Referencing the object a macro is assigned to

In Excel 2010 how can I reference the object that a macro has been assigned to? I've created a spreadsheet with a form checkbox and assigned this macro to it:

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The checkbox toggles whether or not a picture is visible and that's working fine but I'd like to reuse the script for multiple checkboxes.

The above code is specifically targeting Checkbox1 but I'd like it to target "this", the object I've assigned the macro to.

I feel like this should be really easy but I spent all evening on MSDN, excelforums.com and just googling around but couldn't find the solution.

Thanks in advance!