Phrase length matters: the interplay between implicit prosody and syntax in Korean "garden path" sentences

In spoken language comprehension, syntactic parsing decisions interact with prosodic phrasing, which is directly affected by phrase length. Here we used ERPs to examine whether a similar effect holds for the on-line processing of written sentences during silent reading, as suggested by theories of "implicit prosody." Ambiguous Korean sentence beginnings with two distinct interpretations were manipulated by increasing the length of sentence-initial subject noun phrases (NPs). As expected, only long NPs triggered an additional prosodic boundary reflected by a closure positive shift (CPS) in ERPs. When sentence materials further downstream disambiguated the initially dispreferred interpretation, the resulting P600 component reflecting processing difficulties ("garden path" effects) was smaller in amplitude for sentences with long NPs. Interestingly, additional prosodic revisions required only for the short subject disambiguated condition-the delayed insertion of an implicit prosodic boundary after the subject NP-were reflected by a frontal P600-like positivity, which may be interpreted in terms of a delayed CPS brain response. These data suggest that the subvocally generated prosodic boundary after the long subject NP facilitated the recovery from a garden path, thus primarily supporting one of two competing theoretical frameworks on implicit prosody. Our results underline the prosodic nature of the cognitive processes underlying phrase length effects and contribute cross-linguistic evidence regarding the on-line use of implicit prosody for parsing decisions in silent reading.     

An ERP study of syntactic processing in English and nonsense sentences

The timecourse of the interaction between syntactic and semantic information during sentence processing in monolingual native English speakers was investigated using event-related potentials (ERPs). To examine the effects of semantic information on syntactic processing, the results for normal English sentences were compared to those for semantically impoverished nonsense (Jabberwocky) sentences. Within each sentence type condition, half of the sentences contained a syntactic violation. Violations elicited a larger amplitude N1 and more negative ERPs around 200 ms after the onset of the critical word relative to the grammatical condition. Although these effects were observed in both sentence types, they were anteriorly distributed for English sentences only. Moreover, the P600 elicited by the syntactic violation was attenuated in processing Jabberwocky as compared to English sentences. These results suggest that semantic and syntactic information are integrated during the earlier stages of syntactic processing indexed by the anterior negativities, and that these interactions continue in the later stages of processing indexed by the P600.     

Pitch modulates lexical identification in spoken word recognition: ERP and behavioral evidence

Event-related potentials (ERPs) were recorded in cross-modal word fragment priming (CMWP) to address the function of pitch for the identification of spoken words. In CMWP fragments of spoken words (e.g., re taken from Regal [Engl. shelves]) are immediately followed by visual targets. Together with reduced reaction times (RTs), an ERP deflection named P350 has been found to be reduced for targets, which match the primes (e.g., in the prime-target pair re-REGAL) as compared to unrelated targets (e.g., re-WIRBEL [Engl. burble]). The P350 has been related to facilitated lexical identification [Friedrich, Kotz, Friederici and Gunter (in press), ERPs reflect lexical identification in word fragment priming, JOCN]. In the present study, we presented syllable primes with different pitch contours. One version of each prime bore a stressed pitch contour (e.g., re_1), the other an unstressed pitch contour (e.g., re_2). Primes were combined with targets being either stressed on the first syllable (e.g., REgel [Engl. rule]) or on the second syllable (e.g., reGAL [Engl. shelves]). We found a reduced amplitude of the P350 and slightly faster reactions for targets with a stress pattern that matched the pitch of the primes (e.g., re_1-REgel) as compared to targets with a stress pattern that did not match the pitch of the primes (e.g., re_1-reGAL). The present study replicates the P350 effect with different material, and indicates that pitch is used for lexical identification in spoken word recognition.     

Repetition suppression for spoken sentences and the effect of task demands

We examined whether the repeated processing of spoken sentences is accompanied by reduced bold oxygenation level-dependent response (repetition suppression) in regions implicated in sentence comprehension and whether the magnitude of such suppression depends on the task under which the sentences are comprehended or on the complexity of the sentences. We found that sentence repetition was associated with repetition suppression in temporal regions, independent of whether participants judged the sensibility of the statements or listened to the statements passively. In contrast, repetition suppression in inferior frontal regions was found only in the context of the task demanding active judgment. These results suggest that repetition suppression in temporal regions reflects facilitation of sentence comprehension processing per se, whereas in frontal regions it reflects, at least in part, easier execution of specific psycholinguistic judgments.     

Influence of prosodic information on the processing of split particles: ERP evidence from spoken German

Spoken language comprehension involves the use of different sources of linguistic information such as prosodic, syntactic, lexical, and semantic information. The question, however, of 'when' and 'how' these sources of information are exploited by the language processing system still remains unanswered. In the present study, we used event-related brain potentials (ERPs) to investigate the interaction between prosodic, syntactic, and lexical information during the processing of spoken German sentences. The sentence structure was manipulated by positioning a split particle at the end of the sentences after the occurrence of inflected verb whose lexical entry does not contain a split particle (e.g., *Sie alarmierte den Detektiv an [*She alerted at the detective]) [According to linguistic convention, incorrect sentences are marked by an asterisk.]. The prosodic contour of the verb stems was manipulated such that it marked either the presence of a split particle at a later position in the sentence or not. Participants performed an off-line probe-detection task. ERP data indicate that prosodic information of German-inflected verb stems is consulted on-line by the language processing system ('parser') in order to 'predict' the presence of a split particle at a later position in the sentence. An N400 effect was observed for the processing of split particles following verb stems which do not take a particle. However, this effect was only observed when the prosody of the verb stem did signal the presence of a split particle. We argue that the N400 component reflects the high costs associated with the lexical search that the language processing system has to perform when confronted with nonexisting words such as these resulting from the combination of the split particle and the verb stem in the present study. Furthermore, as a general reflection of prosodic processes, a Closure Positive Shift (CPS) was found at intonational phrase boundaries. In sum, the present findings provide strong evidence that prosodic information is a good 'predictor' of upcoming information during the auditory processing of German sentences.     

ERP effects of listening to speech compared to reading: the P600/SPS to syntactic violations in spoken sentences and rapid serial visual presentation

In this study, event-related brain potential effects of speech processing are obtained and compared to similar effects in sentence reading. In two experiments sentences were presented that contained three different types of grammatical violations. In one experiment sentences were presented word by word at a rate of four words per second. The grammatical violations elicited a Syntactic Positive Shift (P600/SPS), 500 ms after the onset of the word that rendered the sentence ungrammatical. The P600/SPS consisted of two phases, an early phase with a relatively equal anterior-posterior distribution and a later phase with a strong posterior distribution. We interpret the first phase as an indication of structural integration complexity, and the second phase as an indication of failing parsing operations and/or an attempt at reanalysis. In the second experiment the same syntactic violations were presented in sentences spoken at a normal rate and with normal intonation. These violations elicited a P600/SPS with the same onset as was observed for the reading of these sentences. In addition two of the three violations showed a preceding frontal negativity, most clearly over the left hemisphere.     

Perception of the prosody and content of sentences in an unfamiliar language in children with autism spectrum disorders

Prior research suggests that children with autism spectrum disorders (ASD) show atypical patterns of attention to the prosody (intonation and emotional tone of voice) and content (words) of spoken sentences. Using a discrimination-choice procedure embedded in a custom-made videogame, we examined attention to these features of sentences in 15 children with ASD (ages 5 years, 5 months–18 years) and 15 age-matched typical controls (TYP). Using an unfamiliar language (German) to remove semantics, we assessed the role of meaning in promoting attention to content over prosody. As in a previous study with English sentences, TYP children attended to content to a greater extent than children with ASD while maintaining equivalent levels of discrimination based on prosody. However, in contrast to previous results, TYP children did not show a preference for enthusiastic over grouchy tone of voice, which suggests that the unfamiliar language rendered affective valence less salient. The results confirm intact perception of prosody in children with ASD, and a more selective pattern of attention to content in TYP children.     

Semantic integration in sentences and discourse: evidence from the N400

In two ERP experiments we investigated how and when the language comprehension system relates an incoming word to semantic representations of an unfolding local sentence and a wider discourse. In Experiment 1, subjects were presented with short stories. The last sentence of these stories occasionally contained a critical word that, although acceptable in the local sentence context, was semantically anomalous with respect to the wider discourse (e.g., Jane told the brother that he was exceptionally slow in a discourse context where he had in fact been very quick). Relative to coherent control words (e.g., quick), these discourse-dependent semantic anomalies elicited a large N400 effect that began at about 200 to 250 msec after word onset. In Experiment 2, the same sentences were presented without their original story context. Although the words that had previously been anomalous in discourse still elicited a slightly larger average N400 than the coherent words, the resulting N400 effect was much reduced, showing that the large effect observed in stories depended on the wider discourse. In the same experiment, single sentences that contained a clear local semantic anomaly elicited a standard sentence-dependent N400 effect (e.g., Kutas &Hillyard, 1980). The N400 effects elicited in discourse and in single sentences had the same time course, overall morphology, and scalp distribution. We argue that these findings are most compatible with models of language processing in which there is no fundamental distinction between the integration of a word in its local (sentence-level) and its global (discourse-level) semantic context.     

It's early: event-related potential evidence for initial interaction of syntax and prosody in speech comprehension

Psycholinguistic theories assume an interaction between prosody and syntax during language processing. Based on studies using mostly off-line methods, it is unclear whether an interaction occurs at later or initial processing stages. Using event-related potentials, the present study provides neurophysiological evidence for a prosody and syntax interaction in initial processing. The sentence material contained mere prosodic and syntactic as well as combined prosodic-syntactic violations. For the syntax violation, the critical word appeared after a preposition. The suffix of the critical word either indicated a noun fulfilling the syntactic requirements of the preceding preposition or a verb causing a word category violation. For the prosodic manipulation, congruent critical words were normally intonated (signaling sentence continuation) while prosodically incongruent critical words signaled sentence end. For the mere prosodic incongruity, a broadly distributed negativity was observed at the critical word-stem (300-500 msec aligned to word onset). In response to a mere syntactic error, a left temporal negativity was elicited in an early time window (200-400 msec aligned to suffix onset), taken to reflect initial phrase structure building processes. In contrast, in response to the combined prosodic-syntactic violation, an early temporal negativity showed up bilaterally at the suffix in the same time window. Our interpretation is that the process of initial structure building as reflected in the early left anterior negativity recruits additional right hemispheric neural resources when the critical word contains both syntactic and prosodic violations. This suggests the immediate influence of phrasal prosody during the initial parsing stage in speech processing.     

Common and distinct neural substrates for pragmatic, semantic, and syntactic processing of spoken sentences: an fMRI study

Extracting meaning from speech requires the use of pragmatic, semantic, and syntactic information. A central question is: Does the processing of these different types of linguistic information have common or distinct neuroanatomical substrates? We addressed this issue using functional magnetic resonance imaging (fMRI) to measure neural activity when subjects listened to spoken normal sentences contrasted with sentences that had either (A) pragmatical, (B) semantic (selection restriction), or (C) syntactic (subcategorical) violations sentences. All three contrasts revealed robust activation of the left-inferior-temporal/fusiform gyrus. Activity in this area was also observed in a combined analysis of all three experiments, suggesting that it was modulated by all three types of linguistic violation. Planned statistical comparisons between the three experiments revealed (1) a greater difference between conditions in activation of the left-superior-temporal gyrus for the pragmatic experiment than the semantic/syntactic experiments; (2) a greater difference between conditions in activation of the right-superior and middle-temporal gyrus in the semantic experiment than in the syntactic experiment; and (3) no regions activated to a greater degree in the syntactic experiment than in the semantic experiment. These data show that, while left- and right-superior-temporal regions may be differentially involved in processing pragmatic and lexico-semantic information within sentences, the left-inferior-temporal/fusiform gyrus is involved in processing all three types of linguistic information. We suggest that this region may play a key role in using pragmatic, semantic (selection restriction), and subcategorical information to construct a higher representation of meaning of sentences.     

The comprehension of sentences with unaccusative verbs in aphasia: a test of the intervener hypothesis

Background: It is well accepted that individuals with agrammatic Broca’s aphasia have difficulty comprehending some sentences with filler-gap dependencies. While investigations of these difficulties have been conducted with several different sentence types (e.g., object relatives, Wh-questions), we explore sentences containing unaccusative verbs, which arguably have a single noun phrase (NP) that is base-generated in object position but then is displaced to surface subject position. Unaccusative verbs provide an ideal test case for a particular hypothesis about the comprehension disorder—the Intervener Hypothesis—that posits that the difficulty individuals with agrammatic Broca’s aphasia have comprehending sentences containing filler-gap dependencies results from similarity-based interference caused by the presence of an intervening NP between the two elements of a syntactic chain.

Aim: To assess a particular account of the comprehension deficit in agrammatic Broca’s aphasia—the Intervener Hypothesis.

Methods & Procedures: We used a sentence–picture matching task to determine if listeners with agrammatic Broca’s aphasia (LWBA) and age-matched neurologically unimpaired controls (AMC) have difficulty comprehending unaccusative verbs when placed in subject relative and complement phrase (CP) constructions.

Outcomes & Results: We found above-chance comprehension of both sentence constructions with the AMC participants. In contrast, we found above-chance comprehension of CP sentences containing unaccusative verbs but poor comprehension of subject relative sentences containing unaccusative verbs for the LWBA.

Conclusions: These results provide support for the Intervener Hypothesis, wherein the presence of an intervening NP between two elements of a filler-gap dependency adversely affects sentence comprehension.     

Pushing around the locus of selection: evidence for the flexible-selection hypothesis

Attention operates at an early stage in some experimental paradigms and at a late stage in others, which suggests that the locus of selection is flexible. The present study was designed to determine whether the locus of selection can vary flexibly within a single experimental paradigm as a function of relatively modest variations in stimulus and task parameters. In the first experiment, a new method for assessing the locus of selection was developed. Specifically, attention can influence perceptual encoding only if it is directed to the target before a perceptual representation of the target has been formed, whereas attention can influence postperceptual processes even if attention is cued after perception is complete. Event-related potentials were used to confirm the validity of this method. The subsequent experiments used cueing tasks in which subjects were required to perceive and remember a set of objects, and the difficulty of the perception and memory components of the task were varied. When the task overloaded perception but not working memory, attention influenced the formation of perceptual representations but not the storage of these representations in memory; when the task overloaded working memory but not perception, attention influenced the transfer of perceptual representations into memory but not the formation of the perceptual representations. Thus, attention operates to select relevant information at whatever stage or stages of processing are overloaded by a particular stimulus-task combination.     

Activation of conflicting responses in Parkinson's disease: evidence for degrading and facilitating effects on response time

Response selection often occurs in a context of competition among conflicting responses. According to recent models, the basal ganglia may play an integral role in resolving this competition by focusing the selection and inhibition of responses. We hypothesized that basal ganglia dysfunction produced by Parkinson's disease (PD) disrupts selection among conflicting responses. Using a version of the Eriksen flanker task, we tested the specific prediction that individuals with PD would experience greater response interference when distractors in the visual field activate a response that conflicts with the target response. In addition, we investigated whether greater response interference induced by these distractors could actually reduce normal response time costs in PD when the task required production of the response opposite the target. Compared to 16 healthy controls (HC), 16 individuals with PD showed an exacerbated slowing when target and distracting stimuli corresponded to conflicting responses. No group differences occurred when targets and distractors corresponded to the same response. Furthermore, the slowing induced by the distractors was reduced in both groups, but more so in PD, when execution of a response opposite the target response (i.e. incompatible response) was required. Moreover, among individuals with PD, the magnitude of the interference produced by the distractors was related to clinical ratings of bradykinesia. These findings are consistent with the hypothesis that basal ganglia dysfunction due to Parkinson's disease disrupts processes that resolve response conflict.     

Right hemisphere specialization for the identification of emotional words and sentences: evidence from stroke patients.

This study examines the contribution of the lexical/verbal channel to emotional processing in 16 right brain-damaged (RBD), 16 left brain-damaged (LBD) and 16 normal control (NC) right-handed adults. Emotional lexical perception tasks were developed; analogous nonemotional tasks were created to control for cognitive and linguistic factors. The three subject groups were matched for gender, age and education. The brain-damaged groups were similar with respect to cerebrovascular etiology, months post-onset, sensory-motor status and lesion location. Parallel emotional and nonemotional tasks included word identification, sentence identification and word discrimination. For both word tasks, RBDs were significantly more impaired than LBDs and NCs in the emotional condition. For all three tasks, RBDs showed a significantly greater performance discrepancy between emotional and nonemotional conditions than did LBDs or NCs. Results were not affected by the valence (i.e. positive/negative) of the stimuli. These findings suggest a dominant role for the right hemisphere in the perception of lexically-based emotional stimuli.     

Apraxia of tool use: More evidence for the technical reasoning hypothesis

Various distinct cognitive processes such as semantic memory, executive planning or technical reasoning have been shown to support tool use. The aim of this study is to investigate the relationship between these processes. To do so, a large apraxia battery was submitted to 16 patients with left brain-damage (LBD) and aphasia and 19 healthy controls. The battery included: classical apraxia tests (Pantomime of Tool Use and Single Tool Use), familiar and novel tool use tests (Tool-Object Pairs and Sequential Mechanical Problem-Solving), semantic memory tests (Recognition of tool utilization gestures and Functional and Categorical Associations) as well as the Tower Of London. The Sequential Mechanical Problem-Solving task is a new task which permits the evaluation of pre-planning in unusual tool use situations. In this task as well as in the Tool-Object Pairs task, participants solved a tool use problem in a Choice and a No-Choice condition to examine the effect of tool selection. Globally, left brain damaged patients were impaired as compared to controls. We found high correlations in left brain damaged patients between performances on classical apraxia tests, familiar and novel tool use tests and Functional and Categorical Associations but no significant association between these performances and Tower Of London or Recognition of tool utilization gestures. Furthermore, the two conditions (Choice and No-Choice) of Tool-Object Pairs and Sequential Mechanical Problem-Solving were associated. In sum, all tasks involving tool use are strongly associated in LBD patients. Moreover, the ability to solve sequential mechanical problems does not depend on executive planning. Also, tool use appears to be associated with knowledge about object function but not with knowledge about tool manipulation. Taken together, these findings indicate that technical reasoning and, to a lesser extent, semantic memory may both play an important role in tool use.     

Investigating the time course of spoken word recognition: electrophysiological evidence for the influences of phonological similarity

Behavioral and modeling evidence suggests that words compete for recognition during auditory word identification, and that phonological similarity is a driving factor in this competition. The present study used event-related potentials (ERPs) to examine the temporal dynamics of different types of phonological competition (i.e., cohort and rhyme). ERPs were recorded during a novel picture-word matching task, where a target picture was followed by an auditory word that either matched the target (CONE-cone), or mismatched in one of three ways: rhyme (CONE-bone), cohort (CONE-comb), and unrelated (CONE-fox). Rhymes and cohorts differentially modulated two distinct ERP components, the phonological mismatch negativity and the N400, revealing the influences of prelexical and lexical processing components in speech recognition. Cohort mismatches resulted in late increased negativity in the N400, reflecting disambiguation of the later point of miscue and the combined influences of top-down expectations and misleading bottom-up phonological information on processing. In contrast, we observed a reduction in the N400 for rhyme mismatches, reflecting lexical activation of rhyme competitors. Moreover, the observed rhyme effects suggest that there is an interaction between phoneme-level and lexical-level information in the recognition of spoken words. The results support the theory that both levels of information are engaged in parallel during auditory word recognition in a way that permits both bottom-up and top-down competition effects.     

Setting the tone: an ERP investigation of the influences of phonological similarity on spoken word recognition in Mandarin Chinese

We investigated the influences of phonological similarity on the time course of spoken word processing in Mandarin Chinese. Event related potentials were recorded while adult native speakers of Mandarin (N=19) judged whether auditory words matched or mismatched visually presented pictures. Mismatching words were of the following nature: segmental (e.g., picture: hua1 'flower'; sound: hua4 'painting'); cohort (e.g., picture: hua1 'flower'; sound: hui1 'gray'); rhyme (e.g., picture: hua1 'flower'; sound: gua1 'melon'); tonal (e.g., picture: hua1 'flower'; sound: jing1 'whale'); unrelated (e.g., picture: hua1 'flower'; sound: lang2 'wolf'). Expectancy violations in the segmental condition showed an early-going modulation of components (starting at 250 ms post-stimulus onset), suggesting that listeners used tonal information to constrain word recognition as soon as it became available, just like they did with phonemic information in the cohort condition. However, effects were less persistent and more left-lateralized in the segmental than cohort condition, suggesting dissociable cognitive processes underlie access to tonal versus phonemic information. Cohort versus rhyme mismatches showed distinct patterns of modulation which were very similar to what has been observed in English, suggesting onsets and rimes are weighted similarly across the two languages. Last, we did not observe effects for whole-syllable mismatches above and beyond those for mismatches in individual components, suggesting the syllable does not merit a special status in Mandarin spoken word recognition. These results are discussed with respect to modifications needed for existing models to accommodate the tonal languages spoken by a large proportion of the world's speakers.     

An ERP investigation on visuotactile interactions in peripersonal and extrapersonal space: evidence for the spatial rule

The spatial rule of multisensory integration holds that cross-modal stimuli presented from the same spatial location result in enhanced multisensory integration. The present study investigated whether processing within the somatosensory cortex reflects the strength of cross-modal visuotactile interactions depending on the spatial relationship between visual and tactile stimuli. Visual stimuli were task-irrelevant and were presented simultaneously with touch in peripersonal and extrapersonal space, in the same or opposite hemispace with respect to the tactile stimuli. Participants directed their attention to one of their hands to detect infrequent tactile target stimuli at that hand while ignoring tactile targets at the unattended hand, all tactile nontarget stimuli, and any visual stimuli. Enhancement of ERPs recorded over and close to the somatosensory cortex was present as early as 100 msec after onset of stimuli (i.e., overlapping with the P100 component) when visual stimuli were presented next to the site of tactile stimulation (i.e., perihand space) compared to when these were presented at different locations in peripersonal or extrapersonal space. Therefore, this study provides electrophysiological support for the spatial rule of visual-tactile interaction in human participants. Importantly, these early cross-modal spatial effects occurred regardless of the locus of attention. In addition, and in line with previous research, we found attentional modulations of somatosensory processing only to be present in the time range of the N140 component and for longer latencies with an enhanced negativity for tactile stimuli at attended compared to unattended locations. Taken together, the pattern of the results from this study suggests that visuotactile spatial effects on somatosensory processing occur prior and independent of tactile-spatial attention.     

Lateralization of prefrontal activity during episodic memory retrieval: evidence for the production-monitoring hypothesis

We propose a new hypothesis concerning the lateralization of prefrontal cortex (PFC) activity during verbal episodic memory retrieval. The hypothesis states that the left PFC is differentially more involved in semantically guided information production than is the right PFC, and that the right PFC is differentially more involved in monitoring and verification than is the left PFC. This "production-monitoring hypothesis" differs from the existing "systematic-heuristic hypothesis," which proposes that the left PFC is primarily involved in systematic retrieval operations, and the right PFC in heuristic retrieval operations. To compare the two hypotheses, we measured PFC activity using positron emission tomography (PET) during the performance of four episodic retrieval tasks: stem cued recall, associative cued recall, context recognition (source memory), and item recognition. Recall tasks emphasized production processes, whereas recognition tasks emphasized monitoring processes. Stem cued recall and context-recognition tasks underscored systematic operations, whereas associative cued recall and item-recognition tasks underscored heuristic operations. Consistent with the production-monitoring hypothesis, the left PFC was more activated for recall than for recognition tasks and the right PFC was more activated for recognition than for recall tasks. Inconsistent with the systematic-heuristic hypothesis, the left PFC was more activated for heuristic than for systematic tasks and the right PFC showed the converse result. Additionally, the study yielded activation differences outside the PFC. In agreement with a previous recall/recognition PET study, anterior cingulate, cerebellar, and striatal regions were more activated for recall than for recognition tasks, and the converse occurred for posterior parietal regions. A right medial temporal lobe region was more activated for stem cued recall and context recognition than for associative cued recall and item recognition, possibly reflecting perceptual integration. In sum, the results provide evidence for the production-monitoring hypothesis and clarify the role of different brain regions typically activated in PET and functional magnetic resonance imaging (fMRI) studies of episodic retrieval.     

Delayed development of proactive response preparation in adolescents: ERP and EMG evidence

The transition from late adolescence to young adulthood is often overlooked in the cognitive neuroscience literature. However this is an important developmental period as even older adolescents have not yet reached adult level ability on many cognitive tasks. Adolescents (16–17-year olds) and young adults (23–30-year olds) were tested on a cued task switching paradigm specifically designed to isolate response preparation from response execution. A combined ERP and eletromyographic (EMG) investigation revealed that adolescents have attenuated contingent negative variation (CNV) activity during response preparation followed by larger P3b amplitude and EMG activity in the incorrect response hand during response execution. This is consistent with deficient response preparation and a reactive control strategy. Conversely young adults engaged increased response preparation followed by attenuated P3b activity and early EMG activity in the correct response hand during response execution which indicates a proactive control strategy. Through real time tracking of response-related processing we provide direct evidence of a developmental dissociation between reactive and proactive control. We assert that adoption of a proactive control strategy by adolescents is an important step in the transition to adulthood.