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Context: Neuromuscular dysfunction is common after anterior cruciate ligament reconstruction (ACL-R). However, little is known about quadriceps spinal-reflex and descending corticomotor excitability after ACL-R. Understanding the effects of ACL-R on spinal-reflex and corticomotor excitability will help elucidate the origins of neuromuscular dysfunction. Context: Neuromuscular dysfunction is common after anterior cruciate ligament reconstruction (ACL-R). However, little is known about quadriceps spinal-reflex and descending corticomotor excitability after ACL-R. Understanding the effects of ACL-R on spinal-reflex and corticomotor excitability will help elucidate the origins of neuromuscular dysfunction. Design: Case-control study. Setting: Laboratory. Patients or Other Participants: A total of 28 patients with unilateral ACL-R (9 men, 19 women; age = 21.28 ± 3.79 years, height = 170.95 ± 10.04 cm, mass = 73.18 ± 18.02 kg, time after surgery = 48.10 ± 36.17 months) and 29 participants serving as healthy controls (9 men, 20 women; age = 21.55 ± 2.70 years, height = 170.59 ± 8.93 cm, mass = 71.89 ± 12.70 kg) volunteered. Main Outcome Measure(s): Active motor thresholds (AMTs) were collected from the vastus medialis (VM) using transcranial magnetic stimulation. We evaluated VM spinal reflexes using the Hoffmann reflex normalized to maximal muscle responses (H : M ratio). Voluntary quadriceps activation was measured with the superimposed-burst technique and calculated using the central activation ratio (CAR). We also evaluated whether ACL-R patients with high or low voluntary activation had different outcomes. Results: The AMT was higher in the injured than in the uninjured limb in the ACL-R group (t27 = 3.32, P = .003) and in the matched limb of the control group (t55 = 2.05, P = .04). The H : M ratio was bilaterally higher in the ACL-R than the control group (F1,55 = 5.17, P = .03). The quadriceps CAR was bilaterally lower in the ACL-R compared with the control group (F1,55 = 10.5, P = .002). The ACL-R group with low voluntary activation (CAR < 0.95) had higher AMT than the control group (P = .02), whereas the ACL-R group with high voluntary activation (CAR > 0.95) demonstrated higher H : M ratios than the control group (P = .05). Conclusions: The higher VM AMT in the injured limbs of ACL-R patients suggested that corticomotor deficits were present after surgery. Higher bilateral H : M ratios in ACL-R patients may be a strategy to reflexively increase excitability to maintain voluntary activation. [ABSTRACT FROM AUTHOR]

The psychological literature has little to say about the constancy of experimental effects, whether those effects are the same for all individuals or vary with the individual. Investigators rarely specify whether the effects noted in research findings apply to every individual or are an average of varying individual effects. Where it does address the matter at all, namely in experimental design texts, the literature gives conflicting messages. It is argued here that a deterministic view of causation, which is implied in most propositions in psychology, leads to the expectation that effects are constant. The problems and confusion that result from viewing such effects as variable are explicated. The consequences of not addressing the issue of effect constancy are to leave statements of findings and propositions unacceptably vague and to encourage, in general, imprecise thinking about substantive matters. [ABSTRACT FROM AUTHOR]

he article discusses the meaning of the interaction concept in scientific discourse and in the analysis of variance and the correspondence between the two. Reasons and examples are given to show that the correspondence is poor. It is recommended that the researcher pay more attention to substantive interactions, of which one way is by using assessment means that are sensitive to the such interactions. [ABSTRACT FROM PUBLISHER]

Focuses on the concept of meta-analysis. Speculation over whether meta-analysis would bring about change in psychological science; Criticism of the concept of meta-analysis.

Presents reasons why the affirmation of the research hypothesis on the basis of the null rejection is unwarranted. Suggestions for the task of corroborating the research hypothesis in science; Insufficient grounds for affirming the research hypothesis; Affirmation of a scientific hypothesis based primarily on substantive evidence that is independent of hypothesis test.

Commentators agree with me that statistical significance does not betoken replicability, but not for the reasons I give. Chow (1998) defends the use of significance tests by arguing that they are useful for assessing the role of chance in findings. I dispute this by pointing out that the Type II error rate may be as high as 1 - ct. Falk (1998) defends Bayesian inference, which was impugned by me. She also makes a case for the use of replications for the purpose of testing hypotheses. I complain that the supporters of Bayesian inference have not explained adequately what its purpose or role in science is, and for this reason it is an impediment to understanding in this area. I also dispute Falk's view of the role of replications in that I would require a successful replication to be one that produces an effect that is clearly discernible, meaning the effect is consistently noticeable with the aid of nothing more than descriptive statistics. [ABSTRACT FROM PUBLISHER]

Meta-analytic writers have argued that psychological science is not working and that the solution to the problem is meta-analysis (MA), quantitative summaries of the research literature. This paper assesses these claims by evaluating MA as a means of scientific discovery and by considering the nature of effective science. It is shown that MA should not be credited as a means of discovery because its database, the research literature, is an untrustworthy source of information about nature. The difference between scientific activity, on the one hand, and literature study, on the other, is highlighted in the analyses. Both MA and empirical science are said to be misguided by a hypothesis-testing approach to science, which approach leads to an obliviousness with respect to mechanisms that underlie phenomena. [ABSTRACT FROM PUBLISHER]