Developmental changes in the semantic processing of pictures and words

Second- and fifth-graders' semantic decision times for pictures and words were analyzed relative to the predictions derived from unitary- and dual-memory models. At both grade levels, word-word response latencies were greater than picture-word latencies which, in turn, were greater than picture-picture latencies. An interaction between Grade and Condition indicated that verbal access times decreased more than pictorial access times. The data fit the predictions of a memory model postulating category storage in a single memory system as opposed to simultaneous representation in verbal and nonverbal memory systems. It was concluded that with increasing experience verbal access to this single semantic system is more rapid.     

Determinants of famous name processing speed: Age of acquisition versus semantic connectedness

The age of acquisition (AoA) and the amount of biographical information known about celebrities have been independently shown to influence the processing of famous people. In this experiment, we investigated the facilitative contribution of both factors to famous name processing. Twenty-four mature adults participated in a familiarity judgement task, in which the names of famous people were grouped orthogonally by AoA and by the number of bits of biographical information known about them (number of facts known; NoFK). Age of acquisition was found to have a significant effect on both reaction time (RT) and accuracy of response, but NoFK did not. The RT data also revealed a significant AoA × NoFK interaction. The amount of information known about a celebrity played a facilitative role in the processing of late-acquired, but not early-acquired, celebrities. Once AoA is controlled, it would appear that the semantic system ceases to have a significant overall influence on the processing of famous people. The pre-eminence of AoA over semantic connectedness is considered in the light of current theories of AoA and how their influence might interact.     

Age-of-acquisition effects in semantic processing tasks

In two experiments, we examined whether word age-of-acquisition (AoA) is a reliable predictor of processing times in semantic tasks. In the first task, participants were asked to say the first associate that came to mind when they saw a stimulus word; the second task involved a semantic categorisation between words with a definable meaning and first names. In both tasks, there were significantly faster responses to earlier-acquired than to later-acquired words. On the basis of these results, we argue that age-of-acquisition effects do not originate solely from the speech output system, but from the semantic system as well.     

Number-of-features effects and semantic processing

Participants list many semantic features for some concrete nouns (e.g., lion) and fewer for others (e.g., lime; McRae, de Sa, & Seidenberg, 1997). Pexman, Lupker, and Hino (2002) reported faster lexical decision and naming responses for high number of features (NOF) words than for low-NOF words. In the present research, we investigated the impact of NOF on semantic processing. We observed NOF effects in a self-paced reading task when prior context was not congruent with the target word (Experiment 1) and in a semantic categorization task (concrete vs. abstract; Experiment 2A). When we narrowed our stimuli to include high- and low-NOF words from a single category (birds), we found substantial NOF effects that were modulated by the specificity of the categorization task (Experiments 3A, 3B, and 3C). We argue that these results provide support for distributed representation of word meaning.     

Age of acquisition effects in vocabulary learning

Two experiments examined whether the age of acquisition (AoA) of a concept influences the speed at which native English speakers are able to name pictures using a newly acquired second language (L2) vocabulary. In Experiment 1, participants were taught L2 words associated with pictures. In Experiment 2 a second group of participants were taught the same words associated with L1 translations. Following training both groups performed a picture naming task in which they were asked to name pictures using the newly acquired words. Significant AoA effects were observed only in Experiment 1, in that participants were faster at naming pictures representing early acquired relative to late acquired concepts. The results suggest that the AoA of a concept can exert influence over processing which is independent of the AoA of the word form. The results also indicate that different training methods may lead to qualitative differences in the nature of the links formed between words and concepts during the earliest stages of second language learning.     

The perception of semantic relations in pictures

Three picture processing experiments are reported that present evidence of an “agent advantage effect,” that is, faster processing of the performer of the action depicted the agent of the action than of the element acted upon (the patient). Experiment 1 demonstrated the effect in a paradigm in which reaction time to manually indicate the location of a target (agent or patient) was faster for agent targets. Experiment 2 demonstrated that the critical time required for subjects to encode the agent was shorter than the time required for encoding patients. Experiment 3 again demonstrated the agent advantage effect in a directed attention paradigm. Together, the results of the experiments indicated that subjects were able to encode agent information faster than patient information. The results also indicated that subjects did not adopt a strategy whereby encoding of patient information was necessarily dependent upon encoding agent information.     

Event-related potentials and the semantic matching of pictures

Event-related potentials (ERPs) were recorded from one midline and three pairs of lateral electrodes while subjects determined whether pairs of sequentially presented pictures were semantically associated. The ERPs evoked by the second picture of each pair differed as a consequence of whether it was associated with its predecessor, such that ERPs to nonassociated pictures were more negative-going than those to associated items. These differences resulted from the modulation of two ERP components, one frontally distributed and centered on an N300 deflection, the other distributed more widely over the scalp and encompassing an N450 deflection. The modulation of N450 is interpreted as further evidence that the "N400" ERP component is sensitive to semantic relationships between nonverbal stimuli. The earlier N300 effects, which do not appear to occur when ERPs are evoked by semantically primed and unprimed words, could suggest that the semantic processing of pictorial stimuli involves neural systems different from those associated with the semantic processing of words.     

Examining lateralized semantic access using pictures

A divided visual field (DVF) experiment examined the semantic processing strategies employed by the cerebral hemispheres to determine if strategies observed with written word stimuli generalize to other media for communicating semantic information. We employed picture stimuli and vary the degree of semantic relatedness between the picture pairs. Participants made an on-line semantic relatedness judgment in response to sequentially presented pictures. We found that when pictures are presented to the right hemisphere responses are generally more accurate than the left hemisphere for semantic relatedness judgments for picture pairs. Furthermore, consistent with earlier DVF studies employing words, we conclude that the RH is better at accessing or maintaining access to information that has a weak or more remote semantic relationship. We also found evidence of faster access for pictures presented to the LH in the strongly-related condition. Overall, these results are consistent with earlier DVF word studies that argue that the cerebral hemispheres each play an important and separable role during semantic retrieval.     

Hunting for individual differences in cognitive processes: Verbal ability and semantic processing of pictures and words

Semantic category decisions were examined for single picture and word stimuli. Consistent with previous research, pictures yielded faster latencies than words and both showed significant taxonomic frequency effects for positive decisions. The results are interpreted in terms of general models for semantic verification, in which both pictures and words involve access to the same underlying semantic knowledge base. The latter conclusion was supported by correlation-regression analyses on individual item latencies. Variations in processing latency as a function of stimulus mode, taxonomic frequency, and type of decision were analyzed with respect to adult individual differences in verbal ability, The results uniformly failed to show a significant relationship between verbal ability and any processing speed measure. The lack of any significant relationship is discussed in light of previous results on verbal ability and processing speed, suggesting obvious qualifications of past results and possible reinterpretations of the meaning of previously obtained speed differences.     

Long-term age of acquisition effects in famous name processing

The age of acquisition (AoA) effect refers to the processing advantage that words, objects, and people learnt earlier in life hold over those acquired later. We explored the long-term effects of AoA on performance, using naturally occurring famous names, acquired by participants cumulatively over three decades. We manipulated AoA by selecting celebrities who had first become known to our participants in the 1960s, 1970s, or 1980s and explored the effects of age by testing participants aged in their 40s, 50s, or 60s. Seventy-two participants made push-button 'Yes-No' familiarity decision judgements to the printed names of celebrities. We found a significant AoA effect. A linear increase in reaction time was uncovered, with the participants being fastest to respond to the 1960s celebrities, followed by those from the 1970s, and being slowest to respond to celebrities from the 1980s. There was no age × AoA interaction, although the AoA effect was most pronounced in the oldest participant group. Our data demonstrate the long-term persistent influence of AoA on processing speed. Moreover, they indicate that the effects of AoA are much more subtle than simply reflecting a difference between the earliest acquired stimuli in a processing domain and all later acquired items.     

The dependence of semantic relatedness effects upon prime processing

The semantic relationship between a prime and a target word has been shown to affect the speed at which the target word is processed. This series of experiments investigated how the semantic priming effect is influenced by the nature of the task performed on the prime word. Subjects were asked to perform either a naming or a letter-search task on the prime word and either a lexical-decision or color-naming task on the target word. When the primes were named, response times for the target words were facilitated in the lexical-decision task and inhibited in the color-naming task. However, these effects were eliminated or reduced to an insignificant level when the primes were searched for letters. We suggest that in order to produce the usual priming effect, the primes have to be processed for meaning rather than probed for constituents.     

Effects of semantic context in the naming of pictures and words

Two experiments investigated whether lexical retrieval for speaking can be characterized as a competitive process by assessing the effects of semantic context on picture and word naming in German. In Experiment 1 we demonstrated that pictures are named slower in the context of same-category items than in the context of items from various semantic categories, replicating findings by Kroll and Stewart (Journal of Memory and Language, 33 (1994) 149). In Experiment 2 we used words instead of pictures. Participants either named the words in the context of same- or different-category items, or produced the words together with their corresponding determiner. While in the former condition words were named faster in the context of same-category items than of different-category items, the opposite pattern was obtained for the latter condition. These findings confirm the claim that the interfering effect of semantic context reflects competition in the retrieval of lexical entries in speaking.     

Age of acquisition affects early orthographic processing during Chinese character recognition

Three experiments investigated age of acquisition (AoA) effects on early orthographic processing during Chinese character recognition. In Experiment 1, we measured the accuracy of identification of brief masked characters, accuracy was higher for early compared to late acquired characters. In Experiment 2, the visual duration threshold (VDT) was measured for both early and late acquired Chinese characters. The results showed that early acquired characters were successfully identified at shorter display durations than late acquired characters. Significant AoA effects were also found in Experiment 3, using a lexical decision task requiring mainly orthographic processing (discriminating real Chinese characters from orthographically illegal and unpronounceable characters). In summary, three experiments provide converging empirical evidence, for AoA effects on the early orthographic processing stages of Chinese character recognition. These results suggest that AoA effects during word identification go beyond the phonological or semantic processing stages. These results aslo provide cross-linguistic evidence for an AoA effect on early perceptual processing during identification.     

The effect of age of acquisition in visual word processing: further evidence for the semantic hypothesis

The authors investigated whether the meaning of visually presented words is activated faster for early-acquired words than for late-acquired words. They addressed the issue using the semantic Simon paradigm. In this paradigm, participants are instructed to decide whether a stimulus word is printed in uppercase or lowercase letters. However, they have to respond with a verbal label ("living" or "nonliving") that is either congruent with the meaning of the word (e.g., saying "living" to the stimulus DOG) or incongruent (e.g., saying "nonliving" to the stimulus dog). Results showed a significant congruency effect that was stronger for early-acquired words than for late-acquired words. The authors conclude that the age of acquisition is an important variable in the activation of the meaning of visually presented words.     

Age of acquisition effects in adult lexical processing reflect loss of plasticity in maturing systems: insights from connectionist networks

Early learned words are recognized and produced faster than later learned words. The authors showed that such age of acquisition effects are a natural property of connectionist models trained by back-propagation when patterns are introduced at different points into training and learning of early and late patterns is cumulative and interleaved. Analysis of hidden unit activations indicated that the age of acquisition effect reflects a gradual reduction in network plasticity and a consequent failure to differentiate late items as effectively as early ones. Further simulations examined the effects of vocabulary size, learning rate, sparseness of coding, use of a modified learning algorithm, loss of early items, acquisition of very late items, and lesioning the network. The relationship between age of acquisition and word frequency was explored, including analyses of how the relative influence of these factors is modulated by introducing weight decay.     

The effects of perceptual load on semantic processing under inattention

Inattentional blindness refers to a failure to consciously detect an irrelevant object that appears without any expectation when attention is engaged with another task. The perceptual load theory predicts that task-irrelevant stimuli will reach awareness only when the primary task is of low load, which allows processing resources to spill over to processing task-irrelevant stimuli as well. We studied whether perceptual load has an effect on inattentional blindness for a task-irrelevant stimulus whose meaning is or is not relevant to the attentional goals of the observer. In the critical trial, a word appeared without any expectation in the center of a display of attended pictures. The results showed that, under both high and low load, unexpected words belonging to the attended semantic category were detected more often than semantically unrelated words. These results imply that task-irrelevant stimuli, whose meanings are relevant to the observer’s task, enter awareness irrespective of perceptual load.     

Age of acquisition effects on the functional organization of language in the adult brain

Using functional magnetic resonance imaging (fMRI), we neuroimaged deaf adults as they performed two linguistic tasks with sentences in American Sign Language, grammatical judgment and phonemic-hand judgment. Participants’ age-onset of sign language acquisition ranged from birth to 14 years; length of sign language experience was substantial and did not vary in relation to age of acquisition. For both tasks, a more left lateralized pattern of activation was observed, with activity for grammatical judgment being more anterior than that observed for phonemic-hand judgment, which was more posterior by comparison. Age of acquisition was linearly and negatively related to activation levels in anterior language regions and positively related to activation levels in posterior visual regions for both tasks.     

Emotional speech processing: disentangling the effects of prosody and semantic cues

To inform how emotions in speech are implicitly processed and registered in memory, we compared how emotional prosody, emotional semantics, and both cues in tandem prime decisions about conjoined emotional faces. Fifty-two participants rendered facial affect decisions (Pell, 2005a), indicating whether a target face represented an emotion (happiness or sadness) or not (a facial grimace), after passively listening to happy, sad, or neutral prime utterances. Emotional information from primes was conveyed by: (1) prosody only; (2) semantic cues only; or (3) combined prosody and semantic cues. Results indicated that prosody, semantics, and combined prosody-semantic cues facilitate emotional decisions about target faces in an emotion-congruent manner. However, the magnitude of priming did not vary across tasks. Our findings highlight that emotional meanings of prosody and semantic cues are systematically registered during speech processing, but with similar effects on associative knowledge about emotions, which is presumably shared by prosody, semantics, and faces.     

Emotional speech processing: Disentangling the effects of prosody and semantic cues

To inform how emotions in speech are implicitly processed and registered in memory, we compared how emotional prosody, emotional semantics, and both cues in tandem prime decisions about conjoined emotional faces. Fifty-two participants rendered facial affect decisions (Pell, 2005a), indicating whether a target face represented an emotion (happiness or sadness) or not (a facial grimace), after passively listening to happy, sad, or neutral prime utterances. Emotional information from primes was conveyed by: (1) prosody only; (2) semantic cues only; or (3) combined prosody and semantic cues. Results indicated that prosody, semantics, and combined prosody–semantic cues facilitate emotional decisions about target faces in an emotion-congruent manner. However, the magnitude of priming did not vary across tasks. Our findings highlight that emotional meanings of prosody and semantic cues are systematically registered during speech processing, but with similar effects on associative knowledge about emotions, which is presumably shared by prosody, semantics, and faces.