13 research outputs found
Are Accuracy and Robustness Correlated?
Machine learning models are vulnerable to adversarial examples formed by
applying small carefully chosen perturbations to inputs that cause unexpected
classification errors. In this paper, we perform experiments on various
adversarial example generation approaches with multiple deep convolutional
neural networks including Residual Networks, the best performing models on
ImageNet Large-Scale Visual Recognition Challenge 2015. We compare the
adversarial example generation techniques with respect to the quality of the
produced images, and measure the robustness of the tested machine learning
models to adversarial examples. Finally, we conduct large-scale experiments on
cross-model adversarial portability. We find that adversarial examples are
mostly transferable across similar network topologies, and we demonstrate that
better machine learning models are less vulnerable to adversarial examples.Comment: Accepted for publication at ICMLA 201
Adversarial Robustness: Softmax versus Openmax
Deep neural networks (DNNs) provide state-of-the-art results on various tasks
and are widely used in real world applications. However, it was discovered that
machine learning models, including the best performing DNNs, suffer from a
fundamental problem: they can unexpectedly and confidently misclassify examples
formed by slightly perturbing otherwise correctly recognized inputs. Various
approaches have been developed for efficiently generating these so-called
adversarial examples, but those mostly rely on ascending the gradient of loss.
In this paper, we introduce the novel logits optimized targeting system (LOTS)
to directly manipulate deep features captured at the penultimate layer. Using
LOTS, we analyze and compare the adversarial robustness of DNNs using the
traditional Softmax layer with Openmax, which was designed to provide open set
recognition by defining classes derived from deep representations, and is
claimed to be more robust to adversarial perturbations. We demonstrate that
Openmax provides less vulnerable systems than Softmax to traditional attacks,
however, we show that it can be equally susceptible to more sophisticated
adversarial generation techniques that directly work on deep representations.Comment: Accepted to British Machine Vision Conference (BMVC) 201
Adversarial Diversity and Hard Positive Generation
State-of-the-art deep neural networks suffer from a fundamental problem -
they misclassify adversarial examples formed by applying small perturbations to
inputs. In this paper, we present a new psychometric perceptual adversarial
similarity score (PASS) measure for quantifying adversarial images, introduce
the notion of hard positive generation, and use a diverse set of adversarial
perturbations - not just the closest ones - for data augmentation. We introduce
a novel hot/cold approach for adversarial example generation, which provides
multiple possible adversarial perturbations for every single image. The
perturbations generated by our novel approach often correspond to semantically
meaningful image structures, and allow greater flexibility to scale
perturbation-amplitudes, which yields an increased diversity of adversarial
images. We present adversarial images on several network topologies and
datasets, including LeNet on the MNIST dataset, and GoogLeNet and ResidualNet
on the ImageNet dataset. Finally, we demonstrate on LeNet and GoogLeNet that
fine-tuning with a diverse set of hard positives improves the robustness of
these networks compared to training with prior methods of generating
adversarial images.Comment: Accepted to CVPR 2016 DeepVision Worksho
How possible is the development of an operational psychometric method to assess the presence of the 5-HTTLPR s allele? Equivocal preliminary findings
<p>Abstract</p> <p>Objective</p> <p>The s allele of the 5-hydroxytryptamine transporter-linked promoter region (5-HTTLPR) polymorphism of the serotonin transporter gene has been found to be associated with neuroticism-related traits, affective temperaments and response to selective serotonin reuptake inhibitor (SSRI) treatment. The aim of the current study was to develop a psychometric tool that could at least partially substitute for laboratory testing and could predict the presence of the s allele.</p> <p>Methods</p> <p>The study included 138 women of Caucasian origin, mean 32.20 ± 1.02 years old. All subjects completed the Hungarian standardised version of the Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego Autoquestionnaire (TEMPS-A) instrument and were genotyped for 5-HTTLPR using PCR. The statistical analysis included the calculation of the Index of Discrimination (D), Discriminant Function Analysis, creation of scales on the basis of the above and then item analysis and calculation of sensitivity and specificity.</p> <p>Results</p> <p>Four indices were eventually developed, but their psychometric properties were relatively poor and their joint application did not improve the outcome.</p> <p>Conclusions</p> <p>We could not create a scale that predicts the 5-HTTLPR genotype with sufficient sensitivity and specificity, therefore we could not substitute a psychometric scale for laboratory genetic testing in predicting genotype, and also possibly affective disorder characterisation and treatment.</p