• Hal Pashler, whose criticisms of interpretations of brain scans we reported (2 May, p 4), is at the University of California, San Diego.
• We got the time it takes light to arrive from the Horsehead nebula wrong by a factor of a million: the light we see from it is a mere 1500 years old (9 May, p 46).
• TCP/IP is a set of communications protocols, not a language (2 May, p 28); we should have recognised the clue in the two Ps.
