Effects of Category-Learning on Categorization An Analysis of Inference-Based and Classification-Based Learning

It is widely acknowledged that categories have many functions, but few studies have actually addressed the impact of these functions on the way categories are learned. For instance, many categorization experiments predominantly rely on classification-based incremental learning. The problem with this approach is that it implicitly assumes that the function of categorization is separable from the way that categories are learned. In this study, we examined the relation between learning and the subsequent use of categories by contrasting three types of category-learning methods — inference-based, classification-based, and a combination of these methods. The results of the experiment indicate that there is an intricate relationship between category-learning and subsequent use of the category. The results further suggest that different processing modes may have been adopted by subjects in the different learning conditions

Treating cisplatin-resistant cancer: a systematic analysis of oxaliplatin or paclitaxel salvage chemotherapy

Objective: To examine the pre-clinical and clinical evidence for the use of oxaliplatin or paclitaxel salvage chemotherapy in patients with cisplatin-resistant cancer. Methods: Medline was searched for 1) Cell models of acquired resistance reporting cisplatin, oxaliplatin and paclitaxel sensitivities and 2) Clinical trials of single agent oxaliplatin or paclitaxel salvage therapy for cisplatin/carboplatin-resistant ovarian cancer. Results: Oxaliplatin - Oxaliplatin is widely regarded as being active in cisplatin-resistant cancer. In contrast, data in cell models suggests that there is cross-resistance between cisplatin and oxaliplatin in cellular models with resistance levels which reflect clinical resistance (<10 fold). Oxaliplatin as a single agent had a poor response rate in patients with cisplatin-resistant ovarian cancer (8%, n=91). Oxaliplatin performed better in combination with other agents for the treatment of platinum-resistant cancer suggesting that the benefit of oxaliplatin may lie in its more favourable toxicity and ability to be combined with other drugs rather than an underlying activity in cisplatin resistance. Oxaliplatin therefore should not be considered broadly active in cisplatin-resistant cancer. Paclitaxel – Cellular data suggests that paclitaxel is active in cisplatin-resistant cancer. 68.1% of cisplatin-resistant cells were sensitive to paclitaxel. Paclitaxel as a single agent had a response rate of 22% in patients with platinum-resistant ovarian cancer (n = 1918), a significant increase from the response of oxaliplatin (p<0.01). Paclitaxel-resistant cells were also sensitive to cisplatin, suggesting that alternating between agents may be beneficial. Studies of single agent paclitaxel in platinum-resistant ovarian cancer where patients had previously received paclitaxel had an improved response rate of 35.3% n=232 (p<0.01), suggesting that pre-treatment with paclitaxel improves the response of salvage paclitaxel therapy. Conclusions: Cellular models reflect the resistance observed in the clinic as the cross resistant agent oxaliplatin has a lower response rate compared to the non-cross resistant agent paclitaxel in cisplatin-resistant ovarian cancer. Alternating therapy with cisplatin and paclitaxel may therefore lead to an improved response rate in ovarian cancer

Alignability and Attribute Importance in Choice

When people choose between two alternatives, like between two colleges, some of the available information is comparable across the alternatives (alignable) and some is noncomparable (nonalignable). For example, when comparing colleges, the academic reputation of both schools may be known (alignable), while the quality of teaching may only be known for one school (nonalignable). Recent research has shown that people use more alignable than nonalignable information in decision making. In this experiment, we consider whether alignable information is preferred even when nonalignable information is important. In the study, some participants rated the importance and valence of a series of statements about colleges that differed in alignability. Other participants made choices between pairs of colleges whose descriptions incorporated these statements. The results indicate that alignable information is preferred to nonalignable information even when the nonalignable information is important. Results also showed that the interpretation of attribute valence depends on alignability. These observations suggest that alignability is more influential than attribute importance in the processing of choice information and that the use of alignable information may facilitate the interpretation of attribute information

The Role of Structural Alignment in Conceptual Combination

Many researchers have suggested that understanding novel noun phrases involves a process of conceptual combination in which people determine how two or more conceptsfittogether to form a new concept. One important way that people combine concepts is by property mapping, which involves asserting that a property of one concq)t is true of the other concept as in, "box that is striped" for "skunk box." A n experiment investigated the hypothesis that property mapping occurs by structural alignment in which mental representations are aligned or put into correspondence. T h e result of this process is primarily a set of matching elements (called commonalities) and a set of mismatching elements related to the commonalities (called alignable differences). The experiment compared property mapping definitions to the alignable differences listed by subjects in a comparison task which is known to involved structural alignment. Consistent with the hypothesis, there was a strong correspondence between property mapping definitions and alignable differences compared to another strategy in conceptual combination not thought to involve structural alignment (slot filling)

How to Resolve an Ethical Dilemma Concerning Randomized Clinical Trials

An apparent ethical dilemma arises when physicians consider enrolling their patients in randomized clinical trials. Suppose that a randomized clinical trial comparing two treatments is in progress, and a physician has an opinion about which treatment is better. The physician has a duty to promote the patient's best medical interests and therefore seems to be obliged to advise the patient to receive the treatment that the physician prefers. This duty creates a barrier to the enrollment of patients in randomized clinical trials.1-10 Two strategies are often used to resolve the dilemma in favor of enrolling patients in clinical trials

Whither structured representation?

The perceptual symbol system view assumes that perceptual representations have a role-argument structure. A role-argument structure is often incorporated into amodal symbol systems in order to explain conceptual functions like abstraction and rule use. The power of perceptual symbol systems to support conceptual functions is likewise rooted in its use of structure. On Barsalou's account, this capacity to use structure (in the form of frames) must be innate.</jats:p