A generalized sense of number

Much evidence has accumulated to suggest that many animals, including young human infants, possess an abstract sense of approximate quantity, a number sense. Most research has concentrated on apparent numerosity of spatial arrays of dots or other objects, but a truly abstract sense of number should be capable of encoding the numerosity of any set of discrete elements, however displayed and in whatever sensory modality. Here, we use the psychophysical technique of adaptation to study the sense of number for serially presented items. We show that numerosity of both auditory and visual sequences is greatly affected by prior adaptation to slow or rapid sequences of events. The adaptation to visual stimuli was spatially selective (in external, not retinal coordinates), pointing to a sensory rather than cognitive process. However, adaptation generalized across modalities, from auditory to visual and vice versa. Adaptation also generalized across formats: adapting to sequential streams of flashes affected the perceived numerosity of spatial arrays. All these results point to a perceptual system that transcends vision and audition to encode an abstract sense of number in space and in time.     

Impact of high mathematics education on the number sense

In adult number processing two mechanisms are commonly used: approximate estimation of quantity and exact calculation. While the former relies on the approximate number sense (ANS) which we share with animals and preverbal infants, the latter has been proposed to rely on an exact number system (ENS) which develops later in life following the acquisition of symbolic number knowledge. The current study investigated the influence of high level math education on the ANS and the ENS. Our results showed that the precision of non-symbolic quantity representation was not significantly altered by high level math education. However, performance in a symbolic number comparison task as well as the ability to map accurately between symbolic and non-symbolic quantities was significantly better the higher mathematics achievement. Our findings suggest that high level math education in adults shows little influence on their ANS, but it seems to be associated with a better anchored ENS and better mapping abilities between ENS and ANS.     

Texture density adaptation and visual number revisited

Burr and Ross [1] have recently proposed that the visual dimension of number is itself directly adaptable. The aftereffect they describe is one that my colleagues and I previously used to investigate the perception of texture density [2-4]. Burr and Ross [1] argue that the effect is new because it concerns visual number, rather than texture density, but they did not report critical tests to support this claim. Here, I shall briefly describe the striking similarity between our prior work and that of Burr and Ross [1], and discuss how some of our results rule out Burr and Ross's [1] interpretation that numerosity, and not density, is at play. I shall also provide a new demonstration that confirms that these effects are based on density, using a display that explicitly dissociates density from numerosity. Taken together, this line of arguments suggests that Burr and Ross's [1] recent study may best be thought of as replicating support within a well-established line of work on texture density.     

A sense of history

Mating preferences for specific traits increase the fertility, fecundity or offspring fitness of choosy individuals. However, current fitness benefits offer an incomplete account of the relative influence of different signals on mate choice. The history of selection on sensory systems in a broader ecological context can provide many missing details. Recent innovative use of neural networks by Phelps and Ryan shows that modelling the chronological order in which past selective forces have acted predicts the actual mating preferences of túngara frogs.     

A false sense of security

Some journals are using ineffective software to screen images for manipulation. In doing so, they are creating a false sense of security in the research community about the integrity of the image data they publish.“There must be an easier way!” It''s the mantra of anyone performing a labor-intensive task, and the motivation behind the human desire for automation. Apparently, it also holds true for image screening.Open in a separate windowFigure 1©cartoonbank.com. All Rights Reserved.At the Rockefeller University Press, we screen all images in all accepted papers for evidence of manipulation (1). We do this by visually inspecting every image using basic adjustments in Photoshop. When editors from other publishers see a demonstration of our process, they often assert, “There must be an easier way!”The possibility of automating the image screening process was described in a Nature news article more than two years ago (2). About a year ago, one of the largest publisher services providers, Cadmus Communications, started offering an automated image screening service using a program called Rigour, which they publicize as “the world''s first automated Image Manipulation Analysis Software” (www.suprocktech.com).Cadmus demonstrated an early version of this software at the Press, but we found that it could not detect blatant examples of band deletions, band intensity adjustments, large regions of duplication, or composite images. In an e-mail to Cadmus dated September 11, 2007, I expressed my concern, “I am worried about causing a setback in the publishing community if editors think the current Rigour software is effective at detecting problems in biomedical images (specifically gel images). I have already heard of editors saying they will not initiate visual screening because they will just use the Cadmus software. This is creating a false sense of security in the community, because the software is not yet an effective screening tool.” I received no response to this e-mail.I was surprised to learn that, within a couple of months, Cadmus had started to sell an image screening service to publishers using this software. But given the availability of such a service, I was not surprised to learn that editors at two very prominent journals were using it. Publishers were clearly looking for a less labor-intensive solution to an image problem, in two senses of the word—image data, and public image. They wanted to be seen by the public to be actively addressing the problem of image manipulation.I asked these publishers if they had tested the service before they started to use it. Both had done so, but one of them declined to send the results of their tests; the other indicated that the Cadmus service had a 20% success rate. It seems that these publishers were not really concerned if the screening process they used actually worked.Problems with the service were still evident recently when I was consulted by a third party about a case of image manipulation in a paper published in one of these journals. The paper made a surprising claim with important clinical implications. Given that journal''s policy of only screening a fraction of papers for image manipulation, one might expect that they would at least select those with important clinical implications. In fact, the papers are selected at random, and this one had not been screened. After questions were raised, the figures were screened by Cadmus using their software, but they did not detect problems with the images that were easily revealed with visual screening.In personal communications, publishers have argued that using the Cadmus service must be better than doing nothing. In fact, it is worse than doing nothing. These publishers are creating a false sense of security in the community about the integrity of the image data they publish.A recent test of the Cadmus image screening service showed some improvement, with the software detecting manipulation in 10 out of 22 images (45%) in which image manipulation had previously been detected by visual inspection. However, when multiplied by the small fraction of images being screened by these journals, the percentage of images that are effectively screened is dramatically lower. At the very least, these journals should fully disclose their screening practices (and their efficacy) to their readers.Although complete protection against manipulated images cannot be guaranteed, it is incumbent on journal editors to screen the images they publish using the best available method, not just to some known (and low) percentage of efficacy. The issue of data integrity should not be left to chance and probability. This is scholarly publishing, not blackjack.There are others developing software to detect image manipulation, and it is possible that these applications may eventually prove to be useful and effective tools for editors. But journal editors should not rely on an automated method for image screening unless they know it is as effective as the visual method. Otherwise, readers are left to hedge their bets.     

A cellular sense of touch

How cells sense and respond to physical forces is an area of intense investigation, which poses significant challenges for in vitro experiments and even greater obstacles for in vivo studies. Analyses of integrin complex dynamics in Drosophila melanogaster now provide evidence that altering mechanical force modulates the stability of integrin adhesion in vivo.     

United we sense, divided we fail: context-driven perception of ambiguous visual stimuli

Ambiguous visual stimuli provide the brain with sensory information that contains conflicting evidence for multiple mutually exclusive interpretations. Two distinct aspects of the phenomenological experience associated with viewing ambiguous visual stimuli are the apparent stability of perception whenever one perceptual interpretation is dominant, and the instability of perception that causes perceptual dominance to alternate between perceptual interpretations upon extended viewing. This review summarizes several ways in which contextual information can help the brain resolve visual ambiguities and construct temporarily stable perceptual experiences. Temporal context through prior stimulation or internal brain states brought about by feedback from higher cortical processing levels may alter the response characteristics of specific neurons involved in rivalry resolution. Furthermore, spatial or crossmodal context may strengthen the neuronal representation of one of the possible perceptual interpretations and consequently bias the rivalry process towards it. We suggest that contextual influences on perceptual choices with ambiguous visual stimuli can be highly informative about the neuronal mechanisms of context-driven inference in the general processes of perceptual decision-making.     

A sense of danger from radiation

Tissue damage caused by exposure to pathogens, chemicals and physical agents such as ionizing radiation triggers production of generic "danger" signals that mobilize the innate and acquired immune system to deal with the intrusion and effect tissue repair with the goal of maintaining the integrity of the tissue and the body. Ionizing radiation appears to do the same, but less is known about the role of "danger" signals in tissue responses to this agent. This review deals with the nature of putative "danger" signals that may be generated by exposure to ionizing radiation and their significance. There are a number of potential consequences of "danger" signaling in response to radiation exposure. "Danger" signals could mediate the pathogenesis of, or recovery from, radiation damage. They could alter intrinsic cellular radiosensitivity or initiate radioadaptive responses to subsequent exposure. They may spread outside the locally damaged site and mediate bystander or "out-of-field" radiation effects. Finally, an important aspect of classical "danger" signals is that they link initial nonspecific immune responses in a pathological site to the development of specific adaptive immunity. Interestingly, in the case of radiation, there is little evidence that "danger" signals efficiently translate radiation-induced tumor cell death into the generation of tumor-specific immunity or normal tissue damage into autoimmunity. The suggestion is that radiation-induced "danger" signals may be inadequate in this respect or that radiation interferes with the generation of specific immunity. There are many issues that need to be resolved regarding "danger" signaling after exposure to ionizing radiation. Evidence of their importance is, in some areas, scant, but the issues are worthy of consideration, if for no other reason than that manipulation of these pathways has the potential to improve the therapeutic benefit of radiation therapy. This article focuses on how normal tissues and tumors sense and respond to danger from ionizing radiation, on the nature of the signals that are sent, and on the impact on the eventual consequences of exposure.     

The distribution and number of the skin sense organs of agamid, iguanid and gekkonid lizards

The topography and numerical distribution of the skin receptors in 29 lizard species including 18 agamids, eight iguanids and three gekkonids, are compared and contrasted. There are no marked differences in the number of receptors in the dorsal and ventral surfaces of the body in the different groups. The maximal density of the receptors occurs on the head and decreases in the caudal direction.
Iguanids and gekkonids have 5–6 times more receptors than agamids. Agamids Gonocephalus grandis from S.E. Asia, Pogona barbata, Diporiphora bilineata from Australia and Ceratophora tennentii from Sri-Lanka, however, are distinguished by their high density of receptors, especially on the head. Species of Physignathus are similar to iguanids in this way. The agamid Phrynocephalus mystaceus shows considerable differences, in receptor number, from other species of this genus. There is a high density of receptors on the caudal scales of the Madagascan iguanid Oplurus , and a similar high density of receptors on the ventral surface of the gecko Teratoscincus scincus.