Modeling semantic memory: Effects of presenting semantic information in different modalities

How is semantic information from different modalities integrated and stored? If related ideas are encountered in French and English, or in pictures and sentences, is the result a single representation in memory, or two modality-dependent ones? Subjects were presented with items in different modalities, then were asked whether or not subsequently presented items were identical with the former ones. Subjects frequently accepted translations and items semantically consistent with those presented earlier as identical, although not as often as they accepted items actually seen previously. The same pattern of results was found when the items were French and English sentences, and when they were pictures and sentences. The results can be explained by the hypothesis that subjects integrate information across modalities into a single underlying semantic representation. A computer model, embodying this hypothesis, made predictions in close agreement with the data.     

Logical competence and transitive inference in young children

Five-year-old children were trained on the length relationships between the adjacent members of a five-term series of sticks. They were then tested on their abilities (1) to judge the length relationships between nonadjacent pairs of the series, and (2) to incorporate an unseen novel stick into the series through inference. Children who were trained with sticks of markedly different lengths succeeded on the first test but not the second; they apparently relied on memory for the absolute lengths of the sticks. Children in the other groups succeeded on both tests. The critical factor in inducing the use of seriation and transitivity seemed to be the elimination of alternative solutions.     

Development of voice recognition: parallels with face recognition.

Encoding and subsequent recognition of unfamiliar voices was examined in children, aged 6 to 16, and in adults. Performance changed markedly with age, improving sharply between ages 6 and 10, with 10-year-olds approaching adult levels. After age 10 accuracy declined significantly but returned to the adult level by age 14. The course of development closely matches that recently documented for the ability to encode and recognize unfamiliar faces. Several parallels between voice recognition and face recognition are discussed.     

Artificial intelligence,language, and the study of knowledge

This paper studies the relationship of Artificial Intelligence to the study of language and the representation of the underlying knowledge which supports the comprehension process. It develops the view that intelligence is based on the ability to use large amounts of diverse kinds of knowledge in procedural ways, rather than on the possession of a few general and uniform principles. The paper also provides a unifying thread to a variety of recent approaches to natural language comprehension. We conclude with a brief discussion of how Artificial Intelligence may have a radical impact on education if the principles which it utilizes to explore the representation and use of knowledge are made available to the student to use in his own learning experiences.     

Perceptual and conceptual organization of facial emotions: Hemispheric differences

Patients with lesions to either the right or left hemisphere and control subjects were asked to judge the similarity of pairs of photographs of a person displaying different emotions, and of pairs of emotion words. The results were submitted to a multidimensional scaling analysis. Right-hemisphere-damaged subjects were found to be more impaired at perceiving facial emotions than were left-hemisphere-damaged subjects or controls, and this impairment was not confined to the perception of a subset of facial emotions nor to judging emotional valence (Pleasantness versus Unpleasantness). Rather, subtle impairments in perceiving a wide range of facial emotions were found, mostly concerning differentiation of the Positive-Negative and Attention-Rejection dimensions, and concerning the strategies the subjects used to make their judgments. The right-hemisphere-damaged subjects performed comparably to controls in their ratings of emotion words, suggesting that their ability to conceptualize emotional states was intact and that their impairment was strictly in the perception of emotion.     

The processing of fundamental frequency in a dichotic matching task

The temporal characteristics of auditory memory were investigated using a reaction time paradigm. The study attempted to determine whether or not there are functionally distinct left and right hemisphere components of auditory memory with different capacities for the retention of nonlinguistic information, such as fundamental frequency, over the course of several seconds. The results indicated that fundamental frequency information in auditory memory remains substantially unchanged over the course of 2 sec. No evidence was found for the existence of separate left and right hemisphere components of auditory memory with different temporal characteristics. The implications of this finding for the organization of auditory memory in the brain are discussed.     

The identification of stuttering: Can you look and tell

This investigation focussed on how observers identify stutterers. It was found that stutterers are identified most correctly under visual circumstances as compared to auditory and combined auditory-visual conditions. Therefore, the reduction of stuttering should include removal of noticeable, interfering, and unnecessary nonverbal behaviors, particularly mouth and nostril movements.     

Three conditions on conceptual naturalness

Human infants are predisposed to organize their experience in terms of certain concepts and not in terms of others. The favored concepts are called natural, the remainder, unnatural. A major problem in psychology is to state a principled distinction between the two kinds of concepts. Toward this end, the present paper offers three, formal necessary conditions on the naturalness of concepts. The conditions attempt to link the problem of naturalness to the distinctions between sense versus nonsense, simplicity versus complexity, and validity versus invalidity.     

Arousal and memory: phasic measures of arousal in a free recall task.

EEG alpha activity and skin potential were monitored during word presentation in a single trial free recall task. Phasic changes in EEG alpha and skin potential, co-occurring with word onset, were positively related to recall at an immediate retention interval (2 min) but not after a delay (45 min). The results were interpreted as supporting the extension of Routtenberg's (1968) two-arousal system hypothesis to human memory. Arousal was viewed as affecting memory during the attribute encoding stage of memory storage.     

The functional equivalence of mental images and errors of movement.

Four experiments are reported demonstrating that mental images are functionally equivalent to physical errors of movement in producing changes in visual-motor coordination, at both central and peripheral levels of the visual-motor system. In the first experiment, subjects in one condition pointed at a target seen through laterally displacing prisms and were instructed to imagine pointing errors identical to those recorded previously for subjects in a separate condition who actually observed their pointing errors. Changes in pointing accuracy during adaptation procedures and visual-motor aftereffects following these procedures for subjects who imagined their errors were proportional to visual-motor shifts and aftereffects for subjects who observed their errors. In the second experiment, these same imagery instructions resulted in identical pointing shifts and aftereffects even in the case where prisms did not displace the target. The third experiment showed that when subjects believe that their mental images of pointing errors do not correspond to their actual pointing errors, pointing aftereffects result that are characteristic of the processing of error information at peripheral, but not central, levels of the visual motor system. The final experiment showed that when subjects do believe that their images of pointing errors correspond to actual pointing errors, but imagine the pointing movement itself in addition to their errors, pointing aftereffects result that are characteristic of the processing of error information at central, but not peripheral, levels of the visual-motor system. Contributions to visual-motor aftereffects from these two levels appear to be additive. Another significant result was that, in the imagery feedback conditions of each experiment, subjects who gave high ratings of vividness to their mental imagery showed the greatest magnitude of pointing aftereffects. These findings establish that mental images for errors of movement can produce stable visual-motor changes that cannot be accounted for simply by subjects' expectations regarding the actual consequences of their actions.     

Explaining 'The Hardness of the Logical Must': Wittgenstein on Grammar, Arbitrariness and Logical Necessity

This paper explains (in Part A) Wittegnstein's understanding of the 'grammar' of our (or any) language, tracing its origins in the Tractatus's concept of logical syntax, and then examining the senses in which Wittegnstein, in his later work, viewed grammar as being 'arbitrary'. Then, armed with this understanding, it moves on (in Part B) to the task of examining how, within the framework of a Wittegnsteinian view of language, we should understand the inescapable 'compellingness' of logical necessity – what Wittegnstein calls the "hardness of the logical must". Whereas it is often thought that Wittegnstein's views on the nature of the 'grammar' of our concpets leads him towards a vitiatingly conventionalist or anti-realist understanding of necessity, in which its logical 'superhardness' becomes problematic, this paper will argue that there is actually no such tension in Wittegnstein's thought. In fact, it will be argued, an understanding of the ways in which our conceptual grammar is arbitrary casts a great deal of light on how it is that our concepts can nevertheless support a logically superhard, and normatively commanding, notion of necessity. In support of this view, I distinguish Wittegnstein's views on necessity from the 'classical' conventionalism of the Vienna Circle, and from the radical conventionalism of Michael Dummett, and defend Wittegnstein's view from a powerful recent attack from Quassim Cassam.     

Actuality, Necessity, and Logical Truth

The traditional view that all logical truths are metaphysically necessary has come under attack in recent years. The contrary claim is prominent in David Kaplan’s work on demonstratives, and Edward Zalta has argued that logical truths that are not necessary appear in modal languages supplemented only with some device for making reference to the actual world (and thus independently of whether demonstratives like ‘I’, ‘here’, and ‘now’ are present). If this latter claim can be sustained, it strikes close to the heart of the traditional view. I begin this paper by discussing and refuting Zalta’s argument in the context of a language for propositional modal logic with an actuality connective (section 1). This involves showing that his argument in favor of real world validity his preferred explication of logical truth, is fallacious. Next (section 2) I argue for an alternative explication of logical truth called general validity. Since the rule of necessitation preserves general validity, the argument of section 2 provides a reason for affirming the traditional view. Finally (section 3) I show that the intuitive idea behind the discredited notion of real world validity finds legitimate expression in an object language connective for deep necessity. Earlier versions of this paper were read at the universities of Graz, Maribor, and Salzburg, and at a workshop on the philosophy of logic at the National Autonomous University of Mexico (UNAM) in Mexico City. My thanks to those present at these events for many helpful suggestions. Thanks are also due to an anonymous referee for Philosophical Studies.     

Frege,Boolos, and Logical Objects

In this paper, the authors discuss Frege's theory of logical objects (extensions, numbers, truth-values) and the recent attempts to rehabilitate it. We show that the eta relation George Boolos deployed on Frege's behalf is similar, if not identical, to the encoding mode of predication that underlies the theory of abstract objects. Whereas Boolos accepted unrestricted Comprehension for Properties and used the eta relation to assert the existence of logical objects under certain highly restricted conditions, the theory of abstract objects uses unrestricted Comprehension for Logical Objects and banishes encoding (eta) formulas from Comprehension for Properties. The relative mathematical and philosophical strengths of the two theories are discussed. Along the way, new results in the theory of abstract objects are described, involving: (a) the theory of extensions, (b) the theory of directions and shapes, and (c) the theory of truth values.