At first, giving baby a dummy becomes a reflex action to facilitate sleep. However, its disadvantages aren't psychological: they're also practical. A dummy can easily become lost, so a baby who drops his dummy in the bed or loses it will inevitably cry for it back.
New mum Laura found baby Josephine was better off without her dummy: "It became a nightmare in just a few weeks! Josephine would wake up as soon as she dropped her dummy. I had to get up, rush through and put it back in her mouth. I'd had enough of it so I taught her to use her thumb instead - at least she knows where to find it!"