Here’s my Q&A column from the WSJ this week — and if you have any questions for me, you can tweet them to @danariely with the hashtag #askariely, post a comment on my Ask Ariely Facebook page, or email them to AskAriely@wsj.com.

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Dear Dan,

Why do we ascribe more value to some objects than to others? I’m willing to spend a lot of money on a new high-tech camera but balk at the idea of paying a lot for a new high-tech refrigerator. Why do I react to these possible purchases so differently?

—Hal 

The way we come up with what we are willing to pay for something depends on many factors, including the price we are used to paying, how fair we think it is and how much effort went into the product or service. Another factor is the signaling power of the product: how much it serves to communicate something
about us.

Take cameras. Other people can see us using our amazing new model, and, in return, we can bask in the glory of imagining how these people are admiring our taste and skill. A refrigerator, on the other hand, falls into the category of private consumption. Only guests in our home will ever see the fridge, only a fraction of them will examine it and be impressed, and we usually don’t get (or imagine that we get) extra points from society for that. So we spend much more on products with an element of public consumption to them. This helps to explain the appeal of fancy cars, jewelry and phones too. It’s a very hard force to resist.

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Dear Dan,

One of my co-workers frequently invites me to join him in doing “fun” things outside of work, but I’d rather be with my friends and family, or alone. The activities that he proposes are actually almost always ones I would enjoy. He knows that, so I can’t just say “I don’t like X.” Usually I end up citing scheduling conflicts, but it’s getting harder and harder to make that excuse.

How can I basically say, “I don’t want to spend time with you,” without hurting our professional relationship? Thanks!

—Joe 

I think it’s impossible not to hurt the person at all. But if you want to mitigate the harm, I would use what I call a personal rule. Tell your co-worker that you have a rule about not mixing your personal life with your work life. By casting your refusal to hang out in these terms, you transform your response from a rejection of him as an individual to a rejection of a whole class of social activity. That’s easier to take.

I also think that you might want to reconsider your resistance to socializing in any way with your co-workers. Maybe take February as a month to experiment by agreeing to a few extracurricular outings with people from your office. You might enjoy it.

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Dear Dan,

I am trying to motivate my sister, who is 84, to meet with an estate-planning lawyer. She acknowledges the need, but there’s always an excuse for not proceeding. Nothing is happening. Any suggestions?

—Paul 

Encourage your sister to meet with the lawyer in a restaurant, bar or park (or some other place that she likes) and to bring along a friend whom she likes and trusts. Why? It’s very unpleasant to create an estate plan and to imagine what will happen to your things once you’re dead. Doing this in a pleasant atmosphere, with someone whose company you enjoy, may be enough to counterbalance the unpleasantness. When a positive activity is paired with a dreaded but necessary one, we call this “reward substitution.”

See the original article in the Wall Street Journal here.