On thought experiments as a priori science

Against Norton's claim that all thought experiments can be reduced to explicit arguments, I defend Brown's position that certain thought experiments yield a priori knowledge. They do this, I argue, not by allowing us to perceive “Platonic universals” (Brown), even though they may contain non‐propositional components that are epistemically indispensable, but by helping to identify certain tacit presuppositions or “natural interpretations” (Feyerabend's term) that lead to a contradiction when the phenomenon is described in terms of them, and by suggesting a new natural interpretation in terms of which the phenomenon can be redescribed free of contradiction.     

The ethics and politics of small sacrifices in stem cell research

Pluripotent human stem cell research may offer new treatments for hundreds of diseases, but opponents of this research argue that such therapy comes attached to a Faustian bargain: cures at the cost of the destruction of many frozen embryos. The National Bioethics Advisory Commission (NBAC), government officials, and many scholars of bioethics, including, in these pages, John Robertson, have not offered an adequate response to ethical objections to stem cell research. Instead of examining the ethical issues involved in sacrificing human embryos for the goal of curing fatal and disabling diseases, they seek to either dismiss the moral concerns of those with objections or to find an "accomodation" with those opposed to stem cell research. An ethical argument can be made that it is justifiable to modify or destroy certain human embryos in the pursuit of cures for dread and lethal diseases. Until this argument is made, the case for stem cell research will rest on political foundations rather than on the ethical foundations that the funding of stem cell research requires.     

Implicit learning: An analysis of the form and structure of a body of tacit knowledge

Subjects learned implicitly the underlying structure of an artificial language by memorizing a set of representative exemplars from the language. The form and structure of their resulting knowledge of the language was evaluated and analyzed over a four day period by several procedures: (a) solving anagrams from the language, (b) determining the well-formedness of novel letter strings, and (c) providing detailed introspective reports. Several important implications about implicit acquisition of a novel complex system emerged. First, the memorial representation of a structured system is acquired through the dual operations of a differentiation-like process based upon relational invariances and a configurational process based upon overall structure. Second, the form of tacit knowledge is an abstract representation of the intrinsic structure of the stimulus field. Third, while the ability to make explicit what is known implicitly increases with performance levels, the conscious apprehension of structure always lags behind what is known unconsciously.     

Time-sharing SKED and OS/8: A new version

A new time-sharing SKED program has been developed to simultaneously conduct up to 12 behavioral experiments while the OS/8 operating system is used in the “background.” The new system provides improved control over the SKED program while allowing the experimenter to develop new programs or analyze data during the experimental session. A minimum of 16K of memory and an OS/8 device is required to use this system.     

The Validity of Construction Workers' and Students' Perceptions of Each Other: A Research Note

Following the spring 1970 confrontations between undergraduate college students and construction workers in lower Manhattan, a study of attitudes of a sample of undergraduates and construction workers was conducted. One hunderd Columbia University undergraduates and 100 apprentice construction workers were asked to indicate their level of agreement with 10 statements which were intended to embody "basic American tenets". The respondents within each group were also asked to predict the attitude that a member of the other group would hold. A "liberal/conservative" dichotomy was developed for the instrument by having independent judges categorize each of the 10 items as representing a "liberal" or a "conservative" attitude.
The expectations that student responses would be more liberal than construction worker responses and that each group would perceive this difference were tested and supported. The expectation that students perceive construction workers to be even more conservative than the workers report themselves to be was also supported. But the construction workers did not demonstrate the expected exaggeration of the students' liberalism.     

Detectability of the deletion of a tone from a tone-plus-noise background

The deletion of a 1,000-Hz tone from a tone-plus-noise background is much harder for humans to detect than the insertion of the same tone into a background of noise. A mathematically ideal O, oblivious to the context in which an observation interval occurs, performs equally well under conditions of insertion and deletion. Human listeners, not oblivious to context, produced the function d_s = 0.036 E/N_o under deletion; the slope of this linear function is no more than half that of the typical slope of the comparable insertion function. The underlying reasons for the superiority of detection of insertion to that of deletion remain unclear.     

Parametric aspects of tactile resolution

Three parameters of tactile resolution (area, force, and pressure of stimulation) were investigated in three experiments. A two-point discrimination task was presented by means of an electromechanical stimulator permitting precise control of all relevant stimulus variables. The results indicated a positive linear effect of area, a curvilinear effect of force, and no effect of pressure on the threshold for resolution of two tactile stimuli. The findings are in agreement with data on the influence of the same parameters in visual resolution.     

Effects of short-term counseling on Career Maturity of tenth-grade students

The effectiveness of short-term counseling on Career Maturity of tenth-grade students as measured by the Career Maturity Inventory was studied. The Career Maturity Attitude Scale and the Self Appraisal subscale of the Competence Test were administered to a random sample (87 subjects) of tenth-grade students. The subjects whose scores fell below the mean were assigned randomly to experimental and control groups. The experimental group (17 subjects) received special counseling during a short term of 6 wk. Using repeated measures of analysis of variance, a statistically significant interaction was found with both the Self Appraisal subscale scores and the Total scale scores. Results indicate that career maturity as a developmental process can be measured and facilitated through counseling.     

Relative persistence of avoidance and positively reinforced behavior

In one experiment with rats, and a second with pigeons, subjects were trained on a schedule in which identical response dependencies applied to intermittent receipt of positive reinforcement (PR) for one group and avoidance (AV) of shock for a second group. After obtaining comparable stable training performance for groups PR and AV, persistence tests were conducted with a traditional extinction (EXT) procedure vs. response-independent (FREE) delivery of positive reinforcers or shocks. In both experiments, response elimination was rapid in EXT for groups PR and AV, and responding tended to be maintained in groups PR and AV in the FREE persistence test. These results contradict the widely held assumption that avoidance behavior is unusually resistant to extinction, and they call for a re-examination of elimination of avoidance responding.