The representation of meaning is a pivotal topic for theories of language processing.
A prevalent view is based on semantic features, considering conceptual representations
as distributed patterns of activity across sets of features related to different aspects
of knowledge and experience (e.g., Rosch and Mervis, 1975; Vigliocco et al., 2004;
Cree et al., 2006). These features can vary in their relative salience to a concept's
meaning and co-occur to various degrees across concepts. For example, distinctive
features occur in few concepts and allow people to distinguish very similar concepts
(Grondin et al., 2009), while shared features occur across many concepts thus indicating
similarity among them (Montefinese et al., 2014a). Existing studies yield conflicting
results about the relevance of featural characteristics (Montefinese et al., 2014b),
leaving it unclear what theoretical interpretations can be drawn.
Vieth et al. (2014) recently sought to clarify the role of feature distinctiveness
in a picture-word interference (PWI) task. In Experiment 1, they employed categorically-related
distractor-target pairs matched for semantic similarity, while manipulating distinctiveness
of the distractor feature. Experiments 2 and 3 employed part-whole distractor pairs
while manipulating distinctiveness and visibility of the distractor feature in the
target picture. Distinctiveness had an extremely constrained effect: non-distinctive
feature distractors slowed target naming, but only at an SOA of −150 ms and only when
they were visible in the picture (Experiment 3). The authors conclude that semantic
interference in the PWI paradigm is due to conceptual feature overlap and thus consistent
with lexical selection by competition (Roelofs, 1992) rather than the response exclusion
hypothesis introduced by Mahon et al. (2007). Unfortunately, these conclusions are
undermined by lack of a crucial statistical interaction to motivate follow-up testing,
poor control of semantic measures, and an inadequate account of the role distinctiveness
would play in lexical retrieval.
Vieth et al. found one effect of distinctiveness: in Experiment 3, “non-distinctive
part-whole target relations showed picture naming latencies significantly at −150
ms SOA compared to their matched unrelated pairings” (p. 9). However, such conclusions
are not warranted by the evidence provided. The authors drew conclusions from partial
interactions without a significant higher-order interaction. However, this is a common
problem in studies employing factorial ANOVA (see Nieuwenhuis et al., 2011), and is
likely to inflate the likelihood of Type I error particularly in repeated-measures
ANOVA, which is anticonservative for designs including crossed random effects by-participants
and by-items (Quené and van den Bergh, 2008). We therefore wonder whether the most
appropriate conclusion from Experiment 3 is that, as in Experiments 1 and 2, feature
distinctiveness does not affect the degree of interference in PWI.
Moreover, although the authors made careful efforts to match lexical variables between
conditions, some crucial semantic variables remain uncontrolled. For example, there
are substantial differences in dominance of the distinctive and non-distinctive features
Vieth et al. used in their experiments. Moreover, hardly any of the non-distinctive
features appear in McRae et al.'s (2005) norms (Table 1), indicating that participants
do not find features like “knees” of CAMELS sufficiently salient to report them. Classic
feature-verification studies using very similar item sets (e.g., Conrad, 1972; Glass
et al., 1974) suggest that distinctiveness effects are substantially reduced or eliminated
by taking dominance into account; and more recent work by O'Connor et al. (2009) suggests
that non-distinctive features are much more highly associated with superordinate terms
(e.g., “animal” or “mammal”) than the basic-level terms employed by Vieth et al. Therefore,
if dominance is a measure of a feature's semantic proximity to the target concept
label (and thus its level of competition for lexical selection under selection-by-competition
accounts), the activation of target concepts by non-distinctive features would depend
on their dominance. Features that are salient for multiple concepts would activate
competing concepts and interfere with their naming, while those that are not salient
for any concept would not. Examples of these two types of non-distinctive features
are, respectively, “bone” and “skin,” which were listed for none and 16 of the 541
concepts of McRae et al.'s norms. In brief, distinctiveness alone would not explain
how strongly a feature can activate one or more target concepts. But let us set aside
statistical and methodological concerns about Experiment 3 and assume that the effect
they describe is real interference for visible non-distinctive part distractors at
−150 ms SOA only. The authors do not adequately describe the processes that might
have caused this temporally-selective effect, instead discussing the three-way interaction
(SOA × part-relation × distinctiveness) as if it was the two-way interaction (part-relation
× distinctiveness, which is far from statistical significance). Moreover, the proposed
mechanism by which this effect would occur under selection-by-competition is discussed
as spreading activation from a target concept to a related distractor (a visible,
non-distinctive feature in this case). If this is the mechanism underlying this effect,
one should expect no difference between −150 ms and 0 ms SOA: activation of target
concept cannot begin before it has appeared. If anything, spread of activation in
the other direction [i.e., from feature to its associated concept(s)] should initially
drive this effect at −150 ms SOA. And finally, if this effect occurs only when the
feature is visible (for counter evidence, see Sailor and Brooks, 2014), we wondered
whether there may be a contribution of level of specificity (akin to the basic-level/superordinate
naming tasks reviewed by Mahon et al., 2007): might the visibility of the distractor
feature permit further activation of its name as a potentially plausible alternative
to the basic-level target name?
Table 1
Materials from Vieth et al. (2014) Experiment 2 and 3.
Distinctive
Non-distinctive (Exp2)
Non-distinctive (Exp3)
Target picture
Feature
Dominance
Feature
Dominance
Feature
Dominance
BAT
Fangs
7
Stomach
NA
BED
Springs
7
Foam
NA
a
BRA
Hook
9
Cloth
5
CAMEL
Hump
25
Knee
NA
CHURCH
Altar
8
Seat
11
CLOCK
Face
7
Spindle
NA
b
Glass
NA
d
COTTAGE
Fireplace
6
Floor
NA
COW
Udder
8
Liver
NA
Skin
NA
CROCODILE
Jaws
7
Heart
NA
Scales
8
DISHWASHER
Rack
13
Hose
NA
Latch
NA
DUCK
Bill
14
Eye
NA
ELEPHANT
Trunk
23
Teeth
NA
c
Toe
NA
ELEVATOR
Cable
9
Ceiling
NA
GOAT
Beard
14
Tail
6
GRENADE
Pin
23
Lever
NA
GUITAR
Hole
8
Fret
NA
LAMP
Switch
10
Cord
5
MISSILE
Warhead
6
Engine
NA
Fin
NA
MIXER
Bowl
5
Plug
NA
MOUSE
Ball
9
Sensor
NA
Button
9
PEACH
Stone
6
Stem
NA
PIG
Snout
12
Tongue
NA
Hair
NA
PINEAPPLE
Core
6
Stone
NA
Leaf
7
VULTURE
Talons
6
Bone
NA
Wings
8
The two rightmost columns indicate the non-distinctive features used in Experiment
3 only when they differed from those used in Experiment 2. “NA”: a feature did not
appear in McRae et al. (2005) norms, and thus had a dominance of 4 or less in that
set.
a
Most similar feature in McRae et al.'s norms: “has a mattress” (dominance = 18).
b
Most similar feature in McRae et al.'s norms: “has hands” (dominance = 18).
c
Most similar feature in McRae et al.'s norms: “has tusks” (dominance = 14).
d
Most similar feature in McRae et al.'s norms: “has a face” (dominance = 7).
Although we appreciate Vieth et al.'s effort to advance our theoretical understanding
of lexical retrieval processes through careful manipulation of feature properties,
we cannot draw conclusions about the locus of semantic effects in PWI from the present
study. Ultimately, a crucial problem is that the details of conceptual representation
remain underspecified, and may have major consequences, for example, in predicting
whether a feature label should compete with a basic level label (see Vinson et al.,
2014). Incorporating explicit models of semantic similarity may offer a way forward
in testing current theories of lexical retrieval.
Conflict of interest statement
The authors declare that the research was conducted in the absence of any commercial
or financial relationships that could be construed as a potential conflict of interest.