Modality-specific and amodal sources of interference in the attentional blink.

Abstract

When two masked targets (T1 and T2) are visually or auditorily presented in rapid succession, processing of T1 produces an attentional blink (AB)--that is, a transient impairment of T2 identification. The present study was conducted to compare the relative impact of masking T1 and T2 between vision and audition. Within a rapidly presented sequence, each of the two verbal targets, discriminated by their offset (Experiment 1) or their onset (Experiment 2), could be followed by either a single item, acting as a mask, or a blank gap. Masking of T2 appeared to be necessary for the occurrence of the AB for both the visual and the auditory modality. However, whereas masking of T1 affected the expression of the visual AB in both experiments, the same effect was observed in the auditory modality only when the targets varied at the onset. These results provide further evidence that processing auditory and visual information is restricted by similar attentional limitations but also suggest that these limits are constrained by properties specific to each sensory system.

Full text

Page 1

Copyright 2008 Psychonomic Society, Inc. 1000
When interacting with its environment, an organism is
constantly confronted with an overwhelming amount of
perceptual input from all the senses, continuously chang-
ing over time and space. The efficient management of this
flow of information is under the control of selective at-
tention, and this process can be viewed as the cognitive
capacity of preferentially processing stimulations that are
the most relevant as guides to action, while concurrently
disregarding unwanted stimuli (see, e.g., Pashler, 1998).
Many studies have shown that attentional mechanisms are
limited as to the number of stimuli they can handle simul-
taneously, as reflected, for example, by breakdowns in an
individual’s ability to efficiently process multiple stim-
uli presented closely in time (see, e.g., Shapiro, 2001).
Temporal- processing deficits have been observed over a
wide range of paradigms within different sensory modali-
ties or even across modalities. In the present study, we ex-
amined whether temporal constraints on the processing
of auditory information are functionally similar to those
observed in the visual domain. We did so by using the
attentional blink (AB) phenomenon, which is a manifes-
tation of the temporal limitations on human information
processing, to contrast audition and vision.
The AB occurs when two to-be-processed masked tar-
gets are presented in rapid succession (Raymond, Shapiro,
& Arnell, 1992). This is true whether the two targets are
embedded within a rapid stream of distractors (a proce-
dure known in the visual domain as rapid serial visual
presentation; see, e.g., Broadbent & Broadbent, 1987;
Weichselgartner & Sperling, 1987) or followed only by a
single posttarget stimulus (a procedure usually referred as
the two-target paradigm; see, e.g., Duncan, Ward, & Sha-
piro, 1994; Ward, Duncan, & Shapiro, 1997). The typi-
cal expression of the phenomenon is a transient deficit
in reporting the second (T2) of two targets when it fol-
lows the first target (T1) by less then 500 msec. A well-
accepted explanation of the AB suggests that processing
of T2 is impaired while limited attentional resources are
committed to the processing of T1 (see Shapiro, Arnell,
& Raymond, 1997). Such a constraint in the temporal dis-
tribution of attention has been extensively investigated in
vision, but far fewer studies have been carried out in the
auditory domain. One key feature of the visual AB phe-
nomenon is the determinant role of target masking (see
Enns, Visser, Kawahara, & Di Lollo, 2001). When applied
to the auditory AB, the concept of masking also appears to
contribute to the phenomenon (e.g., Vachon & Tremblay,
2005); however, its role seems to be restricted, as com-
pared with the role of masking in the visual AB (e.g., Shen
& Mondor, 2006). Such findings suggest that the function
of masking in the AB would differ according to the modal-
ity, which has important implications for understanding
the nature of the AB phenomenon and the limitations of
temporal processing in both audition and vision.
The investigation of the AB in various sensory mo-
dalities is of great importance, since theoretical models
diverge with regard to the origin of the attentional limita-
tions underlying the phenomenon. Indeed, some models
assume that the AB reflects attentional constraints spe-
cific to each modality (e.g., Duncan, Martens, & Ward,
1997; Soto-Faraco & Spence, 2002) or even that the ef-
fect is restricted to vision (e.g., Potter, Chun, Banks, &
Muckenhoupt, 1998; Shapiro, Raymond, & Arnell, 1994),
whereas others suggest that the AB relies on central and
Modality-specific and amodal sources
of interference in the attentional blink
François Vachon and sébastien tremblay
Université Laval, Quebec City, Quebec, Canada
When two masked targets (T1 and T2) are visually or auditorily presented in rapid succession, processing of
T1 produces an attentional blink (AB)—that is, a transient impairment of T2 identification. The present study
was conducted to compare the relative impact of masking T1 and T2 between vision and audition. Within a
rapidly presented sequence, each of the two verbal targets, discriminated by their offset (Experiment 1) or their
onset (Experiment 2), could be followed by either a single item, acting as a mask, or a blank gap. Masking of T2
appeared to be necessary for the occurrence of the AB for both the visual and the auditory modality. However,
whereas masking of T1 affected the expression of the visual AB in both experiments, the same effect was ob-
served in the auditory modality only when the targets varied at the onset. These results provide further evidence
that processing auditory and visual information is restricted by similar attentional limitations but also suggest
that these limits are constrained by properties specific to each sensory system.
Perception & Psychophysics
2008, 70 (6), 1000-1015
doi: 10.3758/PP.70.6.1000
F. Vachon, f.vachon@umontreal.ca

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Masking in the Visual and auditory aB 1001
site for observing reliable visual AB effects (e.g., Brehaut
et al., 1999; Giesbrecht & Di Lollo, 1998).
Among the theoretical accounts of the AB making
explicit predictions about the influence of masking, one
class of theories refers to a processing bottleneck at the
stage of transferring information from a perceptual stage
to short-term memory (STM). Bottleneck models, such as
the two-stage model (Chun & Potter, 1995) and the cen-
tral interference theory (Jolicœur, 1998, 1999; Jolicœur
& Dell’Acqua, 1998), posit that the AB arises because
the consolidation of T2 into STM—a process assumed
to be capacity limited—is postponed while T1 is being
consolidated. During this delay, the representation of T2
is vulnerable to interference from subsequent stimuli. Ac-
cording to bottleneck models, the role of the T2 mask is
to prevent T2 report by corrupting its representation while
awaiting consolidation (Giesbrecht & Di Lollo, 1998). On
the other hand, the role of masking T1 is to degrade the
target, thereby slowing down its processing. Such an in-
crease in the time needed to process T1 extends the delay
for consolidating T2.
Although the bottleneck models agree that a postper-
ceptual bottleneck is responsible for the AB, they support
different views as to whether the phenomenon will extend
outside the visual modality. Indeed, whereas the two-stage
model confines the bottleneck to visual information pro-
cessing (see Chun & Potter, 2001), the central interfer-
ence theory explicitly predicts the existence of the AB in
audition by locating that bottleneck after the convergence
of the information coming from the different sensory sys-
tems (e.g., Arnell & Jolicœur, 1999).
Masking in the Auditory AB
In the auditory modality, little is known about the role
of target masking, since in only a few studies has masking
within the auditory AB paradigm been directly manipu-
lated (Mondor, 1998; Shen & Mondor, 2006; Vachon &
Tremblay, 2005, 2006). Some authors have claimed that
auditory information is more resilient with regard to inter-
ference from subsequent events than is its visual counter-
part, given the larger capacity and longer duration of the
echoic buffer, relative to iconic memory (Chun & Potter,
2001; Potter et al., 1998). According to this claim, per-
ceptual interference provided by masking would not be an
important factor in the auditory AB. Conversely, Vachon
and Tremblay (2005) showed that when T2 terminated the
auditory sequence, the AB deficit was abolished, suggest-
ing that backward masking was necessary for obtaining
auditory AB effects, as is the case in the visual modality
(see also Shen & Mondor, 2006). Moreover, no AB occurs
in the auditory domain if T2 is masked by integration or if
the T2 mask is delayed long enough to appear after T2 has
acceded to the so-called short-term consolidation stage of
processing (Vachon & Tremblay, 2006), paralleling find-
ings from the visual AB literature (Brehaut et al., 1999;
Giesbrecht & Di Lollo, 1998). In the case of the impact
of masking T1 in the auditory AB, Mondor (1998; Shen
& Mondor, 2006) showed that the removal of T111 from
the auditory sequence had no effect on the size of the AB,
rather then markedly reducing the size of the deficit, as is
amodal processing limitations (e.g., Arnell & Jenkins,
2004; Jolicœur & Dell’Acqua, 1998). However, investi-
gations of the auditory AB do not allow unequivocal con-
clusions about the nature of the phenomenon. Although a
number of studies have provided direct AB comparisons
between the visual and the auditory modalities (e.g., Ar-
nell & Jenkins, 2004; Arnell & Jolicœur, 1999; Arnell &
Larson, 2002; Duncan et al., 1997; Soto-Faraco & Spence,
2002), in none of these has the role of masking been exam-
ined. Since the literature on the auditory AB has revealed
conflicting evidence regarding the role of masking and its
correspondence with the visual modality, in the present
study we sought to uncover the source of such discrepan-
cies by comparing the impact of target masking on the AB
between the auditory and the visual modalities.
Masking in the Visual AB
Despite the well-established postperceptual nature of
the AB (e.g., Martens, Wolters, & van Raamsdonk, 2002;
Shapiro, Caldwell, & Sorensen, 1997; Vachon, Tremblay,
& Jones, 2007; Vogel, Luck, & Shapiro, 1998), the con-
tribution of perceptual interference to the phenomenon is
essential. Within the visual AB literature, most of the stud-
ies have focused on the influence of perceptual interfer-
ence provided by the presence of a single posttarget item,
denoted as a mask. The masking of a target, either T1 or T2,
in a visual sequence usually yields detrimental effects on
the probability of reporting T2 correctly. However, there is
ample evidence that the role of masking T1 in the visual AB
differs from that of masking T2 (see Enns et al., 2001).
T1 masking was recognized early as an important fac-
tor in the visual AB phenomenon (see Raymond et al.,
1992). Replacing the item that immediately followed T1
in the visual sequence (T111) by a blank usually leads to
the attenuation of the visual AB (e.g., Chun & Potter, 1995;
Grandison, Ghirardelli, & Egeth, 1997; Moore, Egeth,
Berglan, & Luck, 1996; Seiffert & Di Lollo, 1997). Back-
ward interference suffered by T1 from the subsequent item
is not the only form of masking that affects the visual AB.
Indeed, even when T111 is omitted, visual AB effects can
be observed if an item is displayed simultaneously with T1,
either spatially superimposed (integration masking) or in
close spatial proximity (metacontrast masking; see, e.g.,
Grandison et al., 1997; Seiffert & Di Lollo, 1997). Nev-
ertheless, the presence of perceptual interference upon T1
does not appear to be necessary to observe the visual AB,
since the effect is reduced but not abolished in the absence
of T1 masking (see Visser, 2007, for a discussion).
On the other hand, the contribution of T2 masking seems
to be essential for the visual AB to occur. In fact, there is
no AB deficit when T2 terminates the sequence (e.g., Gies-
brecht & Di Lollo, 1998; Jolicœur, 1999; Vogel & Luck,
2002). Whereas the type of masking is rather unimportant
for T1, the precise form of masking is critical in the case of
T2. If T2 is masked by integration (i.e., T2 is overlaid by a
nontarget item), its identification is compromised, but the
deficit is not related to the temporal distance between the
two targets (Brehaut, Enns, & Di Lollo, 1999; Giesbrecht
& Di Lollo, 1998). Thus, the presence of at least one item
after the presentation of T2, even delayed, is a prerequi-

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1002 Vachon and treMBlay
here were verbal stimuli. In either the visual or the audi-
tory modality, the participants’ task was to report the iden-
tity of two target syllables. Each of the two target stimuli
was discriminated by either their offset (Experiment 1)
or their onset (Experiment 2). The use of the same task
requirements in both modalities in a within-subjects de-
sign enabled a straightforward comparison of AB patterns
between the auditory and the visual conditions.
The manipulation of masking in the present study con-
sisted of a systematic variation of the presence of a mask
after each target. So, T1 and T2 could be independently
followed by either a mask item or a blank interval of the
same duration. In this way, the contribution of T1 masking
to visual and auditory AB effects could be examined sepa-
rately from that of T2 masking. Following the literature,
visual and auditory AB deficits should occur only when
T2 is masked. If the removal of the whole sequence of dis-
tractors is effective in reducing the influence of perceptual
organization in audition, we should observe an enlargement
of the AB with the addition of a mask after T1 not only in
the visual condition, but also in the auditory condition.
ExpEriMEnt 1
The verbal stimuli employed in Experiment 1 were sim-
ilar to those utilized by Duncan et al. (1997). In either the
visual or the auditory condition, the participants had to re-
port the identity of two target syllables: One was a na’ syl-
lable (either nab or nap), and the other was a co’ syllable
(either cod or cot). Therefore, the discriminating informa-
tion was located at each target syllable’s offset. Given that
the participants in the present study were all native French
speakers, it is noteworthy that the syllables employed here
have no particular meaning in French. Auditory targets
could be masked by the syllable guh, whereas an XXX
string mask could follow visual targets.
Method
participants. Thirty French-speaking adults reporting normal or
corrected-to-normal vision and no hearing problems were recruited
on the campus of Université Laval. They received a small hono-
rarium for their participation in the experiment.
Apparatus. A Pentium PC computer, with a 15-in. (38.1-cm)
VGA monitor and a 16-bit soundcard, was used for presenting stim-
ulus sequences and recording responses. The same computer ran a
Visual Basic 6.0 program for the auditory condition1 and an E-Prime
1.1 program for the visual condition.
Stimuli. In both the visual and the auditory conditions, a stimulus
sequence always contained two target items. One target item was a
na’ syllable (nab or nap), and the other was a co’ syllable (cod or
cot). Each target could be immediately followed by a single non-
target item, denoted as a mask. Figure 1 presents a schematic il-
lustration of the four types of sequence employed in Experiment 1:
(1) T1M1T2M, in which both targets were masked; (2) T11T2M,
in which a mask followed T2 only; (3) T1M1T2, in which only T1
was masked; and (4) T11T2, in which the two targets were pre-
sented with no other item.
Each visual target lasted 80 msec. The visual mask consisted of
the XXX string presented for 150 msec. When absent, the mask
was replaced by a blank frame of 150 msec. All of the letters form-
ing the visual stimuli were capitalized (NAB, NAP, COD, COT, and
XXX) and were presented in 25-point Arial font, subtending ap-
proximately 1.26º of visual angle in height on the computer screen.
observed in vision (e.g., Chun & Potter, 1995; Seiffert &
Di Lollo, 1997). Such a divergence raises some questions
about the equivalence of the AB phenomenon between
modalities and, thus, deserves more attention.
Mondor’s (1998; Shen & Mondor, 2006) findings may
be taken to support the hypothesis that auditory stimuli
are somewhat insensitive to backward interference (e.g.,
Chun & Potter, 2001). However, the results from Vachon
and Tremblay (2005, 2006) strongly suggest that auditory
information is rather sensitive to interference for sub-
sequent stimuli. The failure of Mondor to find an effect
of removing T111 from the auditory sequence may be
explained if the special role played by perceptual orga-
nization in audition is taken into account. The selection
of target stimuli is assumed to be constrained, in part, by
an early automatic perceptual organization stage during
which the auditory system tends to group stimuli on the
basis of their relative similarity (e.g., Bregman, 1990; Cu-
sack & Carlyon, 2003; Mondor & Terrio, 1998; Mondor,
Zatorre, & Terrio, 1998). According to Mondor and Ter-
rio, the “perceptual organization process acts dynamically
over time to determine whether each successive tone is
a member of a larger sequence” (p. 1634). Since tones
grouped at a perceptual level tend to be selected or rejected
as a group, the selection of a target will be more difficult
if it shares perceptual attributes analogous to those of the
other stimuli in the sequence. There is evidence that an
increase of target–distractor similarity within an auditory
sequence reduces accuracy (e.g., Tysiaczny & Mondor,
2005) and lengthens detection time for a target tone (e.g.,
Mondor et al., 1998). Given the high similarity between
T1 and the distractors in Mondor’s (1998) study (T1 was a
pure tone of 4000 Hz embedded within pure tones whose
frequencies ranged from 452 to 3462 Hz), the interference
provided by the whole sequence of distractors may have
exceeded that of the T1 mask, rendering the presence of
the latter obsolete.
the present Study
The following experiments were tailor-designed to
equate testing conditions for T1 and T2 masking and to
compare the AB phenomenon between audition and vi-
sion. In order to isolate the influence of the masks from
that of the whole sequence of distractors, we adopted a
simplified version of the AB paradigm, in which each of
the two targets was followed by a single item (e.g., Brehaut
et al., 1999; Duncan et al., 1994; Ward et al., 1997). Under
visual conditions in which all four items were displayed
at the same spatial location, the results showed a perfor-
mance comparable to that with the traditional stream-like
presentation (e.g., McLaughlin, Shore, & Klein, 2001;
Ward et al., 1997). However, to our knowledge, such a
paradigm has never been used in audition. Hitherto, the
examination of the impact of masking in the auditory
AB has been based solely on studies employing pure and
complex tones (Mondor, 1998; Shen & Mondor, 2006;
Vachon & Tremblay, 2005, 2006). Because these stimuli
have no equivalent in the visual domain, the use of non-
verbal auditory stimuli restricts the comparison with the
visual AB. Thus, the target and nontarget items employed

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Masking in the Visual and auditory aB 1003
participants initiated a trial by a mouse click on a “start” button
displayed on the screen in the auditory session and by pressing the
space bar on the keyboard in the visual session. Each trial began
with the presentation of a fixation cross in the center of the screen
for 500 msec, followed by a delay of 100 msec before the start of the
stimulus sequence. Each trial was 2,100 msec in duration, measured
from the onset of the fixation to the onset of the response prompt.
The participants’ responses were typed in following the presentation
of each set of stimuli, using keys labeled appropriately for the tar-
gets, without time pressure. Under the single-task conditions, there
was a single response identifying the attended target. Under dual-
task conditions, two responses were typed in, in either order.
results
Data in the single-task conditions were pooled over tar-
get syllables (na’ and co’ as single targets) for both T1
and T2. Within the present study, the mean accuracy for
T1 and T2 were calculated regardless of whether or not
the other target was correctly discriminated. However,
the same pattern of data was also found when T2 perfor-
mance was conditional on T1’s being correctly reported.
The mean accuracy for T1 (negative SOAs) and T2 (posi-
tive SOAs) is plotted as a function of task, SOA, and type
of sequence in Figure 2 for the auditory condition and in
Figure 3 for the visual condition.
t1 performance. The mean percentage of correct re-
ports of T1 was submitted to a repeated measures ANOVA
with modality (2 levels), task (2 levels), SOA (3 levels),
and type of sequence (4 levels) as within-subjects factors.
Here and elsewhere in the present study, the Greenhouse–
Geisser procedure was applied on every effect for which
the sphericity assumption was violated. The analysis
showed significant effects of modality [F(1,29) 5 72.22,
p , .001, d 5 3.16], task [F(1,29) 5 27,83, p , .001, d 5
1.96], and SOA [F(2,58) 5 7.99, p , .001, d 5 1.05].
There was also a significant effect of type of sequence
[F(3,87) 5 79.19, p , .001, d 5 3.31], which indicates
All the visual stimuli were white and appeared in the center of a
black background.
Sounds were digitally edited to a 16-bit resolution at a sampling
rate of 48 kHz, using Sound Forge 5.0, and were presented binau-
rally via headphones at approximately 65 dB(A). All the auditory
items were digitally recorded in a male voice. Great care was taken
to produce the vowels at an even pitch and level. Each auditory tar-
get was compressed to a duration of 125 msec. The auditory mask
item was the syllable guh compressed to last 150 msec. These digital
compressions did not decrease the intelligibility of the individual
items. In the absence of the auditory mask, a 150-msec silent gap
followed the target.
Both the visual and the auditory sequences began with the pre-
sentation of T1, chosen at random on each trial between the na’ and
the co’ syllables. T2 was presented following delays of 275, 425,
or 1,025 msec measured from T1 onset to T2 onset (stimulus onset
asynchrony, or SOA). So, even when a T1 mask was absent, T2 never
occurred immediately after T1—that is, at a lag of 1. The identity
of T2 depended on that of T1: If T1 was a co’ syllable, T2 was a
na’ syllable, and vice versa. When presented, the mask followed the
target immediately, with no interstimulus interval.
Design. A within-subjects design was employed with four fac-
tors: modality (visual or auditory), task (single or dual), T1–T2
SOA (275, 425, or 1,025 msec), and type of sequence (T1M1T2M,
T11T2M, T1M1T2, or T11T2). All the participants took part in
two experimental sessions, one for each modality condition; the
order of these sessions was counterbalanced across participants.
Within each session, the participants performed two single-task con-
ditions (one with the instructions to identify the na’ syllable and one
the co’ syllable) and one dual-task condition in which both targets
had to be reported. These conditions were blocked so that there was
one experimental block per task condition. The order of these three
blocks was counterbalanced across participants. T1–T2 SOAs and
types of sequence were randomized from trial to trial within each
block. There were 96 experimental trials per block, preceded by 24
practice trials.
procedure. The participants had to perform a two-alternative
forced choice discrimination; they were told to discriminate between
nab and nap for the na’ syllable and between cod and cot for the
co’ syllable. When performing the auditory session, the participants
were familiarized with the sounds before attempting any trials. The
XXX XXX
T1T2 MaskMask
80 msec 150 msec
NAPCOT
SOA = 425 msecSOA = 425 msec
T1M+T2M
Visual Auditory
“guh” “guh”
T1Mask
125 msec150 msec
T2Mask
“nab”“cod”
T1+T2M
XXX
T1T2 Mask
NAP COT
“guh”
T1 T2 Mask
“nab”“cod”
T1M+T2
XXX
T1T2 Mask
NAPCOT
“guh”
T1MaskT2
“nab”“cod”
T1+T2
T1T2
NAP COT
T1T2
“nab”“cod”
Figure 1. Schematic diagram illustrating the four types of stimulus sequence employed in visual and auditory modalities in Experi-
ment 1: t1M1t2M, t11t2M, t1M1t2, and t11t2. Visual targets were presented for 80 msec and auditory targets for 125 msec.
Mask items lasted 150 msec in both modalities. t2 followed t1 by one of three delays of 275, 425, or 1,025 msec (all examples show a
t1–t2 stimulus onset asynchrony [SOA] of 425 msec).

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1004 Vachon and treMBlay
t2 performance. A 2 3 2 3 3 3 4 repeated measures
ANOVA was performed on T2 accuracy, with modality,
task, SOA, and type of sequence as within-subjects factors.
All the main effects were significant [modality, F(1,29) 5
112.81, p , .001, d 5 3.95; task, F(1,29) 5 104.83, p ,
.001, d 5 3.80; SOA, F(2,58) 5 31.21, p , .001, d 5 2.08;
and type of sequence, F(3,87) 5 125.68, p , .001, d 5
4.16]. The latter effect meant that T2 was reported less ac-
curately when it was followed by a mask. The interaction of
modality and type of sequence was significant [F(3,87) 5
that T1 performance was at its lowest level when T1 was
followed by a mask. The significant modality 3 type of
sequence interaction [F(3,87) 5 34.67, p , .001, d 5
2.19] provided evidence that this detrimental effect of T1
mask on T1 performance was larger in the auditory condi-
tion. The interaction between modality and SOA was sig-
nificant [F(2,58) 5 3.25, p 5 .03, d 5 0.67], as was that
between modality, task, and type of sequence [F(3,87) 5
3.58, p 5 .01, d 5 0.70]. All the remaining effects were
nonsignificant (ps . .07 and ds , 0.47).
0
50
60
70
80
90
100
% Correct
T1+T2
T1M+T2
–1,025–425 –275 275 4251,025
0
50
60
70
80
90
100
% Correct
SOA (msec)
T1+T2M
–1,025 –425 –275275 4251,025
SOA (msec)
Single-task
Dual-task
T1M+T2M
Figure 2. results from the auditory condition in Experiment 1: Mean percentages of correct target responses as a function of task
(single vs. dual), t1–t2 stimulus onset asynchrony (SOA), and type of sequence (t1M1t2M, t11t2M, t1M1t2, and t11t2). posi-
tive SOAs refer to t2, and negative SOAs refer to t1. Error bars represent 95% within-subjects confidence intervals.

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Masking in the Visual and auditory aB 1005
between modality and SOA [F(2,58) , 1, d 5 0.36] or be-
tween modality, SOA, and type of sequence [F(6,174) , 1,
d 5 0.36]. The interaction of task and SOA, which is the
empirical signature of the AB, was significant [F(2,58) 5
15.94, p , .001, d 5 1.48]. Of particular importance for the
purpose of the present experiment is the significant interac-
tion between task, SOA, and type of sequence [F(6,174) 5
5.00, p , .001, d 5 0.83]. This reliable three-way interac-
tion indicates that the relation between task and SOA dif-
fers according to the type of sequence. In the same way, the
42.94, p , .001, d 5 2.43], indicating that the disruptive ef-
fect of the T2 mask was larger in the auditory condition. The
significant task 3 type of sequence interaction [F(3,87) 5
25.89, p , .001, d 5 1.89] revealed lower T2 accuracy with
dual tasks when T2 was masked. The analysis showed re-
liable interactions between task and modality [F(1,29) 5
11.36, p 5 .001, d 5 1.25]; between SOA and type of se-
quence [F(6,174) 5 8.61, p , .001, d 5 1.09]; and between
modality, task, and type of sequence [F(3,87) 5 4.01, p ,
.01, d 5 0.74]. However, there was no significant interaction
0
50
60
70
80
90
100
% Correct
T1+T2T1M+T2
–1,025–425 –275275 4251,025
0
50
60
70
80
90
100
% Correct
SOA (msec)
T1+T2M
–1,025 –425 –275275 425 1,025
SOA (msec)
Single-task
Dual-task
T1M+T2M
Figure 3. results from the visual condition in Experiment 1: Mean percentages of correct target responses as a function of task
(single vs. dual), t1–t2 stimulus onset asynchrony (SOA), and type of sequence (t1M1t2M, t11t2M, t1M1t2, and t11t2). posi-
tive SOAs refer to t2, and negative SOAs refer to t1. Error bars are 95% within-subjects confidence intervals.

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1006 Vachon and treMBlay
However, the present results also reveal discrepan-
cies between the visual and the auditory AB: T1 masking
seemed to modulate T2 deficits only in the visual con-
dition. Masking of T1, although not essential, produces
larger and protracted visual AB effects (see Visser, 2007).
Although a similar trend was observed in the auditory
condition (see Figure 2), the presence of a mask after T1
did not significantly modify the expression of the auditory
AB. This failure to find a modulating effect of T1 mask-
ing on the AB in the auditory condition cannot be attrib-
utable to the inefficient perceptual interference provided
by the mask or the relative insensitivity of auditory items
to masking (see, e.g., Chun & Potter, 2001). In fact, the
presence of a mask after either T1 or T2 in the auditory
condition produced a major drop in overall performance
with both single and dual tasks. Such important mask-
ing effects may have contributed to the failure to show
an effect of masking T1 on the auditory AB. Indeed, T2
accuracy for T11T2M and T1M1T2M was near chance
level at short SOAs, which might partly have prevented
seeing any subtle changes in T2 performance caused by
the presentation of T1 mask.
With regard to overall T1 and T2 performance, the in-
terference produced by the mask appeared to be much
more detrimental in the auditory than in the visual condi-
tion. The disparity highlighted in the present experiment
between audition and vision in relation to the influence of
masking may ensue from a difference in the temporal na-
ture of the auditory and visual stimuli, which could have
modulated the interference provided by the mask. The in-
formation required to discriminate each pair of target syl-
lables used in Experiment 1 (i.e., nab–nap and cod–cot)
was located at the end of the stimuli. In the visual condi-
tion, this crucial information was displayed for the whole
stimulus duration, since the three letters forming the target
syllables were presented simultaneously on the screen. In
the auditory condition, however, the discriminating in-
formation was available solely at the end of the stimu-
lation, given the successive presentation of phonemes in
audition. Since the offset of the target coincided with the
onset of the mask (i.e., no target–mask interval), the time
the discriminating information was accessible within the
sensory buffer tended to be much shorter in the auditory
than in the visual condition. Besides, some studies have
shown that listeners generally require more information
and more time to identify a syllable when the discriminat-
ing information is located at the end, rather than at the
beginning, of the syllable (e.g., Salasoo & Pisoni, 1985;
Wingfield, Goodglass, & Lindfield, 1997).
The effects of masking in the auditory condition can
be accounted for by considering the processes implicated
in interference by masking—that is, interruption and in-
tegration processes (Massaro, 1975; see also Bazana &
Stelmack, 2002). The successive presentation of the mask
and the target yielded the premature interruption of the
processing of the latter. When applied on T2, this form of
masking led to the appearance of the AB. However, the
very close temporal proximity of the mask and the target
syllable in the auditory condition may also have promoted
the integration of the last part of the target, which allows
significant modality 3 task 3 SOA interaction [F(2,58) 5
3.04, p 5 .03, d 5 0.65] points to variations in the expres-
sion of the visual and the auditory AB. However, the four-
way interaction did not reach significance [F(6,174) 5
1.37, p 5 .12, d 5 0.44].
Since AB deficits appear to vary according to the type
of sequence, the relation between task and SOA was ana-
lyzed for each of the four types of sequence separately for
each modality. A stricter alpha level of .01 was used in
order to compensate for the increase in family-wise error
rate. In the auditory condition, the interaction of task and
SOA was significant at T1M1T2M [F(2,58) 5 4.00, p 5
.01, d 5 0.74] and at T11T2M (F 5 3.68, p 5 .01, d 5
0.71) but was far from significant at T1M1T2 and T11T2
(Fs , 1, ds , 0.19). These results reinforce the impres-
sion given by a visual inspection of Figure 2 that auditory
AB-like effects were observed when T2 was masked. In
the visual condition, analysis showed a significant task 3
SOA interaction at T1M1T2M (F 5 12.02, p , .001, d 5
1.29) and at T11T2M (F 5 25.87, p , .001, d 5 1.89).
However, this interaction was not significant at T1M1T2
(F 5 2.19, p 5 .07, d 5 0.55), or at T11T2 (F , 1, d 5
0.22). It appears that, as is suggested by a visual inspec-
tion of Figure 3, there were reliable visual AB-like deficits
when a mask followed T2.
Dual-task cost. To evaluate the contribution of T1
masking on the magnitude of the AB in both the audi-
tory and the visual conditions, the dual-task cost—the dif-
ference in T2 accuracy between single and dual tasks—
was contrasted between conditions in which an AB was
obtained—that is, at T11T2M (T1 mask absent) and
T1M1T2M (T1 mask present), with respect to SOA.
These data were submitted to a 2 (T1 mask) 3 3 (SOA)
repeated measures ANOVA separately for each modal-
ity. In the auditory condition, the main effect of T1 mask
did not reach significance [F(1,29) 5 1.13, p 5 .15, d 5
0.40], and the T1 mask 3 SOA interaction was far from
significant [F(2,58) , 1, d 5 0.33]. Conversely, the main
effect of T1 mask [F(1,29) 5 2.87, p 5 .05, d 5 0.63] and
the T1 mask 3 SOA interaction [F(2,58) 5 2.98, p 5 .03,
d 5 0.64] were significant in the visual condition. When
the dual-task cost was compared between T11T2M and
T1M1T2M at each SOA, a significantly larger dual-task
cost for T1M1T2M was obtained at 425 msec [t(29) 5
3.28, p , .01, d 5 1.22], revealing a protracted visual AB
effect when T1 was followed by a mask.
Discussion
As has been demonstrated before in vision (e.g., Gies-
brecht & Di Lollo, 1998), as well as in audition (e.g., Va-
chon & Tremblay, 2005), the present experiment showed
that the presence of a mask after T2 is a prerequisite for
revealing the AB phenomenon. Moreover, the presence of
visual and auditory time-locked deficits in the T11T2M
condition provides evidence that the sole presence of a
T2 mask with no other distractor is sufficient to produce
reliable visual (see Moore et al., 1996) and auditory AB
effects. The similarities between the impact of visual and
auditory T2 masking suggest that the AB is caused by at-
tentional processes that are independent of modality.

Page 8

Masking in the Visual and auditory aB 1007
gets) for both T1 and T2. The mean accuracy for T1 (nega-
tive SOAs) and T2 (positive SOAs) is presented in Figure 4
for the auditory condition and in Figure 5 for the visual con-
dition as a function of task, SOA, and type of sequence.
t1 performance. A 2 3 2 3 3 3 4 repeated measures
ANOVA was carried out on mean percentages of correct
discrimination of T1, with modality, task, SOA, and type of
sequence as within-subjects factors. The analysis showed
significant main effects of modality [F(1,28) 5 10.04, p ,
.01, d 5 1.20], task [F(1,28) 5 4.11, p 5 .03, d 5 0.77],
and SOA [F(2,56) 5 6.70, p 5 .001, d 5 0.98]. The sig-
nificant main effect of type of sequence [F(3,84) 5 49.27,
p , .001, d 5 2.65] points to a lower T1 accuracy when T1
was masked. This time, the magnitude of the negative im-
pact of masking T1 was similar across modalities [modal-
ity 3 type of sequence, F(3,84) , 1, d 5 0.19]. There was
a significant interaction between SOA and type of sequence
[F(6,168) 5 3.34, p , .01, d 5 0.69], as well as between
modality, SOA, and type of sequence [F(6,168) 5 2.33,
p 5 .04, d 5 0.58]. The latter interaction seems attributable
to an effect of SOA on T1 accuracy restricted to the auditory
T1M1T2M condition. All the remaining effects were not
significant (ps . .14 and ds , 0.43).
t2 performance. T2 accuracy was submitted to a 2
(modality) 3 2 (task) 3 3 (SOA) 3 4 (type of sequence)
repeated measures ANOVA. The main effects of modal-
ity [F(1,28) 5 8.91, p , .01, d 5 1.13], task [F(1,28) 5
192.17, p , .001, d 5 5.24], and SOA [F(2,56) 5 63.81,
p , .001, d 5 3.02] were significant. The significant main
effect of type of sequence [F(3,84) 5 76.01, p , .001, d 5
3.30] indicates that T2 performance was impaired when
T2 was followed by a mask. This detrimental effect of T2
masking was larger in the visual condition [modality 3
type of sequence, F(3,84) 5 11.83, p , .001, d 5 1.30]
and with a dual task [task 3 type of sequence, F(3,84) 5
32.97, p , .001, d 5 2.17]. Except for the interaction be-
tween modality and SOA [F(2,56) 5 1.65, p 5 .10, d 5
0.49], all other interactions reached significance [modal-
ity 3 task, F(1,28) 5 5.31, p 5 .02, d 5 0.87; SOA 3
type of sequence, F(6,168) 5 5.67, p , .001, d 5 0.90;
modality 3 task 3 type of sequence, F(3,84) 5 4.98,
p , .01, d 5 0.84; and modality 3 SOA 3 type of se-
quence, F(6,168) 5 2.29, p 5 .02, d 5 0.57]. The interac-
tion between task and SOA, which indicates the presence
of an AB effect, was significant [F(2,56) 5 32.16, p ,
.001, d 5 2.14]. The critical relation between task and
SOA seems to be influenced by both modality and type of
sequence, as is suggested by the significant interactions
between modality, task, and SOA [F(2,56) 5 2.86, p 5
.04, d 5 0.64]; between task, SOA, and type of sequence
[F(6,168) 5 2.23, p 5 .02, d 5 0.56]; and between the
four factors [F(6,168) 5 1.91, p 5 .04, d 5 0.52].
To test the combined impact of modality and type of
sequence on the AB, the interaction between task and
SOA was analyzed for each of the four types of sequences
separately for each modality, using an alpha level of .01.
In the auditory condition, the task 3 SOA interaction was
significant at T1M1T2M [F(2,56) 5 5.30, p , .01, d 5
0.87], at T11T2M (F 5 8.83, p , .001, d 5 1.12), and
even at T1M1T2 (F 5 5.37, p , .01, d 5 0.88), but not
discrimination, with the onset of the mask (e.g., Massaro,
1973, 1975; see also Vachon & Tremblay, 2006). The addi-
tion of sensory noise to the target-relevant information by
integration masking may then have strongly reduced dis-
criminability (e.g., Kallman & Massaro, 1979; Massaro,
1975; see also Mattys, 1997). This hypothesis can account
for the notable impairment of the overall performance for
masked targets in the auditory modality. The next experi-
ment was designed to verify whether the results from Ex-
periment 1 are attributable to the fact that target syllables
were discriminated by their offset. If shifting the relevant
information away from the offset produced analogous AB
effects across modalities, it would strongly suggests that
perceptual affordances are responsible, at least to some
extent, for setting up attentional effects.
ExpEriMEnt 2
The paradigm and design employed in Experiment 2
were identical to those used in Experiment 1. However,
target syllables were discriminated henceforth by a varia-
tion located at their onset, rather than at their offset. A
number of studies showed that discrimination between
two consonants is easier when it takes place at the onset
of a consonant–vowel–consonant stimulus (e.g., Content,
Kearns, & Frauenfelder, 2001; Sidwell & Summerfield,
1986). In Experiment 2, the participants performed the
same discrimination task on the two targets; to do so, they
had to determine whether the target syllable began with
the letter m or the letter n. As in Experiment 1, two tar-
get syllables were employed: one syllable ending in ’ab
(either mab or nab) and another ending in ’ot (either mot
or not). Shifting the discriminating information from the
offset to the onset of the syllables should reduce the low-
level interference provided by the masks in the auditory
modality and, consequently, should facilitate identifica-
tion of auditory targets. Hence, the experimental setting
used in Experiment 2 should promote the appearance of a
T1 masking effect on the auditory AB. Given that the let-
ters forming the visual target syllables appeared simulta-
neously on the screen, this manipulation was not expected
to influence the pattern of results in the visual condition.
Method
The method was identical to that employed in Experiment 1, ex-
cept as noted below.
participants. Twenty-nine French-speaking adults who reported
having normal or corrected-to-normal vision and normal hearing
received a monetary compensation for their participation. None of
these participants had taken part in Experiment 1.
Apparatus and Stimuli. E-Prime 1.1 was used to run both the
auditory condition and the visual condition. A new set of target syl-
lables was employed: One target stimulus was an ’ab syllable (mab
or nab), and the other was an ’ot syllable (mot or not). The task per-
formed on each target item was identical, given that the participants
had always to discriminate between a syllable beginning with the
letter m and another beginning with the letter n.
results
As in Experiment 1, data in the single-task conditions
were pooled over target syllables (’ab and ’ot as single tar-

Page 9

1008 Vachon and treMBlay
inspection of Figure 5, showing AB effects only when T2
was masked.
Dual-task cost. In order to examine the impact of T1
masking on the AB in both the visual and the auditory
conditions, the dual-task cost was compared with respect
to SOA between an AB-inducing condition in which the
T1 mask was absent (T11T2M) and another in which the
T1 mask was present (T1M1T2M). To do so, a 2 3 3 re-
peated measures ANOVA with T1 mask and SOA as fac-
tors was carried out on the dual-task cost separately for
at T11T2 (F 5 1.31, p 5 .14, d 5 0.43). These results
reinforce the impression given by a visual inspection of
Figure 4 that an AB effect was observed in every audi-
tory condition except when both targets were unmasked.
In the visual condition, analyses revealed that the task 3
SOA interaction was significant at T1M1T2M (F 5
10.91, p , .001, d 5 1.25), approached significance at
T11T2M (F 5 3.54, p 5 .018, d 5 0.71), but was far
from significant at T1M1T2 and T11T2 (Fs , 1 and
ds , 0.26). These results are in agreement with a visual
0
50
60
70
80
90
100
% Correct
T1+T2 T1M+T2
–1,025–425 –275 275 4251,025
0
50
60
70
80
90
100
% Correct
SOA (msec)
T1+T2M
–1,025–425 –275275 4251,025
SOA (msec)
Single-task
Dual-task
T1M+T2M
Figure 4. results from the auditory condition in Experiment 2: Mean percentages of correct target responses as a function of task
(single vs. dual), t1–t2 stimulus onset asynchrony (SOA), and type of sequence (t1M1t2M, t11t2M, t1M1t2, and t11t2). posi-
tive SOAs refer to t2, and negative SOAs refer to t1. Error bars represent 95% within-subjects confidence intervals.

Page 10

Masking in the Visual and auditory aB 1009
significantly larger dual-task cost in the presence of a T1
mask at 275 msec [t(28) 5 3.55, p , .001, d 5 1.34] and
425 msec [t(28) 5 2.26, p 5 .02, d 5 0.85].
Discussion
As was expected, moving the discriminating informa-
tion from the offset to the onset of the target syllables did
not affect the pattern of results obtained in the visual con-
dition of the previous experiment: The visual AB emerged
exclusively when T2 was masked and was enlarged by the
each modality. In the auditory condition, the critical effect
of T1 mask was significant [F(1,28) 5 10.68, p , .01,
d 5 1.24], but the two-way interaction was not significant
[F(2,56) , 1, d 5 0.36]. When contrasted at each SOA,
the dual-task cost was significantly larger when T1 was
masked at 425 msec [t(28) 5 2.11, p 5 .02, d 5 0.55]. In
the visual condition, the ANOVA also showed a significant
effect of T1 mask [F(1,28) 5 28.79, p , .001, d 5 2.03],
with no significant two-way interaction [F(2,56) , 1,
d 5 0.35]. Analyses performed at each SOA revealed a
0
50
60
70
80
90
100
% Correct
T1+T2T1M+T2
–1,025–425 –275 275 4251,025
0
50
60
70
80
90
100
% Correct
SOA (msec)
T1+T2M
–1,025 –425 –275275 425 1,025
SOA (msec)
Single-task
Dual-task
T1M+T2M
Figure 5. results from the visual condition in Experiment 2: Mean percentages of correct target responses as a function of task
(single vs. dual), t1–t2 stimulus onset asynchrony (SOA), and type of sequence (t1M1t2M, t11t2M, t1M1t2, and t11t2). posi-
tive SOAs refer to t2, and negative SOAs refer to t1. Error bars are 95% within-subjects confidence intervals.

Page 11

1010 Vachon and treMBlay
sensitive to attentional manipulations (e.g., Content et al.,
2001; Mattys, 1997). Given that masking the T1 is said to
increase the attentional demand required to process T1 ef-
fectively (e.g., Chun & Potter, 1995; Seiffert & Di Lollo,
1997), it could be argued that the onset phoneme is par-
ticularly vulnerable to the interference from the remainder
of the stimulus when little or no attentional resources are
available. The presence of a larger AB deficit when T2 was
masked (i.e., in T1M1T2M) suggests that the deteriora-
tion of T2 onset would increase when a distinct auditory
event (i.e., a mask) follows the target within the sequence
(see also Vachon & Tremblay, 2006).
GEnErAl DiScuSSiOn
In the present study, the contribution of target mask-
ing to the AB phenomenon was compared between vision
and audition, using analogous verbal stimuli. The role of
masking was investigated by systematically manipulating
the presence of a trailing item after T1 and T2. In order to
isolate the impact of the masks from the interference en-
suing from the perceptual organization of a whole stream
of distractors, the stimulus sequences employed here con-
sisted of presenting the two targets and their respective
masks with no other distractor. Two experiments repli-
cated a key aspect of the AB phenomenon—namely, that
the occurrence of a masking item after T2 guarantees the
appearance of an AB effect in both vision (e.g., Giesbrecht
& Di Lollo, 1998) and audition (e.g., Vachon & Tremblay,
2005). Moreover, the present study provides evidence that
masking T1 modulates the expression of the AB not only
in the visual domain (e.g., Chun & Potter, 1995), but also
in the auditory domain. However, this effect of T1 mask-
ing on the auditory AB was noticeable when target syl-
lables varied at their onset (Experiment 2), but not when
they were discriminated by their offset (Experiment 1).
Although the failure to observe the impact of T1 mask-
ing in the auditory condition in Experiment 1 may have
ensued, at least in part, from floor effects, the fact remains
that, taken together, the results from the auditory condi-
tions in the two experiments highlighted the interaction
between masking interference and the temporal arrange-
ment of relevant information in audition.
Similarities and Discrepancies Between
the Visual and the Auditory AB
By comparing visual and auditory AB effects via a
within-subjects procedure similar in both modalities, the
present study clearly established the existence of func-
tional similarities between vision and audition with regard
to the role of masking interference in modulating the limi-
tations of the deployment of attention in time. Indeed, the
necessity of masking T2 to observe visual and auditory
AB effects indicates that for both vision and audition, the
role of T2 masking consists of deteriorating the percep-
tual representation of the target awaiting consolidation,
which thus prevents its conscious report (e.g., Giesbrecht
& Di Lollo, 1998; Jolicœur, 1999). Furthermore, by estab-
lishing masking of T1 as a way of influencing the expres-
sion of the auditory AB, our study suggests that, as in the
presentation of a masking item following T1. In the audi-
tory condition, introducing a mask after T2 also guaran-
teed that the AB would take place, as in Experiment 1.
The transformation of the target syllables induced some
changes in the results observed in the auditory condition.
First, backward masking did not lead to an important over-
all impairment in target identification, which diminishes
the likelihood of observing floor effects, and performance
was much less variable (see Figure 4). In fact, the detri-
mental effect of target masking on overall performance
was similar between the auditory and the visual condi-
tions. Such results were possibly the consequence of the
reduction of the low-level interference provided by audi-
tory integration masking and also the relative ease of dis-
criminating an auditory syllable by its onset, rather than
by its offset (e.g., Content et al., 2001; Sidwell & Sum-
merfield, 1986; Wingfield et al., 1997).
Experiment 2 also revealed a different pattern of results
concerning the impact of masking T1 on the auditory AB.
The magnitude of the T2 deficit in the auditory condi-
tion was larger when T1 was followed by a mask (i.e., for
T1M1T2M) than when the target was presented alone
(i.e., for T11T2M). This result is central because it dem-
onstrated for the first time that the influence of masking
T1 on the expression of the AB is not restricted to the
visual modality but extends also to the auditory modality,
providing new evidence of functional similarities between
the visual and the auditory AB. Therefore, it seems that in
the auditory as well as in the visual domain, T1 process-
ing can be impaired by the subsequent presentation of a
mask, which lengthens the postponement of T2 transfer
into STM (e.g., Chun & Potter, 1995; Jolicœur, 1998). The
finding that manipulating the presence of the T1 mask can
affect the expression of the auditory AB when the two tar-
gets were presented with no other stimuli than their re-
spective masks strongly suggests that the absence of such
an effect in Mondor’s studies (Mondor, 1998; Shen &
Mondor, 2006) was due to the overriding influence of the
perceptual organization of the whole sequence of distrac-
tors over that of the T1 mask.
The impact of the auditory masking of T1 within the
present experiment was not restricted to conditions in
which T2 was masked: A significant auditory AB effect
was found in the T1M1T2 condition—that is, when only
T1 was followed by a mask. Although the size of the AB
deficit was much smaller than that observed in the pres-
ence of a T2 mask, such a result may be taken to go against
the conclusion common to Experiment 1 and the study
of Vachon and Tremblay (2005), according to which T2
must be followed by a nontarget item for the auditory AB
to occur. The fact remains, nonetheless, that even in the
absence of a T2 mask, T2 ended with “nontarget” infor-
mation, since the discriminating information of T2 was
located at the onset of the target item. Hence, the auditory
AB obtained in the T1M1T2 condition could have been
the consequence of backward interference exerted by the
offset of T2 on its onset. The occurrence of such a time-
locked deficit in the absence of an item after T2 was re-
stricted to the condition in which T1 was masked. There is
evidence suggesting that onset processing is particularly

Page 12

Masking in the Visual and auditory aB 1011
temporal processing limitations (e.g., Kellie & Shapiro,
2004; Raymond, 2003).
At first blush, the influence of T1 masking on the AB
deficit appears to vary according to the modality of pre-
sentation: Whereas such an effect is robust in the visual
domain (see Visser, 2007), it is not systematically ob-
served in the auditory domain. In effect, the impact of
masking T1 on the auditory AB seems rather sensitive
to the experimental context, since the removal of the T1
mask had no effect when spoken syllables were discrimi-
nated by their offset (Experiment 1 of the present study)
or when targets were embedded in a sequence of distractor
tones (Mondor, 1998; Shen & Mondor, 2006). Although
floor effects may have obscured the potential effects of T1
masking in Experiment 1, such a factor cannot account for
Mondor’s results.
One way to reconcile Mondor’s (1998; Shen & Mon-
dor, 2006) findings with the results in the visual AB lit-
erature is to refer to the special role played by perceptual
organization in rapid auditory sequences. In both vision
and audition, a perceptual process acts preattentively
to integrate and group incoming stimuli on the basis of
their environmental origin. Besides, the dynamics of per-
ceptual grouping of visual and auditory information are
based on the same Gestalt principles of similarity and
proximity (see Aksentijević, Elliott, & Barber, 2001, for a
discussion). Despite these similarities in perceptual orga-
nization between the two domains, information grouping
operates mainly from the spatial dimension in vision and
from the temporal and the spectral dimensions in audition
(e.g., Aksentijević et al., 2001; Bregman, 1990; Koffka,
1935). This divergence across modalities is particularly
consequential when one considers the paradigm to be em-
ployed to study the AB. Indeed, within a visual sequence,
sensory information typically varies in time but not in
space, which reduces the likelihood that visual stimuli
will be grouped. Although the temporal dimension can
contribute to perceptual organization in vision (e.g.,
Bregman & Achim, 1973), it plays a more important role
in audition because of the sequential nature inherent in an
auditory stimulation. Within the experimental context of
the auditory AB, stimuli change rapidly not only in time,
but also in frequency, promoting the action of percep-
tual organization processes (e.g., Beauvois, 1998; Breg-
man, Ahad, Crum, & O’Reilly, 2000; Macken, Tremblay,
Houghton, Nicholls, & Jones, 2003). Furthermore, there
is evidence that perception of an auditory stimulus within
a sequence depends to a great extent on the context in
which it is embedded (e.g., Brochard, Drake, Botte, &
McAdams, 1999; Johnston & Jones, 2006; Nicholls &
Jones, 2002), illustrating the superiority of the sequence
over the item in audition. Therefore, given the higher
propensity of auditory stimuli, as compared with visual
stimuli, to be perceptually grouped in rapid sequences, it
is possible that in the auditory sequences used by Mondor
(1998; Shen & Mondor, 2006), distractors, including the
T1 mask, were designated members of the same percep-
tual stream by virtue of their similarity—they were all
pure tones—and were then inhibited as a group, render-
ing the interference provided by T1 mask ineffective in
visual modality (e.g., Seiffert & Di Lollo, 1997), auditory
masking may slow down the processing of an auditory
target, so that it yields a longer delay in the processing of
a subsequent target stimulus. The present findings provide
further evidence that, in contrast with previous claims
(see, e.g., Chun & Potter, 2001), auditory information is as
sensitive as its visual counterpart to the interference from
subsequent stimulations (Shen & Mondor, 2006; Vachon
& Tremblay, 2005, 2006).
The comparable role played by target masking in the vi-
sual and the auditory AB highlighted in the present study
suggests that the temporal deployment of attention is con-
trolled by mechanisms common to every sensory modality
that are probably central in nature (e.g., Arnell & Jenkins,
2004; Arnell & Jolicœur, 1999; Jolicœur & Dell’Acqua,
1998).2 There are also a number of studies in the AB lit-
erature that provide evidence of similarities between vi-
sual AB and auditory AB phenomena. For instance, het-
erogeneous distractors tend to produce a greater AB than
do homogeneous distractors, whether in visual (Ross &
Jolicœur, 1996, reported in Arnell & Jolicœur, 1999) or in
auditory (Tremblay, Vachon, & Jones, 2005) sequences.
Moreover, Arnell and Jenkins extended to the auditory do-
main the modulating effect that similarity between T2 and
its surrounding distractors exerted on the visual AB (e.g.,
Maki, Bussard, Lopez, & Digby, 2003). This accumulat-
ing evidence of functional equivalence between the visual
and the auditory AB leads us to conclude that the phe-
nomenon reflects a fundamental limit of human cognition.
Such a conclusion is in line with the central interference
theory (e.g., Arnell & Jolicœur, 1999; Jolicœur, 1998,
1999; Jolicœur & Dell’Acqua, 1998), according to which
the AB originates from a central bottleneck that is amodal
in nature. Given that this theory was developed within the
bottleneck framework, which generally provides the best
account for the effects of masking on the AB (see Kawa-
hara, Enns, & Di Lollo, 2006), it appears to be particularly
suitable for the present findings.
The present study revealed not only similarities but also
discrepancies between the visual and the auditory AB.
Probably the most striking divergence between the two
phenomena was related to the sensitivity to the temporal
arrangement of relevant information. Indeed, the results
from the two present experiments showed that whether
the discriminating information is located at the beginning
or at the end of a target syllable can modulate the expres-
sion of the AB in audition, whereas it has no particular
effect in vision. This difference between the two modali-
ties appears to ensue from a fundamental distinction in
perceptual processing between vision and audition. Ac-
cording to several authors (e.g., Cusack & Carlyon, 2003;
Kubovy & Van Valkenburg, 2001; Mondor & Terrio,
1998; Näätänen & Winkler, 1999), the formation of vi-
sual objects is based mainly on the integration of features
in space (see also Treisman & Gelade, 1980), whereas in
audition, the mediums of object formation are time and
frequency. So, a change in the temporal nature of stimuli
should affect only processes involved in the formation of
auditory representations. The present findings indicate
that the way perceptual objects are formed may modulate

Page 13

1012 Vachon and treMBlay
In an attempt to refine the mechanisms responsible
for modality-specific and amodal limitations in temporal
information processing, we set the multiple-sources-of-
interference approach of Arnell and Duncan (2002) within
the bottleneck framework of the central interference
theory (Jolicœur, 1998; Jolicœur & Dell’Acqua, 1998).
According to this theory, information presented within
a stimulus sequence goes through two stages of process-
ing: (1) a first stage of formation and selection of percep-
tual representations and (2) a second stage during which
selected representations are consolidated into STM. We
suppose that within-modality constraints restrict process-
ing at the first stage, whereas, as is assumed by the central
interference theory, a central bottleneck is responsible for
limitations at the second stage of processing. The theoreti-
cal approach described here is illustrated in Figure 6.
During the first stage, information from the stimulus se-
quence is extracted and then integrated so as to create per-
ceptual representations that must be selected in order to be
consolidated in STM (e.g., Chun & Potter, 1995; Jolicœur
& Dell’Acqua, 1998). There is recent evidence suggest-
ing that constraints in the selection of information play an
important role in the AB (e.g., Nieuwenstein, 2006; Nieu-
wenstein, Chun, van der Lubbe, & Hooge, 2005; Olivers
& Watson, 2006). As initially put forward by Potter, Staub,
and O’Connor (2002), we assume that stimuli compete for
attention in order to be identified and then are selected for
further processing. The level of competition for selection
is, at least in part, determined by the presence of perceptual
interference from irrelevant stimuli, especially that ensu-
ing from similarity with the target stimuli, and by target
structural descriptions (e.g., Duncan & Humphreys, 1989;
Mondor & Terrio, 1998). As a consequence, the result of
the competition relies on the product of object formation
and perceptual organization, which, as was mentioned ear-
lier, appear to differ at some point according to the modal-
ity. Thus, differences between the visual and the auditory
AB are likely to come up from the first stage of process-
ing. Unlike Arnell and Duncan (2002), who suggested that
modality-specific limitations arise because “to some ex-
tent at least, different perceptual resources are required for
processing in visual and auditory modalities” (p. 142), we
ascribe such limits instead to the selection process, which
is constrained by the way representation formation and or-
ganization processes operate.
Because representations at the first stage are sensitive
to perceptual interference and cannot serve as a basis for
response, they must be transformed into a more durable
form for a subsequent report (e.g., Chun & Potter, 1995;
Jolicœur & Dell’Acqua, 1998). Selection of a potential
target initiates a second stage of processing in which the
representation is consolidated into STM. Short-term con-
solidation is assumed to require central bottleneck pro-
cessing (e.g., Jolicœur & Dell’Acqua, 1998). So, during
consolidation of T1, operations necessitating the partici-
pation of central mechanisms, such as short-term consoli-
dation of T2 or response selection (e.g., Arnell & Duncan,
2002; Jolicœur, 1999), must wait. When T2 is selected
before the end of T1 consolidation, its transfer in STM
is temporarily suspended and its representation is de-
affecting the auditory AB. When the influence of percep-
tual organization is minimized—for example, by remov-
ing all distractors (except the masks) from the sequence,
as we did in the present research—the interference com-
ing from the T1 mask can have an effect on the magnitude
of the auditory AB (see Experiment 2).
The hypothesis according to which central and amodal
attentional limitations are responsible for the AB does not
seem to chime harmoniously with the differences high-
lighted in the present study between the visual and the
auditory AB. Other variations in the manifestation of vi-
sual and auditory AB patterns have been reported in the
literature. For example, the auditory AB rarely appeared
U-shaped (Soto-Faraco & Spence, 2002; Tremblay et al.,
2005), as opposed to the visual AB (see Visser, Bischof, &
Di Lollo, 1999). One way to account at once for the simi-
larities and discrepancies existing between the visual and
the auditory AB is to posit that the phenomena ensue from
mechanisms specific to each modality (e.g., Hein, Parr, &
Duncan, 2006; Soto-Faraco & Spence, 2002), but working
in a similar fashion. However, the idea that distinct mod-
ules are performing the same operations in the same way
is not the most parsimonious. Moreover, this approach
has no provision that would account for the existence of
cross-modal AB effects—that is, T2 deficits occurring
when the two targets are presented in different modalities
(e.g., Arnell & Jolicœur, 1999; Arnell & Larson, 2002;
Soto-Faraco et al., 2002). Nevertheless, the notion that
constraints specific to each sensory system are respon-
sible for the AB is not necessarily incompatible with the
concept of central bottleneck processing limitations.
Multiple Sources of interference
in Human information processing
One promising way to consider the AB as a phenom-
enon sensitive to amodal, as well as to modality-specific,
factors is to apply the multiple-sources-of-dual-task-cost
approach put forward by Arnell and Duncan (2002; see
also Arnell, 2001; Arnell & Jenkins, 2004). According to
these authors, temporal processing in dual tasking is lim-
ited by both central and within-modality constraints. Such
an account not only provides an answer for the existence of
auditory and cross-modal ABs, but also explains why AB
deficits are larger and more robust within than between
modalities (e.g., Arnell & Jenkins, 2004; Arnell & Larson,
2002). Indeed, it is suggested that when the two targets are
presented in the same modality, two sources of interference
contribute to the T2 deficit: one source that is specific to
the modality of presentation and another that is central and
amodal. On the other hand, cross-modal AB effects are ex-
clusively the consequence of central limitations. A similar
view was proposed by Chun and Potter (2001; Potter et al.,
1998), in which the visual AB reflects limits of visual-
processing capacity accentuated by a central bottleneck,
whereas the origin of T2 deficits in audition is restricted
to the latter source of interference. However, the results
from the present study showed that factors affecting only
auditory information processing can modulate the auditory
AB, suggesting that the phenomenon is also sensitive to
modality-specific constraints, as in vision.

Page 14

Masking in the Visual and auditory aB 1013
patterns of AB when perceptual parameters are tuned to
equate affordances across modalities.
AutHOr nOtE
This study was presented at the 12th Meeting of the Cognitive Science
Association for Interdisciplinary Learning in August 2006, Hood River,
Oregon. This work was supported by a grant from the Fonds québécois
pour la recherche sur la nature et les technologies to S.T. F.V. received
support from the Natural Sciences and Engineering Research Council
of Canada in the form of a doctoral scholarship. We are grateful to Na-
dine Hamel and Sonia Packwood for running the experiments and to
Richard Lapointe-Goupil for his technical assistance. Correspondence
concerning this article should be addressed to F. Vachon, Département de
psychologie, Université de Montréal, C.P. 6128, Succursale Centre-ville,
Montreal, QC, H3C 3J7 Canada (e-mail: f.vachon@umontreal.ca).
rEFErEncES
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Object Formation and Perceptual Organization
Spatial integration
Object Selection
Competition
Visual Modality
Object Formation and Perceptual Organization
Temporal and spectral integration
Object Selection
Competition
Auditory Modality
Short-Term Consolidation
Response Selection
Central Bottleneck
Stage 1 Stage 2
Figure 6. illustration of the multiple-sources-of-interference approach applied to the central
interference theory (e.g., Jolicœur, 1998; Jolicœur & Dell’Acqua, 1998). temporal information
processing is first limited by the selection process (Stage 1), which is delineated by the properties of
object formation and perceptual organization that are specific to each sensory modality, and then
by an amodal bottleneck for operations requiring central processing (Stage 2), such as short-term
consolidation and response selection.

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