Lexical Retrieval is not by Competition: Evidence from the Blocked Naming Paradigm

Abstract

A central issue in research on speech production is whether or not the retrieval of words from the mental lexicon is a competitive process. An important experimental paradigm to study the dynamics of lexical retrieval is the blocked naming paradigm, in which participants name pictures of objects that are grouped by semantic category ('homogenous' or 'related' blocks) or not grouped by semantic category ('heterogeneous' or 'unrelated' blocks). Typically, pictures are repeated multiple times (or cycles) within both related and unrelated blocks. It is known that participants are slower in related than in unrelated blocks when the data are collapsed over all within-block repetitions. This semantic interference effect, as observed in the blocked naming task, is the strongest empirical evidence for the hypothesis of lexical selection by competition. Here we show, contrary to the accepted view, that the default polarity of semantic context effects in the blocked naming paradigm is facilitation, rather than interference. In a series of experiments we find that interference arises only when items repeat within a block, and only because of that repetition: What looks to be 'semantic interference' in the blocked naming paradigm is actually less repetition priming in related compared to unrelated blocks. These data undermine the theory of lexical selection by competition and indicate a model in which the most highly activated word is retrieved, regardless of the activation levels of nontarget words. We conclude that the theory of lexical selection by competition, and by extension the important psycholinguistic models based on that assumption, are no longer viable, and frame a new way to approach the question of how words are retrieved in spoken language production.

Keywords: blocked naming; cyclic naming; lexical retrieval; semantic facilitation; semantic interference; speech production.

Figure 1

Reanalysis of the data from Experiment 2 in Navarrete and colleagues (2012). The black and grey bars show actual data, indicating that i) there is semantic facilitation in the first cycle, and that it is, if anything, greater for semantically more close (within-category) than semantically more distant (within-category) blocks, and ii) there is semantic interference for the second cycle, and it is, if anything, greater for semantically more similar (within-category) than semantically more distant (within-category) blocks. As a demonstration of principle, we then computed hypothetical cycle 2 data by reducing cycle 1 response times by a proportionally equivalent amount (15%). As can be seen, if there were proportionally equivalent repetition priming for all contexts, then semantic interference would not emerge in cycle 2. This suggests that the emergence of semantic interference may derive from a baseline shift in the unrelated condition. In other words, the emergence of semantic interference depends (by hypothesis) on greater repetition priming in the unrelated than the related conditions.

Figure 2

Schematic of the experimental design used in Experiment 1. Blue and red lines represent (some of) the picture items, split into A and B sets for counterbalancing the design across participants. The shaded background behind the lines indicates the type of context (related or unrelated). The innovation of this design is that i) all items are presented in an unrelated context for the first two times that participants see (and name) the items, and then ii) half of the categories are presented in related contexts and the other half in unrelated contexts beginning at presentation 3 (counterbalanced across participants), and iii) each item is presented only once in each block. This design allows us to test whether related (i.e., homogenous) contexts lead to interference, as predicted by lexical selection by competition, or to facilitation, as predicted by noncompetitive models, while removing the (potentially) confounding factor of ’within block repetition’.

Figure 3

Response time effects in Experiment 1. A. Mean naming latencies by Semantic Context and Presentation for Experiment 1. As can be seen, semantic facilitation is preserved through to presentation 6. B. Semantic facilitation increases with ordinal position within block. Semantic facilitation effects are calculated as Related minus Unrelated, for each corresponding ordinal position within-block. All error bars are standard error of the mean.

Figure 4

Schematic of the experimental design used in Experiment 2b. In this experiment, the same design as in Experiments 1 and 2a was used, with the difference that presentations 7/8/9 were collapsed into a single block as were presentations 10/11/12. This ‘cross over’ design allows us to test whether the emergence of ‘interference’ depends on repetition within block (i.e., presentations 7/8/9), and whether once interference emerges, it is preserved for all subsequent presentations of that context in the experiment (i.e., presentation 10), or rather reverts to facilitation at the first presentation within-block (i.e., presentation 10).

Figure 5

Response time effects in Experiment 2. A. Mean naming latencies by Semantic Context and Cycle for Experiment 2a. As can be seen, semantic facilitation is preserved through to presentation 12. B. Mean naming latencies by Semantic Context and Cycle for Experiment 2b. As can be seen, the emergence of semantic interference depends on items repeating within blocks. C, D. Magnitude of the contextual semantic effect (Related minus Unrelated) by Ordinal position within-block for Experiment 2a (collapsing across presentations 3 to 12) and 2b (collapsing across presentations 3 to 6).

Figure 6

Demonstration that a baseline shift in the unrelated condition due to differential repetition priming in that condition is the basis for the emergence of ‘semantic interference.’ The data from Experiment 2b were reduced to a 2×2 design of Semantic Context (Related/Unrelated) and Cycle (i.e., within-block presentation; First/Second). The data from presentations 7 and 10 were combined into the ‘First Cycle’ data points, and presentations 8 and 11 into the ‘Second Cycle’ data points, separately for the related and unrelated conditions. The results of this analysis show that the emergence of ‘semantic interference’ with within-block repetition is caused by differential repetition priming in the unrelated compared to the related condition.

Figure 7

Response times by ordinal position within category for related and unrelated contexts. The data from all experiments (1, 2a and 2b) were combined for presentations 3 through 6 (as the design of all experiments was identical through presentation 6). A. The graph shows mean naming latencies by ordinal position within category, separately for related and unrelated contexts (error bars correspond to standard errors of the means, over subjects). The analysis for the unrelated condition is by definition across blocks, while the analysis for the related condition is by definition a within-block analysis (i.e., ordinal position within category and ordinal position within block in the related condition are one and the same thing). As can be seen, there is a progressive slowing of response times in the unrelated condition with ordinal position within category, but a progressive decrease in response times in the related condition. B. The data comprising the two lines plotted in Panel A are now plotted against each other. The tight relationship suggests that semantic priming and incremental weakening are mirror image phenomena in that they both serve as barometers of the same underlying distributions of activation levels at the lexical level.