It is currently debated whether the meanings of words and objects are represented, in whole or in part, in a modality-specific format—the embodied cognition hypothesis. I argue that the embodied/disembodied cognition debate is either largely resolved in favor of the view that concepts are represented in an amodal format, or at a point where the embodied and disembodied approaches are no longer coherently distinct theories. This merits reconsideration of what the available evidence can tell us about the structure of the conceptual system. We know that the conceptual system engages, online, with sensory and motor content. This frames a new question: How is it that the human conceptual system is able to disengage from the sensorimotor system? Answering this question would say something about how the human mind is able to detach from the present and extrapolate from finite experience to hypothetical states of how the world could be. It is the independence of thought from perception and action that makes human cognition special—and that independence is guaranteed by the representational distinction between concepts and sensorimotor representations.
Mulatti and Coltheart (2011, this issue) review and summarize several findings from the picture-word interference paradigm that the authors argue challenge the Response Exclusion Hypothesis. However, the hypothesis they take to be the Response Exclusion Hypothesis is not that theory—it is an account developed by Mulatti and Coltheart that holds that target naming latencies in the picture-word paradigm are affected only by the process of excluding the distractor word (and by nothing else). We consider some of the background assumptions implicit in Mulatti and Coltheart’s discussion that may have led to this misattribution. Finally, we report a replication of an effect originally described by Dalrymple-Alford (1972) that serves as an empirical basis for reiterating the main points of our proposal and outlining the challenges that lie ahead.
In recent decades, researchers have exploited semantic context effects in picture naming tasks in order to investigate the mechanisms involved in the retrieval of words from the mental lexicon. In the blocked naming paradigm, participants name target pictures that are either blocked or not blocked by semantic category. In the continuous naming task, participants name a sequence of target pictures that are drawn from multiple semantic categories. Semantic context effects in both tasks are a highly reliable phenomenon. The empirical evidence is, however, sparse and inconsistent when the target stimuli are printed-words instead of pictures. In the first part of the present study we review the empirical evidence regarding semantic context effects with written-word stimuli in the blocked and continuous naming tasks. In the second part, we empirically test whether semantic context effects are transferred from picture naming trials to word reading trials, and from word reading trials to picture naming trials. The results indicate a transfer of semantic context effects from picture naming to subsequently read within-category words. There is no transfer of semantic effects from target words that were read to subsequently named within-category pictures. These results replicate previous findings (Navarrete et al., 2010) and are contrary to predictions from a recent theoretical analysis by Belke (2013). The empirical evidence reported in the literature together with the present results, are discussed in relation to current accounts of semantic context effects in speech production.
speech production; word reading; semantic context effect; lexical access; picture naming
The thesis of embodied cognition has developed as an alternative to the view that cognition is mediated, at least in part, by symbolic representations. A useful testing ground for the embodied cognition hypothesis is the representation of concepts. An embodied view of concept representation argues that concepts are represented in a modality-specific format. I argue that questions about representational format are tractable only in the context of explicit hypotheses about how information spreads among conceptual representations and sensorimotor systems. When reasonable alternatives to the embodied cognition hypothesis are clearly defined, the available evidence does not distinguish between the embodied cognition hypothesis and those alternatives. Furthermore, I argue, the available data that are theoretically constraining indicate that concepts are more than just sensory and motor content. As such, the embodied/nonembodied debate is either largely resolved or at a point where the embodied and nonembodied approaches are no longer coherently distinct theories. This situation merits a reconsideration of what the available evidence can tell us about the structure of the conceptual system. I suggest that it is the independence of thought from perception and action that makes human cognition special— and that independence is made possible by the representational distinction between concepts and sensorimotor representations.
embodied cognition; amodal representations; simulation; conceptual representation; neuropsychology
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.
speech production; semantic interference; semantic facilitation; blocked naming; cyclic naming; lexical retrieval
Color is important in our daily interactions with objects, and plays a role in both low- and high-level visual processing. Previous neuropsychological studies have shown that color perception and object-color knowledge can doubly dissociate, and that both can dissociate from processing of object form. We present a case study of an individual who displayed an impairment for knowledge of the typical colors of objects, with preserved color perception and color naming. Our case also presented with a pattern of, if anything, worse performance for naming living items compared to nonliving things. The findings of the experimental investigation are evaluated in light of two theories of conceptual organization in the brain: the Sensory Functional Theory and the Domain-Specific Hypothesis. The dissociations observed in this case compel a model in which sensory/motor modality and semantic domain jointly constrain the organization of object knowledge.
In the last decade, the debate about the causal role of the motor system in speech perception has been reignited by demonstrations that motor processes are engaged during the processing of speech sounds. However, the exact role of the motor system in auditory speech processing remains elusive. Here we evaluate which aspects of auditory speech processing are affected, and which are not, in a stroke patient with dysfunction of the speech motor system. The patient’s spontaneous speech was marked by frequent phonological/articulatory errors, and those errors were caused, at least in part, by motor-level impairments with speech production. We found that the patient showed a normal phonemic categorical boundary when discriminating two nonwords that differ by a minimal pair (e.g., ADA-AGA). However, using the same stimuli, the patient was unable to identify or label the nonword stimuli (using a button-press response). A control task showed that he could identify speech sounds by speaker gender, ruling out a general labeling impairment. These data suggest that the identification (i.e. labeling) of nonword speech sounds may involve the speech motor system, but that the perception of speech sounds (i.e., discrimination) does not require the motor system. This means that motor processes are not causally involved in perception of the speech signal, and suggest that the motor system may be used when other cues (e.g., meaning, context) are not available.
apraxia of speech; categorical perception; motor theory of speech perception; mirror neurons
Orbital frontal cortex (OFC) is known to play a role in object recognition by generating “first-pass” hypotheses about the identity of naturalistic images based on low spatial frequency (SF) information. These hypotheses are evaluated by more detailed (and slower) ventral visual pathway processes. While it has been suggested on theoretical grounds, it remains unknown whether OFC also receives postrecognition feedback about stimulus identity. We used a novel paradigm in the context of functional magnetic resonance imaging that permits the first few hundred milliseconds of object recognition to be spread out over 120 s. OFC shows a robust response to low and relatively high SFs, whereas ventral stream regions display unimodal response distributions shifted toward high SFs. These findings in OFC were modulated by hemisphere, with right OFC differentially responding to low SFs and left OFC differentially responding to high SFs. Psychophysical experiments confirmed that the same ranges of SFs preferred by ventral stream regions are critical for determining the accuracy and speed of object recognition. Our findings indicate that OFC accesses global form (low SF information, right OFC) and object identity (high SF information, left OFC), and suggest that OFC receives feedback about the accuracy of its initial hypothesis regarding stimulus identity.
fMRI; object recognition; psychophysics; spatial frequency; spatial vision
How are lexical representations retrieved during sign production? Similar to spoken languages, lexical representation in sign language must be accessed through semantics when naming pictures. However, it remains an open issue whether lexical representations in sign language can be accessed via routes that bypass semantics when retrieval is elicited by written words. Here we address this issue by exploring under which circumstances sign retrieval is sensitive to semantic context. To this end we replicate in sign language production the cumulative semantic cost: The observation that naming latencies increase monotonically with each additional within-category item that is named in a sequence of pictures. In the experiment reported here, deaf participants signed sequences of pictures or signed sequences of Italian written words using Italian Sign Language. The results showed a cumulative semantic cost in picture naming but, strikingly, not in word naming. This suggests that only picture naming required access to semantics, whereas deaf signers accessed the sign language lexicon directly (i.e., bypassing semantics) when naming written words. The implications of these findings for the architecture of the sign production system are discussed in the context of current models of lexical access in spoken language production.
Here we find, using functional Magnetic Resonance Imaging (fMRI), that object manipulation knowledge is accessed by way of the ventral object processing pathway. We exploit the fact that parvocellular channels project to the ventral but not the dorsal stream, and show that increased neural responses for tool stimuli are observed in the inferior parietal lobule when those stimuli are visible only to the ventral object processing stream. In a control condition, tool-preferences were observed in a superior and posterior parietal region for stimuli titrated so as to be visible by the dorsal visual pathway. Functional connectivity analyses confirm the dissociation between sub-regions of parietal cortex according to whether their principal afferent input is via the ventral or dorsal visual pathway. These results challenge the ‘Embodied Hypothesis of Tool Recognition’, according to which tool identification critically depends on simulation of object manipulation knowledge. Instead, these data indicate that retrieval of object-associated manipulation knowledge is contingent on accessing the identity of the object, a process that is subserved by the ventral visual pathway.
Emotional and affective processing imposes itself over cognitive processes and modulates our perception of the surrounding environment. In two experiments, we addressed the issue of whether nonconscious processing of affect can take place even under deep states of unawareness, such as those induced by interocular suppression techniques, and can elicit an affective response that can influence our understanding of the surrounding environment. In Experiment 1, participants judged the likeability of an unfamiliar item—a Chinese character—that was preceded by a face expressing a particular emotion (either happy or angry). The face was rendered invisible through an interocular suppression technique (continuous flash suppression; CFS). In Experiment 2, backward masking (BM), a less robust masking technique, was used to render the facial expressions invisible. We found that despite equivalent phenomenological suppression of the visual primes under CFS and BM, different patterns of affective processing were obtained with the two masking techniques. Under BM, nonconscious affective priming was obtained for both happy and angry invisible facial expressions. However, under CFS, nonconscious affective priming was obtained only for angry facial expressions. We discuss an interpretation of this dissociation between affective processing and visual masking techniques in terms of distinct routes from the retina to the amygdala.
Nonconscious affect; Affective priming; Continuous flash suppression; Retinotectal route; Emotion; Amygdala
Motor theories of perception posit that motor information is necessary for successful recognition of actions. Perhaps the most well known of this class of proposals is the motor theory of speech perception, which argues that speech recognition is fundamentally a process of identifying the articulatory gestures (i.e. motor representations) that were used to produce the speech signal. Here we review neuropsychological evidence from patients with damage to the motor system, in the context of motor theories of perception applied to both manual actions and speech. Motor theories of perception predict that patients with motor impairments will have impairments for action recognition. Contrary to that prediction, the available neuropsychological evidence indicates that recognition can be spared despite profound impairments to production. These data falsify strong forms of the motor theory of perception, and frame new questions about the dynamical interactions that govern how information is exchanged between input and output systems.
speech perception; language comphrension; mirror neuron system; apraxia; motor theory of perception
A unifying theme that cuts across all research areas and techniques in the cognitive and brain sciences is whether there is specialization of function at levels of processing that are ‘abstracted away’ from sensory inputs and motor outputs. Any theory that articulates claims about specialization of function in the mind/brain confronts the following types of interrelated questions, each of which carries with it certain theoretical commitments. What methods are appropriate for decomposing complex cognitive and neural processes into their constituent parts? How do cognitive processes map onto neural processes, and at what resolution are they related? What types of conclusions can be drawn about the structure of mind from dissociations observed at the neural level, and vice versa? The contributions that form this Special Issue of Cognitive Neuropsychology represent recent reflections on these and other issues from leading researchers in different areas of the cognitive and brain sciences.
Information about object-associated manipulations is lateralized to left parietal regions, while information about the visual form of tools is represented bilaterally in ventral occipito-temporal cortex. It is unknown how lateralization of motor-relevant information in left hemisphere dorsal regions may affect the visual processing of manipulable objects. We used a lateralized masked priming paradigm to test for a Right Visual Field (RVF) advantage in tool processing. Target stimuli were tools and animals, and briefly presented primes were identical to, or scrambled versions of the targets. In Experiment 1, primes were presented either to the left or right of the centrally presented target, while in Experiment 2 primes were presented in one of 8 locations arranged radially around the target. In both experiments there was a RVF advantage in priming effects for tool but not for animal targets. Control experiments showed that participants were at chance for matching the identity of the lateralized primes in a picture-word matching experiment, and also ruled out a general RVF speed-of-processing advantage for tool images. These results indicate that the overrepresentation of tool knowledge in the left hemisphere affects visual object recognition, and suggest that interaction between the dorsal and ventral streams occurs during object categorization.
Research on patients with apraxia, a deficit in skilled action, has shown that the ability to use objects may be differentially impaired relative to knowledge about object function. Here we show, using a modified neuropsychological test, that similar dissociations can be observed in response times in healthy adults. Participants were asked to decide which two of three presented objects shared the same manipulation or the same function; triads were presented in picture- and word-format, and responses were made manually (button press) or with a basic level naming response (verbally). For manual responses (Experiment 1) participants were slower to make manipulation judgments for word stimuli compared to picture stimuli, while there was no difference between word and picture stimuli for function judgments. For verbal naming responses (Experiment 2) participants were again slower for manipulation judgments over word stimuli compared to picture stimuli; however, and in contrast to Experiment 1, function judgments over word stimuli were faster than function judgments over picture stimuli. These data support the hypotheses that knowledge of object function and knowledge of object manipulation correspond to dissociable types of object knowledge, and that simulation over motor information is not necessary in order to retrieve knowledge of object function.
It is widely argued that the ability to recognize and identify manipulable objects depends on the retrieval and simulation of action-based information associated with using those objects. Evidence for that view comes from fMRI studies that have reported differential BOLD contrast in dorsal visual stream regions when participants view manipulable objects compared with a range of baseline categories. An alternative interpretation is that processes internal to the ventral visual pathway are sufficient to support the visual identification of manipulable objects and that the retrieval of object-associated use information is contingent on analysis of the visual input by the ventral stream. Here, we sought to distinguish these two perspectives by exploiting the fact that the dorsal stream is largely driven by magnocellular input, which is biased toward low spatial frequency visual information. Thus, any tool-selective responses in parietal cortex that are driven by high spatial frequencies would be indicative of inputs from the ventral visual pathway. Participants viewed images of tools and animals containing only low, or only high, spatial frequencies during fMRI. We find an internal parcellation of left parietal “tool-preferring” voxels: Inferior aspects of left parietal cortex are driven by high spatial frequency information and have privileged connectivity with ventral stream regions that show similar category preferences, whereas superior regions are driven by low spatial frequency information. Our findings suggest that the automatic activation of complex object-associated manipulation knowledge is contingent on analysis of the visual input by the ventral visual pathway.
Functional magnetic resonance imaging has been used to identify the different networks in the brain that underpin the use of tools by humans.
fMRI; tool use; intentions; action; neuroscience; motor; Human
Various forms of category-specificity have been described at both the cognitive and neural levels, inviting the inference that different semantic domains are processed by distinct, dedicated mechanisms. Here we argue for an extension of a Domain-Specific interpretation to these phenomena that is based on network-level analyses of functional coupling among brain regions. On this view, domain-specificity in one region of the brain emerges because of innate connectivity with a network of regions that also process information about that domain. Recent findings are reviewed that converge with this framework, and a new direction is outlined for understanding the neural principles that shape the organization of conceptual knowledge.
The cyclic naming paradigm, in which participants are slower to name pictures blocked by semantic category than pictures in an unrelated context, offers a window into the dynamics of the mapping between lexical concepts and words. Here we provide evidence for the view that incremental adjustments to the connection weights from semantics to lexical items provides an elegant explanation of a range of observations within the cyclic naming paradigm. Our principal experimental manipulation is to vary the within-category semantic distance among items that must be named together in a block. In the first set of experiments we find that naming latencies are, if anything, faster for within-category semantically close blocks compared to within-category semantically far blocks, for the first presentation of items. This effect can be explained by the fact that there will be more spreading activation, and thus greater priming at the lexical level, for within-category semantically close blocks than within-category semantically far blocks. We test this explanation by inserting intervening filler items (geometric shapes), and show as predicted, that while intervening unrelated trials abolish short-lived semantic priming effects, the long-lag interference effect that is characteristic of this paradigm is unaffected. These data place new constraints on explanations of the cyclic naming effect, and related phenomena, within a model of language production.
lexical access; speech production; semantic interference; semantic facilitation; semantic distance; cyclic naming paradigm
Much of mental life consists in thinking about object concepts that are not currently within the scope of perception. The general system that enables multiple representations to be maintained and compared is referred to as ‘working memory’ (Repovš and Baddeley, 2006), and involves regions in medial and lateral parietal and frontal cortex (e.g., Smith and Jonides, 1999). It has been assumed that the contents of working memory index information in regions of the brain that are critical for processing and storing object knowledge. To study the processes involved in thinking about common object concepts, we used event related fMRI to study BOLD activity while participants made judgments of conceptual similarity over pairs of sequentially presented auditory words. Through a combination of conventional fMRI analysis approaches and multi-voxel pattern analysis (MVPA), we show that the brain responses associated with the second word in a pair carry information about the conceptual similarity between the two members of the pair. This was the case in frontal and parietal regions involved in the working memory and decision components of the task for both analysis approaches. However, in other regions of the brain, including early visual regions, MVPA permitted classification of semantic distance relationships where conventional averaging approaches failed to show a difference. These findings suggest that diffuse and statistically sub-threshold ‘scattering’ of BOLD activity in some regions may carry substantial information about the contents of mental representations.
The ventral stream refers to a neural pathway that projects from early visual areas through to anterior temporal cortex, and comprises regions in ventral and lateral occipital-temporal cortex. The ventral stream is critical for recognizing visually presented objects. Functional imaging studies of the human brain have shown that different regions within the ventral stream show differential activation to nonliving (tools, houses) and living stimuli (animals, faces). The causes of these category preferences are widely debated. Using functional magnetic resonance imaging, we find that the same regions of the ventral stream that show category preferences for nonliving stimuli and animals in sighted adults, show the same category preferences in adults who are blind since birth. Both blind and sighted participants had larger blood oxygen-level dependent (BOLD) responses in the medial fusiform gyrus for nonliving stimuli compared to animal stimuli, and differential BOLD responses in lateral occipital cortex for animal stimuli compared to nonliving stimuli. These findings demonstrate that the medial-to-lateral bias by conceptual domain in the ventral stream does not require visual experience in order to develop, and suggest the operation of innately determined domain-specific constraints on the organization of object knowledge.
Tool use depends on processes represented in distinct regions of left parietal cortex. We studied the role of visual experience in shaping neural specificity for tools in parietal cortex by using functional magnetic resonance imaging with sighted, late-blind, and congenitally blind participants. Using a region-of-interest approach in which tool-specific areas of parietal cortex were identified in sighted participants viewing pictures, we found that specificity in blood-oxygen-level-dependent responses for tools in the left inferior parietal lobule and the left anterior intraparietal sulcus is independent of visual experience. These findings indicate that motor- and somatosensory-based processes are sufficient to drive specificity for representations of tools in regions of parietal cortex. More generally, some aspects of the organization of the dorsal object-processing stream develop independently of the visual information that forms the major sensory input to that pathway in sighted individuals.
tools; blind humans; conceptual knowledge; dorsal visual pathway; fMRI
The principles driving the organization of the ventral object-processing stream remain unknown. Here we show that stimulus-specific repetition suppression (RS) in one region of the ventral stream is biased according to motor-relevant properties of objects. Quantitative analysis confirmed that this result was not confounded with similarity in visual shape. A similar pattern of biases in RS according to motor-relevant properties of objects was observed in dorsal stream regions in the left hemisphere. These findings suggest that neural specificity for ‘tools’ in the ventral stream is driven by similarity metrics computed over motor-relevant information represented in dorsal structures. Support for this view is provided by converging results from functional connectivity analyses of the fMRI data and a separate neuropsychological study. More generally, these data suggest that a basic organizing principle giving rise to ‘category-specificity’ in the ventral stream may involve similarity metrics computed over information represented elsewhere in the brain.
We report a new pattern of usage in current, spoken Italian that has implications for both psycholinguistic models of language production and linguistic theories of language change. In Italian, gender agreement is mandatory for both singular and plural nouns. However, when two or more nouns of different grammatical gender appear in a conjoined noun phrase (NP), masculine plural agreement is required. In this study, we combined on-line and off-line methodologies in order to assess the mechanisms involved in gender marking in the context of multiple referents. The results of two pronoun production tasks showed that plural feminine agreement was significantly more difficult than plural masculine agreement. In a separate study using offline judgements of acceptability, we found that agreement violations in Italian are tolerated more readily in the case of feminine conjoined noun phrases (e.g., la mela e la banana ‘the:fem apple:fem and the: fem banana: fem’) than masculine conjoined noun phrases (e.g., il fiore e il libro ‘the:mas flower: mas and the:mas book:mas’). Implications of these results are discussed both at the level of functional architecture within the language production system and at the level of changes in language use.*