Mechanisms underlying writing and speech in aphasia

As a parallel to the dual decoding concept for processing of written language we proposed that phonological encoding does not necessarily occur in writing and that the phonemic and graphemic subsystems can be independent on the one-word level. This hypothesis was tested by comparing oral and written performance in a picture-naming task in Broca's and Wernicke's aphasics. In addition, the residual tacit knowledge of the orthographic properties of the names of the pictures was examined with a multiple-choice recognition task. The principal finding is that Broca's aphasics who were better in written than in oral naming showed more graphemically and semantically motivated errors than aphasics who were better in oral than in written naming, the latter producing more phonemically motivated errors. This result supports the dual encoding concept for writing on the singleword level, implying a direct route from the mental lexicon to the graphemic system in parallel with a route mediated by the phonemic system. Multiple-choice recognition was found to be superior to both oral and written performance in both Broca's and Wernicke's aphasics.     

How do we process novel conceptual combinations in context?

Most theories of how people interpret novel noun-noun combinations (e.g., ghost forest) do not sufficiently address the role of context, which is surprising given that novel combinations are generally encountered in discourse contexts. We evaluated three hypotheses for the role of context in interpretation. The generation hypothesis states that interpretation is based on sense generation both in and out of context. The anaphor resolution hypothesis states that interpretation initially involves identifying a referent from the prior discourse context, and meaning generation occurs only if anaphoric processing fails. The dual-process hypothesis states that sense generation and anaphor resolution operate in parallel, and both may influence initial interpretation. In two experiments, we examined reading times on novel combinations when the dominant meaning (most likely interpretation) or subordinate meaning (infrequent interpretation) preceded or followed the combination in text. Results supported the dual-process hypothesis.     

汉语句子格角色分配的一种神经网络方法

提出了一个基于分布式表征的计算模型,通过并行分布加工方式完成六类汉语句子的格角色分配任务。模型是一个四层的前传网络,包括输入层（词的分布式表征层）,两个隐层,输出层（格角色层）;其中第一隐层的一部分反馈到输入层。模型采用误差反传算法,通过提供学习样本和目标输出,不断调整三个权值矩阵,使得网络稳定时能得到正确的结果。经过训练后的网络具有一定的稳定性和鲁棒性。还对这种方法与传统的符号处理方法作了比较和分析。     

How do we process novel conceptual combinations in context?

Most theories of how people interpret novel noun–noun combinations (e.g., ghost forest) do not sufficiently address the role of context, which is surprising given that novel combinations are generally encountered in discourse contexts. We evaluated three hypotheses for the role of context in interpretation. The generation hypothesis states that interpretation is based on sense generation both in and out of context. The anaphor resolution hypothesis states that interpretation initially involves identifying a referent from the prior discourse context, and meaning generation occurs only if anaphoric processing fails. The dual-process hypothesis states that sense generation and anaphor resolution operate in parallel, and both may influence initial interpretation. In two experiments, we examined reading times on novel combinations when the dominant meaning (most likely interpretation) or subordinate meaning (infrequent interpretation) preceded or followed the combination in text. Results supported the dual-process hypothesis.     

Tracking the continuity of language comprehension: computer mouse trajectories suggest parallel syntactic processing

Although several theories of online syntactic processing assume the parallel activation of multiple syntactic representations, evidence supporting simultaneous activation has been inconclusive. Here, the continuous and non-ballistic properties of computer mouse movements are exploited, by recording their streaming x, y coordinates to procure evidence regarding parallel versus serial processing. Participants heard structurally ambiguous sentences while viewing scenes with properties either supporting or not supporting the difficult modifier interpretation. The curvatures of the elicited trajectories revealed both an effect of visual context and graded competition between simultaneously active syntactic representations. The results are discussed in the context of 3 major groups of theories within the domain of sentence processing.     

On putting apples into bottles — A problem of polysemy

An experiment was designed in such a manner that a sentence could be recalled given a certain cue only if the subject's encoding of the sentence included details and involved distinctions in the senses of words which could not have been part of the correct dictionary readings for these words. The most plausible interpretation of the results is that comprehension of a sentence entails constructing a particularized and elaborated mental representation, and that this process depends more heavily on knowledge of the world and analysis of context than is generally appreciated. It is claimed that existing associative or semantic network theories would be strained to accommodate the data.     

Uncovering mental processes with factorial experiments

The analysis of reaction time (RT) additivity and interactions via factorial manipulation is a widely used and potentially powerful tool for elucidating mental processing; however, current implementation is limited by the scope of systems for which predictions are available, as well as statistical weakness. Predictions for an expanded set of system dimensions (serial/parallel, independent/dependent, and selective/nonselective influence) are given. The theorems are not limited to particular families of distributions. Statistical considerations are examined in the context of an exemplary nonadditive parallel system which adequately fits “additive” data but will only be rejected as additive when power is increased beyond the traditional criteria.     

Computational Evidence for the Subitizing Phenomenon as an Emergent Property of the Human Cognitive Architecture

A computational modeling approach was used to test one possible explanation for the limited capacity of the subitizing phenomenon. Most existing models of this phenomenon associate the subitizing span with an assumed structural limitation of the human information processing system. In contrast, we show how this limit might emerge as the combinatorics of the space of enumeration problems interacts with the human cognitive architecture in the context of an enumeration task. Subitizing‐like behavior was generated in two different models of enumeration, one based on the ACT‐R cognitive architecture and the other based on the principles of parallel distributed processing (PDP). Our results provide good qualitative fits to results obtained in a variety of empirical studies.     

Pupillometry reveals processing load during spoken language comprehension

This study investigated processing effort by measuring peoples’ pupil diameter as they listened to sentences containing a temporary syntactic ambiguity. In the first experiment, we manipulated prosody. The results showed that when prosodic structure conflicted with syntactic structure, pupil diameter reliably increased. In the second experiment, we manipulated both prosody and visual context. The results showed that when visual context was consistent with the correct interpretation, prosody had very little effect on processing effort. However, when visual context was inconsistent with the correct interpretation, prosody had a large effect on processing effort. The interaction between visual context and prosody shows that visual context has an effect on online processing and that it can modulate the influence of linguistic sources of information, such as prosody. Pupillometry is a sensitive measure of processing effort during spoken language comprehension.     

Retrieval processes in recall

A reaction time (RT) paradigm was developed to study retrieval processes in paired associate (PA) recall. Prior to the experimental session, subjects learned lists of PAs (varying in length from three to 24 pairs); during the experimental session, subjects' RT to say the response word from the onset of a visually presented stimulus word was measured. The implications of several classes of retrieval models were discussed in the context of this paradigm. The shape of the RT-list length function, practice, and sequential effects were all of interest in distinguishing among models. Four experiments were reported which were designed to (1) establish the baseline effects in this paradigm, (2) determine which of these effects should be attributed to the retrieval stage of processing, and (3) investigate the effect of semantic memory in this task. Results suggest that simple serial scanning models are inadequate to handle the data from this task. Strength, direct-access, or parallel processing models, on the other hand, seem to capture the qualitative effects present in our experiments. When a strength model was formalized and fit to the data from Experiment I, it was found that a two-trace version gave good quantitative fits while a one-trace version did not, suggesting that both short- and long-term memory independently contribute in this task.     

On pedagogy

Humans are adapted to spontaneously transfer relevant cultural knowledge to conspecifics and to fast-learn the contents of such teaching through a human-specific social learning system called 'pedagogy' (Csibra & Gergely, 2006). Pedagogical knowledge transfer is triggered by specific communicative cues (such as eye-contact, contingent reactivity, the prosodic pattern of 'motherese', and being addressed by one's own name). Infants show special sensitivity to such 'ostensive' cues that signal the teacher's communicative intention to manifest new and relevant knowledge about a referent object. Pedagogy offers a novel functional perspective to interpret a variety of early emerging triadic communicative interactions between adults and infants about novel objects they are jointly attending to. The currently dominant interpretation of such triadic communications (mindreading) holds that infants interpret others' object-directed manifestations in terms of subjective mental states (such as emotions, dispositions, or intentions) that they attribute to the other person's mind. We contrast the pedagogical versus the mindreading account in a new study testing 14-month-olds' interpretation of others' object-directed emotion expressions observed in a communicative cueing context. We end by discussing the far-reaching implications of the pedagogical perspective for a wide range of early social-cognitive competences, and for providing new directions for future research on child development.     

The interaction of semantic memory with storage and retrieval processes

A procedure for separating storage from retrieval (R. Chechile & D. L. Meyer, Journal of Mathematical Psychology, 1976, 14, 430–437) lead to the conclusion that memory development involves changes in both storage and retrieval. Nevertheless, these changes resulted from the interaction of storage and retrieval mechanisms with the age-related elaboration of the semantic memory system. This study shows that the memory improvement with age, between kindergarten and second grade, vanished when the meaningfulness of the materials were equated. The most plausible interpretation of the results is the hardware invariance hypothesis. According to that hypothesis, the memory apparatus for information processing is constant across ages, but the hardware is used more effectively if there is a better-developed semantic memory system.     

Content and context in incremental processing: “the ham sandwich” revisited

The interplay of content and context is observable in a moment to moment manner as propositional content unfolds. The current contribution illustrates this through data from real-time language comprehension indicating that propositional content is not computed in isolation but relies in important ways on context during every step of the computation of meaning. The relevant notion of context that we have to adopt includes all aspects of possible worlds and draws on a variety of knowledge representations, which in a first processing phase serve to generate expectations for upcoming words. In a second phase, the discourse representation is assessed and if necessary updated by means of inferential reasoning and enrichment to reflect the speaker’s intended meaning.     

A learning algorithm for boltzmann machines

The computational power of massively parallel networks of simple processing elements resides in the communication bandwidth provided by the hardware connections between elements. These connections can allow a significant fraction of the knowledge of the system to be applied to an instance of a problem in a very short time. One kind of computation for which massively parallel networks appear to be well suited is large constraint satisfaction searches, but to use the connections efficiently two conditions must be met: First, a search technique that is suitable for parallel networks must be found. Second, there must be some way of choosing internal representations which allow the preexisting hardware connections to be used efficiently for encoding the constraints in the domain being searched. We describe a general parallel search method, based on statistical mechanics, and we show how it leads to a general learning rule for modifying the connection strengths so as to incorporate knowledge about a task domain in an efficient way. We describe some simple examples in which the learning algorithm creates internal representations that are demonstrably the most efficient way of using the preexisting connectivity structure.     

On the optimality of serial and parallel processing in the psychological refractory period paradigm: Effects of the distribution of stimulus onset asynchronies

Within the context of the psychological refractory period (PRP) paradigm, we developed a general theoretical framework for deciding when it is more efficient to process two tasks in serial and when it is more efficient to process them in parallel. This analysis suggests that a serial mode is more efficient than a parallel mode under a wide variety of conditions and thereby suggests that ubiquitous evidence of serial processing in PRP tasks could result from performance optimization rather than from a structural bottleneck. The analysis further suggests that the experimenter-selected distribution of stimulus onset asynchronies (SOAs) influences the relative efficiency of the serial and parallel modes, with a preponderance of short SOAs favoring a parallel mode. Experiments varying the distribution of SOAs were conducted, and the results suggest that there is a shift from a more serial mode to a more parallel mode as the likelihood of short SOAs increases.     

The group psychotherapist as contemporary mystic: a bionic object relations perspective

Mysticism is a heightened awareness facilitating intuitive knowledge of group realities. In contrast to logical positivism, in which scientific knowledge consists of logic applied to a set of observations, the author holds that mystical awareness is pertinent to the conduct of therapy groups. The work of Bion, and also so-called "structuralist" theories, postulate pre-given templates that inform experience. The application of mystical thought to group consultation, leadership, and transformation of the self is discussed. The group context which allows for mystical experience is called the "sacred space." To emphasize the sacredness of the group, a kabbalist parallel to early development and projective identification is used to show how sacred metaphor and myth can enrich interpretation in groups.     

Developmental levels of processing in metaphor interpretation

We outline a theory of metaphor interpretation. The theory posits varying levels of semantic processing and formalizes them in terms of kinds of semantic-mapping operators that transform properties of the metaphoric vehicle (i.e., predicate) into properties of the metaphoric topic (i.e., subject). We used cognitive-developmental theory to estimate the mental-processing complexity of the various mapping operators, and thereby to predict the timing of their emergence in childhood, and to construct a measure of the metaphoric-processing levels. Metaphor interpretations collected from children (aged 6-12 years) and adults were coded and scored according to the processing levels. In two separate developmental studies, processing score increased with age in a predictable way. Growth in a mental-attentional resource accounted for much of the developmental variance in metaphor interpretation. Possible moderating effects of knowledge and context are discussed.     

Reversal operations after brain damage

The ability to perform reversals—that is, the appreciation of the relationship between original and transformed states of knowledge—is critical to human thought processes. In order to assess whether a number of “special-purpose processors” are responsible for reversal operations, depending on the particular context in which the reversal is couched, or whether a single “core processing mechanism” subserves a critical aspect of reversal operations regardless of the specific context, patients with localized brain damage were asked to solve eight reversal problems. Visual and auditory reversals mediated by linguistic and non-linguistic symbol systems were presented. The findings demonstrate that patients with insult to the anterior portion of the right hemisphere encounter more difficulty performing reversals than patients with right posterior insult, Broca's aphasics, and fluent aphasics. This is regardless of the symbol system mediating the reversal, regardless of the modality of presentation, and regardless of the amount of available processing time. Subjects with insult to the posterior region of the left hemisphere or the right hemisphere also exhibit some difficulty solving reversal problems, although their difficulties appear modality specific. These data lend support to the claim that a core processing mechanism may play a critical role in the performance of reversal operations.     

Implicit learning of tonality: a self-organizing approach

Tonal music is a highly structured system that is ubiquitous in our cultural environment. We demonstrate the acquisition of implicit knowledge of tonal structure through neural self-organization resulting from mere exposure to simultaneous and sequential combinations of tones. In the process of learning, a network with fundamental neural constraints comes to internalize the essential correlational structure of tonal music. After learning, the network was run through a range of experiments from the literature. The model provides a parsimonious account of a variety of empirical findings dealing with the processing of tone, chord, and key relationships, including relatedness judgments, memory judgments, and expectancies. It also illustrates the plausibility of activation being a unifying mechanism underlying a range of cognitive tasks.