  Recent research advances in Computer Vision and Natural Language Processing
have introduced novel tasks that are paving the way for solving AI-complete
problems. One of those tasks is called Visual Question Answering (VQA). A VQA
system must take an image and a free-form, open-ended natural language question
about the image, and produce a natural language answer as the output. Such a
task has drawn great attention from the scientific community, which generated a
plethora of approaches that aim to improve the VQA predictive accuracy. Most of
them comprise three major components: (i) independent representation learning
of images and questions; (ii) feature fusion so the model can use information
from both sources to answer visual questions; and (iii) the generation of the
correct answer in natural language. With so many approaches being recently
introduced, it became unclear the real contribution of each component for the
ultimate performance of the model. The main goal of this paper is to provide a
comprehensive analysis regarding the impact of each component in VQA models.
Our extensive set of experiments cover both visual and textual elements, as
well as the combination of these representations in form of fusion and
attention mechanisms. Our major contribution is to identify core components for
training VQA models so as to maximize their predictive performance.
