The Dynamical Challenge

Recent studies such as Thelen and Smith (1994), Kelso, (1995), Van Gelder, (1995), Beer, (1995), and others have presented a forceful case for a dynamical systems approach to understanding cognition and adaptive behavior. These studies call into question some foundational assumptions concerning the nature of cognitive scientific explanation and (in particular) the role of notions such as internal representation and computation. These are exciting and important challenges. But they must be handled with care. It is all too easy, in this debate, to lose sight of the explanatorily important issues and to talk at cross-purposes, courtesy of the (surprisingly) various ways in which different theorists often conceive the key terms. The primary goal of the present paper is thus a modest one: to begin to clarify just what is at issue and to highlight some of the most central and pressing concerns. In so doing, we may hope to develop a constructive framework for future debate. In addition, I try to open up a space of intermediate options—ways in which dynamical and representational/computational understandings may sometimes afford complementary (rather than competing) perspectives on adaptive success.     

Cocaine-induced brainstem seizures and behavior

A variety of abnormal sensory/motor behaviors associated with electrical discharges recorded from the bilateral brainstem were induced in adult WKY rats by mechanical (electrode implants) and DC electrical current stimulations and by acute and chronic administration of cocaine. The electrode implant implicated one side or the other of the reticular system of the brainstem but subjects were not incapacitated by the stimulations. Cocaine (40 mg/kg) was injected subcutaneously for an acute experiment and subsequent 20 mg/kg doses twice daily for 3 days in a chronic study. Cocaine generated more abnormal behaviors in the brainstem perturbation group, especially the electrically perturbated subjects. The abnormal behaviors were yawning, retrocollis, hyperactivity, hypersensitivity, “beating drum” behavior, squealing, head bobbing, circling, sniffing, abnormal posturing, and facial twitching. Shifts in the power frequency spectra of the discharge patterns were noted between quiet and pacing behavioral states. Hypersensitivity to various auditory, tactile, and visual stimulation was present and shifts in the brainstem ambient power spectral frequency occurred in response to tactile stimulation. These findings suggest that the brainstem generates and propagates pathological discharges that can be elicited by mechanical and DC electrical perturbation. Cocaine was found to activate the discharge system and thus induce abnormal behaviors that are generated at the discharge site and at distant sites to which the discharge propagates. Cognitive functions may also be involved since dopaminergic and serotonergic cellular elements at the brainstem level are also implicated.     

The Milan method—a preliminary critique*

The elegance of the techniques developed by the Milan group has tended to blind family therapists to the many problems inherent in their approach. A close reading of their work uncovers many ethical and political issues which need to be addressed. This paper is a preliminary attempt to develop a critique of the group's method which recapitulates some of the most alienating aspects of the traditional medical model. It will concentrate solely on a critical reading of Paradox and Counterparadox and will not seek to come to terms with the more recent evolution of the Milan school.     

Binocular detection by normal and stereoblind observers

Binocular forced-choice detection performance was measured in three stereoblind observers and four observers with normal stereopsis. Detection rates of normal observers were greater than expected from probability summation, while those of the stereoblind observers were near or at a level expected from probability. It is concluded that binocular summation is reduced or absent in stereoblind persons.     

The reading grade level of common measures in child and adolescent clinical psychology

The purpose of this article is to provide easily accessible readability information for 49 parent- and 35 child- and adolescent-report measures commonly used by clinicians and researchers. There is a great deal of variability in reading ability required across measures. The majority of parent-report measures (65%) required reading ability above the 8th grade level. The average child-/adolescent-report measure required reading ability above the 6th grade level. Given the potential contribution of readability to a measure's reliability, validity, and overall utility, examining and accounting for readability should be a more common practice in test construction and administration.     

Windows into nothingness: terror management, meaninglessness, and negative reactions to modern art

Why do people dislike art that they find meaningless? According to terror management theory, maintaining a basic meaningful view of reality is a key prerequisite for managing concerns about mortality. Therefore, mortality salience should decrease liking for apparently meaningless art, particularly among those predisposed to unambiguous knowledge. Accordingly, mortality salience diminished affection for modern art in Study 1, and this effect was shown in Study 2 to be specific to individuals with a high personal need for structure (PNS). In Studies 3 and 4, mortality salient high-PNS participants disliked modern art unless it was imbued with meaning, either by means of a title or a personal frame of reference induction. Discussion focused on the roles of meaninglessness, PNS, and art in terror management.     

Associative learning of likes and dislikes: Some current controversies and possible ways forward

Evaluative conditioning (EC) is one of the terms that is used to refer to associatively induced changes in liking. Many controversies have arisen in the literature on EC. Do associatively induced changes in liking actually exist? Does EC depend on awareness of the fact that stimuli are associated? Is EC resistant to extinction? Does attention help or hinder EC? As an introduction to this special issue, we will discuss the extent to which the papers that are published in this issue help to resolve some of the controversies that surround EC. We also speculate about possible boundary conditions of EC and attempt to reconcile conflicting results on the functional properties of EC.     

The hippocampal contribution to “Learning and memory”: Information retrieval and comparison

The effects of limbic system after-discharges and ablation upon learning were investigated in 113 adult cats. Learning tasks consisted of active and passive avoidance and pattern and size discrimination. Limbic system after-discharges interfered with performance in learned-avoidance and size-discrimination paradigms. Discharges implicating the ventral hippocampus were the most effective in producing performance decrements; dorsal hippocampal discharges were least effective. The greater the involvement of brain-stem structures by propagated activity, the greater the decrement. There was no motor impairment. Size-discrimination response is impaired to a greater degree than shockavoidance response during limbic discharges. The degree of impairment is in part a function of the type of sensory stimulus and response contingency used. Hippocampal ablation resulted in impairment (response latency changes) in both active and passive avoidance tasks. Acquisition was not impaired. Hippocampal ablation facilitated the development of a stronger position habit in the pattern-discrimination task. Learning deficits which occurred were attributed to impairment of retrieval and comparator mechanisms of neural function. Results support the argument that defective retrieval and/or comparator mechanisms may account for the impaired learning of a diversity of tasks, from simple to complex.     

Tonotypic cortical representation in man (case report)

Cortical stimulation—evoked perception of tones differing in pitch suggests that the perception of pitch may be discretely organized in the human auditory parakoniocortex. Findings, obtained from a neurosurgical patient undergoing temporal lobectomy, are discussed with reference to anatomical and functional considerations of the auditory parakoniocortex in humans. These tonotypic findings are potentially significant since, as previously reported (see references in Discussion section), auditory sensations have not been analyzed in relation to perceptual categories of pitch. Address correspondence to: Department of Speech Pathology and Audiology, Marquette University, Milwaukee, Wisconsin 53233.