產品線延伸一直是企業追求成長、導入新產品的主要途徑。然而，新產品往往影響到消費者對產品線中既有產品的評價，反之亦然，亦即產生所謂的外溢效果。現有文獻顯示，產品線的外溢效果絕大部分取決於產品本身的特性，因此留給行銷實務工作者很少的發揮空間。然而，本研究認為，藉由使用不同的廣告策略，行銷人員能夠將負面的產品線外溢效果轉變為正面的效果。透過三項實驗，本研究發現廣告策略類型與產品線類型間存在交互作用，且交互作用的強度受到品牌聯想類型與屬性呈現方式所影響。本研究發現，對垂直產品線中的高端產品與水平產品線中某特定產品而言，採用品牌型廣告能提高消費者對同一產品線中另一項產品的評價；但對於垂直低端產品而言，前述效果則發生在採用資訊型廣告時。此外，研究結果進一步顯示，無論對垂直或水平產品線，品牌型廣告的外溢效果在採用中心性品牌聯想實比周邊性聯想時強烈；而資訊型廣告的外溢效果則是在產品屬性以數字呈現時以文字呈現時更加顯著。

Line extensions have being important ways for growth and new product introductions in many companies. However, the presence of the new product affects consumer evaluations of the existing products in the same product line, and vice versa, generating the so-called spillover effects. Extant literature reveals that the product line spillovers are determined by the features of product itself leaving little room for marketing practice. However, this research argues that marketers can use different advertising strategies turn a negative spillover effect into a beneficial one. Through three experiments, this research reveals the interaction between advertising strategies and product line types. The author found that for the high-end product in a vertical line (as well as one certain product in a horizontal line), brand advertising increases consumers valuations of another product in the same line; however, for a vertical low-end product, the foregoing effect occurs when informational advertising is used. This research further shows that, for all types of product line, central associations in brand advertising evoke larger valuation changes than peripheral associations, and numerical presentation in informational advertising leads to larger valuation changes than literal presentation.