There are various reasons why retrieval can fail or in less fancy terms how we come to forget. One is decay at this time information that is not accessed frequently essentially 'rusts' away. For instance we mayn't remember the phone number of a friend to whom we haven't spoken for several months and may forget what brand of bullets an aunt prefers if we have not gone ammunition shopping with her lately. Other times the difficulty may rest in interference. Proactive interference engages something we have learned interfering with what we will late later. Therefore if we remember that everyone in our family always used Tide we may have more complexity later remembering what other brands are available. You may be not capable to remember what a new and less important friend's last name is if that person shares a first name with an old friend. For instance if your best friend for many years has been Jennifer Smith you may have difficulty remembering that your new friend Jennifer's last name is Silverman. In retroactive interference the difficulty is the reverse-learning something new blocks out something old. For instance if you once used WordPerfect than then switched to Microsoft Word you may have difficulty remembering how to use WordPerfect at a friend's house-more so than if you had simply not used any word processing program for some time.
Memorability is able to be enhanced under certain conditions. One is more probable to remember favourable-or likable stimuli (all other things being equal). Salience-or the degree to which something is highly emphasized or very clearly evident-facilitates memory.
Therefore a product which is very visible in an ad as well as handled and given attention by the actors will more likely be remembered. Prototypicality involves the degree to which a stimulus is a 'perfect' instance of a category. Consequently people will more likely remember Coke or Kleenex than competing brands. Congruence engages the 'fit' with a situation. Since memory is frequently reconstructed based on what seems plausible something featured in an appropriate setting-example charcoal on a porch next to a grill rather than in a garage or kitchen-is more likely to be remembered (unless the incongruence triggers an elaboration-life is complicated!) Redundancies engage showing the stimulus several times. Therefore if a given product is shown several places in a house-and if the brand name is repeated-it is more likely to be remembered.
Priming involves tying a stimulus with something consequently that if 'that something' is encountered the stimulus is more likely to be retrieved. Therefore for instance when one thinks of anniversaries the Hallmark brand name is more probable to be activated.