheral
mechanisms such as eye or head movements.
The main result of the pilot study was that the
Auditory selection by internal distractor inhibition
clinical sample had great difficulties performing a
may thus be regarded as much more demanding,
task that had been shown to be clearly feasible
leaving little or no room for compensating for
for elderly participants. In general, the patients
any inhibitory deficits. As a consequence, reduc-
produced huge numbers of errors. What is more,
tions in the efficiency of inhibitory mechanisms
of the 46 clinical participants, 12 prematurely
may be more clearly apparent in the auditory
terminated the experiment because they felt over-
than in the visual domain, so that group differ-
taxed. For the experiment reported here, therefore,
ences in negative priming may be expected to be
stimuli were selected from categories that were
stronger and more reliable in the auditory than
easier to distinguish (instruments and animal
in the visual domain. Furthermore, given the
sounds), and the temporal parameters between
widespread occurrence of auditory hallucinations
experimental events were modified to ensure that
in schizophrenia, the auditory domain seemed
patients could comply with the task without
especially relevant for the investigation of
being overtaxed, so as to avoid serious and
attentional mechanisms in this patient group.
unwanted selection bias. It also seemed importantto take these steps in order to avoid possible per-ceptual problems that might prevent the patientsfrom fully processing the prime distractors, since
this is thought to be a variable that could explainthe observation of no or reduced negative
priming in schizophrenic patients (cf. Moritz
In the task used here, participants heard pairs oftones displayed via headphones. One tone was
presented to each ear. A click indicated the ear
Participants for the clinical group were 28 psychia-
that had to be attended. Participants were asked
tric patients (10 female) who were recruited from
THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 2006, 59 (7)
three different psychiatric hospitals and met the
1,949), and the distribution of dosages was posi-
diagnostic criteria for schizophrenia according to
tively skewed. A total of 10 patients also received
ICD-10 (Dilling, Mombour, & Schmidt, 1993).
other medication (tranquillizers, sedatives, or anti-
Six of the patients were outpatients.2 Diagnoses
depressants), and 6 were also taking anticholinergic
were established by experienced clinicians at the
medication. Controls were 28 healthy participants
hospitals. Furthermore, one of the authors and the
(10 female) recruited mainly from the university
responsible ward psychiatrists and psychologists
staff and without a history of psychiatric illness.
carefully screened all available clinical records in
Controls and schizophrenia participants were
order to exclude patients with previous or concur-
matched for age, gender, and years of education
rent diagnoses that were incompatible with an
as a measure of overall intellectual level, premorbid
unambiguous diagnosis of schizophrenia. For an
in the case of the patients (see Table 1). None of
unambiguous diagnosis of schizophrenia, only
the participants used hearing aids, and controls
patients without double psychiatric diagnoses,
and patients did not differ with respect to their
schizoaffective disorders, or potentially drug-
self-reported hearing ability (using a 3-point scale
induced psychoses were accepted. On average the
with “above average”, “normal”, and “below
first known diagnosis of schizophrenia had
average”), z ¼ 1.38, p . .17. None of the patients
occurred 5.9 years (minimum, 0.5 years; maximum,
and control persons was older than 45 years so
26 years; SD ¼ 5.7) before the time at which the
that possible confusion with age-related effects on
experiment was conducted. Thus, the sample of
the size of the negative priming phenomenon
patients had the advantage of being relatively hete-
(cf. Verhaeghen & De Meersman, 1998) could be
rogeneous with respect to the duration of their
excluded, although in retrospect this additional
illness, rendering it less likely that the findings of
control may have been unnecessary given that a
this experiment could be due to the specific charac-
more recent meta-analysis suggests that there is
teristics of a highly selective group of patients. The
no age-related difference in negative priming
responsible clinicians were requested to rate the
patients on the Brief Psychiatric Rating Scale’s
All participants were paid for their participation
(BPRS, Overall & Gorham, 1962) German
and gave informed consent previous to their
version (Collegium Internationale Psychiatriae
participation in the experiment. They were also
Scalarum, 1996) based on their daily interaction
explicitly informed that they could terminate the
with patients and previous clinical interviews.
experiment at any time if they so wished.
The total sum of the 18 individual ratings can beinterpreted as an approximate total pathology
score. For our clinical sample, the BPRS total
The stimuli were six digitized tones, which could
score mean was 48 (SD ¼ 9.9). All patients
be identified and categorized easily and unambigu-
received neuroleptic medication. Chlorpromazine
ously as “musical instruments” (piano, guitar, and
equivalents were calculated for 27 patients accord-
clarinet) or “animal sounds” (duck, lamb, and
ing to Jahn and Mussgay (1989) for conventional
frog). Each tone was 300 ms long, complete with
attack and decay. The participants heard the
Woods (2003) for newer atypical antipsychotic
tones over earphones that were fitted with high-
medication. The mean daily dosage in chlorproma-
isolation hearing protection covers and plugged
zine units was 449.6 (minimum, 41; maximum,
directly into an Apple PowerBook computer.
2 Note that removing the outpatients from the patient group did not change any of the statistical conclusions reported in this
article, except for one secondary result pertaining to the supplementary analysis of the error data: The overall difference in errorsbetween ignored repetition (IR) and ignored repetition control (IRC) trials for the entire sample of schizophrenic patients andhealthy control participants was just barely statistically significant when the outpatients were included in the sample, and it narrowlymissed the preset level of statistical significance when the six outpatients were removed (see the Results section).
THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 2006, 59 (7)
Table 1. Data characterizing the matched patient and control groups
Trials consisted of a prime and a probe pair of
the IR and its corresponding IRC trial. The
stimuli. There were four basic types of trial:
same holds for the AR and their corresponding
ignored repetition trials (IR), ignored repetition
control trials (IRC), attended repetition trials
For each prime and each probe pair of stimuli,
(AR), and attended repetition control trials (ARC).
only combinations of tones from the two cat-
Each IR trial corresponded to one IRC trial in
egories (animal sound or musical instrument)
terms of the tone configuration except for the
were used in order to necessitate real selection
ignored prime, which differed but was taken
for each category. In other words, combinations
from the same category. Similarly, each AR trial
of stimuli from one category were never presented
corresponded to one ARC trial in terms of the
together. Combining all six different tones in the
tone configuration except for the attended prime,
way illustrated in Table 2 yields 72 unique trials
which differed but was taken from the same cate-
of each type: IR, IRC, AR, and ARC, resulting
gory. This is illustrated in Table 2. If negative, or
in a total of 288 different trials. Of this original
positive, priming occurs with this arrangement of
pool of stimuli, a subset of 144 combinations (36
corresponding trials, then it must be due to pro-
per trial type) was selected in such a way that
cesses operating at the level of the stimulus iden-
the absolute frequencies of the different tones
tity of the tone and cannot be due to processes
were equal overall as well as within each trial
related to the response category. To illustrate,
type. Furthermore, the frequencies of the combi-
the guitar tone is ignored in the IR prime pair
nations of attended and ignored tones were identi-
example given in Table 2, and the piano tone is
ignored in the corresponding IRC prime pair.
An important difference between IR and IRC
Both belong to the same category of instruments.
trials on the one side and AR and ARC trials on
If the reaction to the guitar tone was slowed
the other is that the required response always
in the IR relative to the IRC probe pair, then
changed in the former and remained the same in
the processes causing the slow-down must operate
the latter types of trial. For the experimental pro-
on the stimulus identity of the ignored prime,
cedure, this has the desired consequence that the
because that is the only difference between
required reaction to the attended probe could not
Table 2. Examples of stimulus configurations
THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 2006, 59 (7)
be predicted from the prime. For the data analysis,
to-be-attended probe tone was presented either
the consequence is that IR trials can only be
to the same ear as the prime or to the other ear.
compared to IRC trials, and AR trials can only
The relation of the to-be-attended prime and
probe location was varied in blocks. The block-wise presentation was a consequence of the pilot
study that had shown that schizophrenic patients
The task was introduced as a tone categorization
find it difficult to cope with attended primes and
task. Extensive practice was provided in order to
probes appearing unpredictably at the same or at
familiarize the participants with the task. They
different ears. One half of the participants in
were first introduced to the tones and the reaction
each group first received the block of randomly
keys by hearing each tone individually, and by
ordered trials in which the attended primes
reacting to single tones for each category presented
and probes were presented to the same ear, fol-
first to one ear, and then to the other. A metro-
lowed by the remaining trials in which the
nome click indicated the ear at which the tone
attended primes and probes were presented to
would be presented. Following this, participants
different ears. For the other half or the participants
were asked to react to 24 randomly presented
in each group this sequence of blocks was reversed.
single tones. The last part of the practice session
The ordering of blocks was counterbalanced over
introduced the actual experimental task. Here
subjects. Within each block, the ear at which the
two different tones were presented to the right
to-be-attended prime was presented was thus
and left ear, and the preceding 20-ms metronome
randomly selected but predicted the ear of the
click now indicated which ear was to be attended
to-be-attended probe. Within each trial type, the
to (determined at random). Participants reacted
attended primes and probes were presented to
to consecutive pairs of stimuli—that is, a prime
the same ear on 18 trials, whereas attended
pair and a probe pair. After a 1,000-ms cue –
primes and probes were presented to different
target interval, a pair of tones was presented, one
ears for the other 18 trials. This implies that
to the left and one to the right ear. The interval
on IR trials, the ignored prime changed location
in the former case, but did not change location
500 ms. Participants reacted to the attended tone
by pressing, as quickly as possible, the “instru-
Prime or probe reactions faster than 100 ms and
ment” or the “animal” key, depending on the
slower than 4,000 ms were counted as invalid, and
category to which the tone belonged.
the entire trial was repeated. After each trial,
The experiment itself consisted of 144 trials,
participants were given visual and acoustic feed-
each of which was composed of a prime and a
back on the correctness of their reactions to the
probe pair of tones as in the final phase of the prac-
prime and probe (visual feedback indicated
tice session. The participants initiated each trial
whether the reactions to prime and probe had
at their own pace. A trial began with a brief
been correct or false, and acoustic feedback was
countdown followed by the click indicating the
“very good” for two correct responses, “almost”
ear on which the to-be-attended tone would be
for one correct response, and “too bad” for two
presented. The instructions emphasized correct-
incorrect responses). A summary feedback about
ness, but reactions were also to be made as
error percentages and average reaction times was
quickly as possible. The interval between partici-
provided after every 12th trial, and to further
pants’ reactions and the click preceding the probe
motivate the participants they were informed of
pair of tones was 500 ms. The probe tone pair
how they had performed compared to the previous
was presented with the same temporal parameters
block of 12 trials. Once again, after the summary
feedback, participants continued the experiment
The to-be-attended ear for the prime pair of
at their own discretion. On completion of
stimuli was always selected at random. The
the experiment, participants were given the
THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 2006, 59 (7)
opportunity to be informed about the purpose of
Probe reaction times were evaluated only for trialsin which both the probe and the prime reactions
were correct. The means of participants’ average
The design consisted of two 2 Â 2 Â 2 subdesigns.
reaction times and the corresponding error rates
The ignored repetition subdesign comprised IR
are presented in the upper and lower panels of
versus IRC trials as the levels of the within-
subject priming factor and same versus different
Patients reacted more slowly than controls.
presentation sides of the attended prime and probe
Reaction times on IR trials were longer than
as the levels of the within-subject presentation side
reaction times on IRC trials, and they were
factor. The attended repetition subdesign differed
longer when the attended prime was presented to
by having AR versus ARC trials as the levels of the
a different ear from that of the attended probe.
priming factor. Both subdesigns also comprised
Corresponding to these descriptive data, a 2 Â 2
the two levels, patients versus matched control
 2 analysis of variance (ANOVA) with partici-
persons, of the quasi-experimental between-
pant group (schizophrenic patients vs. controls)
subjects variable. The primary dependent variables
as between-subjects variable, and priming (IR vs.
were participants’ reaction times, but error proba-
IRC) as well as presentation side (same vs. differ-
ent) as within-subject variables showed significant
A power analysis with respect to the negative
main effects of patient group, F(1, 54) ¼ 11.22,
(or positive) priming effect showed that given
p , .001, of priming, F(1, 54) ¼ 64.71, p , .001,
a sample size of n ¼ 28 in each of the two
and of presentation side, F(1, 54) ¼ 68.17,
groups (i.e., N ¼ 56), and a ¼ .05, effects of size
p , .001. The critical interaction of participant
group and priming was not significant, F(1, 54) ¼
z ¼ .45 (cf. Cohen, 1977) could be detected
with a probability of (1 – b) ¼ .95 (the sample
0.22, p . .64, as were all other interactions,
negative priming effect actually turned out to be
Fs(1, 54) , 1.90, p . .17. Follow-up t tests
much larger than this assumed population value,
showed that negative priming was significant for
both the schizophrenic patients, t(27) ¼ 5.68,
28, and a ¼ .05, effects of size d ¼ .80 (“large”
p , .001, and the control participants, t(27) ¼
effects in terms of the conventions suggested by
5.73, p , .001. In terms of the reaction times,
Cohen, 1977) could be detected with a probability
the mean and standard deviation of the negative
of (1 – b) ¼ .91 for the one-tailed test of whether
priming effect was somewhat larger for the
negative priming is smaller in patients than in
patients (M ¼ 88 ms, SD ¼ 82 ms) than for the
controls. Assuming a population effect size of
controls (M ¼ 78 ms, SD ¼ 72 ms). In terms of
d ¼ .80 for the difference in negative priming
standardized effect sizes, the sample effects for
between patients and controls seemed conservative
patients and control participants were quite large
and reasonable given that the sample effect sizes in
studies that reported an overall difference between
patients and control participants, respectively.
these groups were typically much larger and
This very close match across groups can be con-
sidered strong evidence in favour of the hypothesis
that the negative priming effect does not differ
The level of a was set to .05 for all analyses
with the reaction time data although only the
3 The power calculations were conducted using the G.Power program (Buchner, Faul, & Erdfelder, 1996; Erdfelder, Faul, &
THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 2006, 59 (7)
Figure 1. Reaction times (upper panel) and error rates (lower panel) as a function of trial type and presentation side for schizophrenic patientsand control participants. The error bars depict the standard errors of the means.
difference in errors between IR and IRC trials was
reactions on ARC trials. Again patients showed
statistically significant, F(1, 54) ¼ 4.45, p ¼ .04.
slower reaction times than the control persons,
Turning to the positive priming subdesign, we
and reaction times were longer when the attended
find that reactions on AR trials were faster than
primes and probes were presented to different ears.
THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 2006, 59 (7)
A 2 Â 2 Â 2 ANOVA with participant group
important conceptual replications and extensions
(patients vs. control participants) as between-
of previous findings of normal visual negative
subjects variable, and priming (AR vs. ARC) as
priming in schizophrenic patients (e.g., Baving
well as presentation side (same vs. different) as
et al., 2001; Moritz et al., 2001; Roesch-Ely
within-subject variables showed significant main
et al., 2003; Wagner et al., in press). If we also con-
effects of participant group, F(1, 54) ¼ 14.27,
sider that the original demonstration of reduced
p , .001, of priming, F(1, 54) ¼ 39.55, p ,
.001, and of presentation side, F(1, 54) ¼
(Beech et al., 1989) seems to have been con-
90.35, p , .001. There was also an interaction
founded with atypically impoverished presentation
between the participant group and priming,
conditions (cf. Moritz et al., 2001), then the con-
F(1, 54) ¼ 4.66, p , .04, reflecting the fact that
clusion suggests itself that attentional deficits
positive priming was larger for schizophrenic
associated with schizophrenia may not after all
be reflected in a paradoxically “faster” performance
than for control participants (M ¼ 55 ms, SD ¼
on ignored repetition trials. Instead, schizophrenic
patients seem to show a slow-down in reactions
scores were significantly different from zero,
to previously ignored distractors in the negative
t(27)s . 3.06, p , .01. The interaction between
priming paradigm, which is comparable to that
priming and presentation side was also significant,
found with healthy participants. Does this neces-
F(1, 54) ¼ 26.71, p , .001, indicating that positive
sarily have to be counted as evidence against the
priming was larger when attended primes and
assumption of an impaired functioning of inhibi-
probes were presented to the same ear (M ¼
tory attentional mechanisms in schizophrenia?
133 ms, SD ¼ 105 ms) than when they were pre-
sented to different ears (M ¼ 35 ms, SD ¼
First, according to the inhibition model of
142 ms). No other interactions were significant,
negative priming (Dalrymple-Alford & Budayr,
1966; Houghton & Tipper, 1994; Neill, 1977)
With respect to the error data, there were
the characteristic slow-down when reacting to a
significant main effects of priming, F(1, 54) ¼
probe that was previously ignored is caused by
16.14, p , .001, and of presentation side, F(1,
the need to overcome the inhibition imposed
54) ¼ 21.55, p , .001. An interaction between
during prime selection. Therefore, one possible
participant group and presentation side, F(1,
conclusion is that the kinds of inhibitory processes
54) ¼ 4.30, p , .05, reflected that the presentation
thought to be impaired in schizophrenia (“a defect
side effect was larger for schizophrenic patients
in the mechanism that controls and limits the
(M ¼ .06, SD ¼ .20) than for control participants
contents of consciousness”, cf. Frith, 1979, p. 225)
are actually different from those involved in thesuppression of perceptual distractors in negativepriming tasks. Indeed, it may be an oversimplifica-
tion to conceive of only one homogeneous type of
The main result of the present experiment is that
Second, one could assume that negative priming
showed the same amount of negative priming in
tasks do not really measure inhibition at all, and
this auditory priming task, as is most obvious
indeed there are alternative explanations of the
from the very close match of these groups in
basic negative priming phenomenon of which
terms of the standardized negative priming
feature mismatch, temporal discrimination, and
effect. Considering that reductions in the effi-
episodic retrieval appear to be most relevant (see
ciency of inhibitory mechanisms may be more
Fox, 1995; May et al., 1995; Milliken, Joordens,
clearly apparent in the auditory than in the visual
Merikle, & Seiffert, 1998; Neill et al., 1995). For
domain (Banks et al., 1995), these results represent
instance, J. Park and Kanwisher (1994) assumed
THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 2006, 59 (7)
that negative priming was caused by a feature mis-
remembered nonresponse information conflicts
match between prime and probe—that is, by a
with the response requirements implied by the
change in the bindings of symbol identities to
probe target and in that way slows down the
locations between the prime and probe. In the
probe responses. If such low-capacity, short-term
present experiments, bindings of tone identities
retrieval as specified by this model were intact in
(e.g., the piano tone) to locations (e.g., the left
schizophrenia, then we would expect the pattern
ear) changed when, on ignored repetition trials,
of findings reported in the present experiment.4
the prime distractor presented to one ear was also
Thus, the only conclusion we can come to from
the probe target subsequently presented to the
the present findings is that negative priming as
other ear (mismatch condition). In contrast, the
an empirical phenomenon is not reduced in
bindings stayed the same on those ignored rep-
schizophrenia. We cannot reject, based on these
etition trials on which prime and probe distractors
findings, the assumption that attentional inhibi-
were presented to the same ear (no mismatch con-
tory functions are impaired in schizophrenia,
dition). Obviously, the size of the negative priming
either because there may be more than one type
effect was completely unaffected by whether or not
of inhibitory process, or because the characteristic
a mismatch occurred, adding the present study to
slow-down to previously ignored stimuli in nega-
the growing body of evidence suggesting that
tive priming tasks actually may not measure inhi-
feature mismatching does not play an important
bition. We have reason to believe that the latter
role in negative priming (Baylis, Tipper, &
alternative is quite unlikely, because existing evi-
Houghton, 1997; Buchner & Mayr, 2004;
dence suggests that inhibitory processes are at
Buchner & Steffens, 2001; Buchner, Steffens, &
least to some extent involved in the generation of
Berry, 2000; Fuentes, Humphreys, Agis, Carmona,
& Catena, 1998; Milliken, Tipper, & Weaver,
present experimental task (Buchner & Steffens,
1994; Tipper, Weaver, & Houghton, 1994).
2001). However, it could well be that negative
In contrast, the episodic retrieval model
priming tasks do not yield the best measure of
suggested by Neill and colleagues (Neill &
inhibition, or at least not an exclusive one.
Valdes, 1992; Neill et al., 1995; Neill, Valdes,
Another result worth mentioning is that the
Terry, & Gorfein, 1992) could explain the
positive priming effects were significantly larger
current data pattern. According to this model the
in schizophrenic patients than in healthy controls.
probe target cues the retrieval of the perceptually
This replicates a data pattern first reported by
similar prime display in which the distractor
Baving et al. (2001; see also Wagner et al., in
representation contains the information that no
press) for a situation with relatively long stimulus
response was (to be) made to that stimulus. This
presentations in which both the prime and the
4 The so-called temporal discrimination account (Milliken, Joordens, Merikle, & Seiffert, 1998) may, in principle, also explain
the present data, but past experiments suggest that the discrimination account does not seem adequate to explain negative priming inthe present paradigm, and it also does not add to the understanding of negative priming phenomena beyond what can already beexplained by the distractor inhibition and episodic retrieval models (Buchner & Steffens, 2001; Buchner, Zabal, & Mayr, 2003)which is why it is not mentioned in the main text. Within this framework, two classes of process are assumed to occur when aprobe response is generated. First, if the probe can be categorized as old, then automatic processes are likely to determine the responsein that the prior action is simply retrieved and executed. This explains fast responses on attended repetition trials. Second, if the probetarget is categorized as new so that prior learning is an inappropriate basis for action, complete perceptual analysis of the stimulus isnecessary in order to arrive at a response. This takes more time than simply retrieving a recent response and corresponds to controltrials. A third situation is given on ignored repetition trials. The target has been presented as part of the prime display, but it has notbeen fully attended. Thus, the probe target is somewhat familiar so that it cannot be quickly categorized as new, but it is also not quitefamiliar enough to be immediately categorized as old. According to Milliken et al. (1998), “this ambiguity in the temporal discrimi-nation process for ignored repetition trials is presumed to underlie negative priming” (p. 210). There is no reason to assume that theambiguity should be eliminated in schizophrenia, so that, in principle, this account could explain intact negative priming inschizophrenia.
THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 2006, 59 (7)
probe stimuli required a response. As Baving et al.
Baving, L., Wagner, M., Cohen, R., & Rockstroh, B.
also noted, positive priming is normal or reduced
(2001). Increased semantic and repetition priming
with short stimulus presentations and without
in schizophrenic patients. Journal of Abnormal
the requirement to respond to the primes. Thus,
just as with negative priming, the relative size of
Baylis, G. C., Tipper, S. P., & Houghton, G. (1997).
Externally cued and internally generated selection:
the positive priming effect in schizophrenic
Differences in distractor analysis and inhibition.
patients seems to depend, among other things,
on whether the conditions for perceiving the
Perception and Performance, 23, 1617 – 1630.
Beech, A. R., Powell, T., McWilliam, J., & Claridge, G.
The investigation of the causes of such positive
(1989). Evidence of reduced “cognitive inhibition” in
priming or repetition effect has a long history.
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It dates back to the work of Bertelson (e.g.,
Bertelson, 1961, 1965) who already argued that
Bertelson, P. (1961). Sequential redundancy and speed
the effect was primarily caused by processes
in a serial two-choice responding task. Quarterly
located at the level of response mechanisms and
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