Fixed vs. variable noise in 2AFC contrast discrimination: lessons from psychometric functions.

Recent discussion regarding whether the noise that limits 2AFC discrimination performance is fixed or variable has focused either on describing experimental methods that presumably dissociate the effects of response mean and variance or on reanalyzing a published data set with the aim of determining how to solve the question through goodness-of-fit statistics. This paper illustrates that the question cannot be solved by fitting models to data and assessing goodness-of-fit because data on detection and discrimination performance can be indistinguishably fitted by models that assume either type of noise when each is coupled with a convenient form for the transducer function. Thus, success or failure at fitting a transducer model merely illustrates the capability (or lack thereof) of some particular combination of transducer function and variance function to account for the data, but it cannot disclose the nature of the noise. We also comment on some of the issues that have been raised in recent exchange on the topic, namely, the existence of additional constraints for the models, the presence of asymmetric asymptotes, the likelihood of history-dependent noise, and the potential of certain experimental methods to dissociate the effects of response mean and variance.

The challenges of safeguarding and securing cultural heritage materials during violent conflict in Nigeria.

Almost every community, country and continent is experiencing a form of conflict, war or disaster. These wars have claimed lives, antiquities, heritage materials, contemporary Arts, Galleries, Museums, Archives, Monuments andHeritage sites. The aim of this study is to explore the challenges of safeguarding cultural heritage material during violent conflict in Nigeria bearing in mind the two UNESCO world heritage sites in Nigeria: Sukur kingdom and Osun Oshogbo sacred Grove. The outcome of this study will help the policy makers to address the challenges of safeguarding cultural heritage materials in times of conflicts, bridge the gap on the existing literature concerning the safeguarding of cultural heritage materials in times of conflict and to make a modest contribution to the existing body of knowledge on cultural heritage protection in Nigeria in particular and other parts of the world in general. This study relies on both primary and secondary sources using questionnaire and oral interview to elicit information from selected relevant cultural agencies, journalists and scholars in the field of art and culture. Relevant literature and documents on the challenges of safeguarding and securing of cultural heritage materials during conflicts were reviewed. The data gathered from the questionnaires and the oral interview is presented in frequency tabular form to give precise and comprehensive insight into the study findings. Notable among the challenges were insecurity and lack of professionalism in the field of cultural heritage profession. The study also revealed that governments are not enforcing the global laws and conventions for the protection of cultural heritage materials in times of violent conflict. The communities where these materials are located have little or no knowledge about the import of these materials and do not take part in securing them in the event of conflict. It is crucial that we place high value on heritage materials since they are inextricably linked with our identity and where we come from. It is strongly recommended that Cultural Heritage Institutions should involve as much as possible the local communities living around the sites by creating awareness educating and encouraging them to take ownership of the Sites located within their communities. They must ensure that the site is safeguarded against all forms of threat. Items of heritage value are not often considered in most disaster management plans therefore there is the need to consider heritage as priority just as the protection of lives and property.