  Product search is one of the most popular methods for people to discover and
purchase products on e-commerce websites. Because personal preferences often
have an important influence on the purchase decision of each customer, it is
intuitive that personalization should be beneficial for product search engines.
While synthetic experiments from previous studies show that purchase histories
are useful for identifying the individual intent of each product search
session, the effect of personalization on product search in practice, however,
remains mostly unknown. In this paper, we formulate the problem of personalized
product search and conduct large-scale experiments with search logs sampled
from a commercial e-commerce search engine. Results from our preliminary
analysis show that the potential of personalization depends on query
characteristics, interactions between queries, and user purchase histories.
Based on these observations, we propose a Zero Attention Model for product
search that automatically determines when and how to personalize a user-query
pair via a novel attention mechanism. Empirical results on commercial product
search logs show that the proposed model not only significantly outperforms
state-of-the-art personalized product retrieval models, but also provides
important information on the potential of personalization in each product
search session.
